#1/4 wavelength gp antenna

[eteily4]

Exploring the Different Types of RF Antennas

Radio Frequency (RF) antennas are crucial components in a wide range of communication systems, including cellular networks, satellite communications, Wi-Fi, and Bluetooth technologies. Their major job is to transform electrical signals into electromagnetic waves, which they then transmit and receive. The design, selection, and implementation of the appropriate antenna type has a significant impact on communication system performance, range, and efficiency. In this article, we will look at the many types of RF antennas, their properties, applications, and when to utilize each one.

1. Dipole antennas

The dipole antenna is one of the simplest and most used types of antenna. It consists of two conducting pieces, usually made of metal, aligned in a straight line with a feed point in the middle. The dipole antenna functions at its resonant frequency when its entire length is roughly half the wavelength of the signal.

Characteristics:

Simple design

Ideal for sending and receiving omnidirectional signals in the horizontal plane.

Effective for frequencies from 30 MHz to 300 MHz (HF to UHF bands)

Applications:

Used for radio transmission and reception.

Frequently used in television and radio transmission.

simple communication systems, such as walkie-talkies.

2. Monopole antennas

A monopole antenna is similar to a dipole, except it has a single conducting element positioned above the ground plane. This ground plane functions as a reflector, which improves the antenna's effectiveness. The monopole antenna is essentially a half-dipole antenna with a ground plane to complete the circuit.

Characteristics:

Needs a ground plane or reflective surface.

Compact and easily integrated into mobile devices.

Typically performs well in vertical polarization patterns.

Applications:

Cell phones and other mobile devices

utilized in radio and television transmission systems.

Found in GPS and other communication devices.

3. Yagi-Uda antennas

The Yagi-Uda antenna is a highly directional antenna made up of several elements, including a driving element, a reflector, and one or more directors. The driven element is often a dipole, whereas the reflector and directors are passive components that help focus the signal in a specific direction.

Characteristics:

Highly directional and provides significant gain in a particular direction.

Precise alignment is required for best performance.

Can be constructed for a broad variety of frequencies.

Applications:

Used for television reception.

Satellite communications systems

Radar and wireless communication applications.

4. Parabolic antennas

Parabolic antennas, also known as parabolic dishes, have a curved shape that directs receiving signals to a single focal point, where the receiver or transmitter is positioned. This form enables for great directivity and gain.

Characteristics:

Very high gain and great directivity.

Frequently used in satellite communication and radar systems.

Large and hefty, they are appropriate for fixed installations.

Applications:

Used for satellite communication, such as dish antennas.

Radar systems are used for weather monitoring and military purposes.

Long-range point-to-point wireless transmission.

5. Patch antennas

Patch antennas, also known as microstrip antennas, are flat, small antennas made up of a conducting patch mounted on top of a dielectric substrate. These antennas are normally square, rectangular, or circular, and can be tailored to certain frequencies.

Characteristics:

Small, lightweight, and easily integrated into gadgets.

Low profile makes them excellent for tiny devices.

Can be designed for a broad range of frequencies and polarizations.

Applications:

GPS receivers and smartphones

Used in wireless communication systems, such as Wi-Fi and Bluetooth.

Frequently utilized in aircraft and military systems for radar and communication.

6. Helical antennas

Helical antennas feature a spiral-shaped conductor twisted around a central axis. These antennas can operate in both axial and normal modes, with the axial mode producing a more directed radiation pattern.

Characteristics:

Compact, has a broad bandwidth.

It produces circular polarization, which is suitable for satellite communications.

Depending on the design, radiation patterns might be omnidirectional or directed.

Applications:

Satellite Communication

Space Exploration and Communication

Used in some GPS and mobile communications.

7. Log-periodic Antennas A log-periodic antenna is made up of several elements of varied lengths set in a periodic pattern along a central boom. This design enables the antenna to function over a wide variety of frequencies without having to be retuned.

Characteristics:

Wide bandwidth and multi-frequency operation.

Directional antennas provide strong gain in a single direction.

Can be pretty huge depending on frequency coverage.

Applications:

Broadcasting and receiving various TV and radio broadcasts.

Used in radio frequency measurement and testing equipment.

Found in R&D, including antenna testing setups.

8. Slot antennas

Slot antennas are a form of aperture antenna in which a slot or gap is carved into a conducting surface. These antennas are often installed on a metal plate or within a waveguide construction and are distinguished by their unique qualities, such as wide bandwidth and low profile.

Characteristics:

Compact design with good performance.

Wide bandwidth and low radiation resistance.

Suitable for both circular and linear polarization.

Applications:

Frequently used in radar and communication systems.

Common in military and aviation applications.

Used in specific microwave systems.

9. Aperture antennas

Aperture antennas, such as horn antennas, use an aperture (a hole or opening) in a conductor to emit electromagnetic waves. These antennas are commonly employed in higher frequency ranges.

Characteristics:

Provide a highly directional beam of radiation.

High efficiency and very simple construction

Generally larger and utilized in specialist applications.

Applications:

High-frequency communication systems.

Radar and satellite communication

Used for RF testing and some scientific purposes.

Conclusion

A variety of criteria influence the selection of an RF antenna, including frequency range, desired gain, polarization, and application. While certain antennas, such as the dipole and monopole, are basic and ideal for general communication systems, others, such as the parabolic and Yagi-Uda antennas, provide high gain and directivity for more specialized applications. Understanding the properties of each antenna type enables engineers to choose the best one for a given application, hence improving performance, efficiency, and cost. Whether for long-range satellite communications or short-range wireless systems, the RF antenna is still an essential component of current communication networks.

[spacenutspod]

4 min read Ride the Wave of Radio Astronomy During the Solar Eclipse   GAVRT DSS-28 dish at the NASA Deep Space Communications Complex near Goldstone, California. NASA/Russell Torres Students and science enthusiasts are invited to catch a real-time look at radio astronomy as scientists explore magnetic hotspots on the Sun during a live, virtual solar eclipse event on April 8, 2024. A massive, 34-meter telescope once used by NASA’s Deep Space Network to communicate with spacecraft will point towards the Sun during the solar eclipse that day. The Moon’s position in front of the Sun will help the antenna detect radio waves from solar active regions in more detail than is usually possible.  The Solar Patrol team at California’s Lewis Center for Educational Research, in partnership with NASA’s Jet Propulsion Laboratory, will remotely operate the Goldstone Apple Valley Radio Telescope (GAVRT) while sharing observations and commentary during an interactive webinar open for the public.  Scientists and students regularly use the single-dish GAVRT antenna, located in the Mojave Desert of California, to scan the Sun. They use the observations to build maps of radio waves formed along strong magnetic field lines in the outer atmosphere of the Sun. By studying these images, researchers can measure the strength and structure of those powerful magnetic regions. These observations offer insight into magnetically driven processes on the Sun, like solar flares and coronal mass ejections, which generate space weather events that can interfere with satellite electronics, radio communications and GPS signals, spacecraft orbits, and power grids on Earth.  During normal solar observing, GAVRT can only detect and distinguish relatively large features on the Sun. A solar eclipse offers a unique opportunity for GAVRT to capture sharper and more refined information about the magnetic field structure in the solar active regions that are often marked by sunspots. “It’s special during the eclipse because, as the Moon is passing in front of an active region, that really sharp edge of the Moon covers up more and more of the structure in that active region,” says Marin Anderson, a research scientist at NASA’s Jet Propulsion Laboratory and GAVRT Solar Patrol scientist.  Anderson explains how, as the Moon blocks a portion of the active region, it’s easier to tell what part of the active region the radio emissions are coming from.  “It’s basically a way of probing magnetic field structures in the corona of the Sun in a way that we wouldn’t be able to unless an eclipse was happening.”  Anyone in the world can join the live-streamed webinar on April 8 from 1-3:30 p.m. EDT (10 a.m. to 12:30 p.m. PDT) and ask the hosts questions as a partial eclipse becomes visible in California. Participants will be able to see the telescope controls, data visualization tools like Helioviewer, incoming radio data, a map of active hot spot regions, and imagery of the eclipsed Sun at radio wavelengths.  Eclipse maximum, as observed by GAVRT in radio waves at 6.00 GHz and 8.45 GHz, on October 14, 2023. Click the arrow to see the post-eclipse Sun. NASA/Thangasamy Velusamy Post-eclipse image of the Sun, as observed by GAVRT at 6.00 GHz and 8.45 GHz, on October 14, 2023. One of the active regions monitored by GAVRT during the eclipse is visible as the bright region in the lower left quadrant of the Sun. Click the arrow to see the eclipsed Sun. NASA/Thangasamy Velusamy GAVRT was awarded a NASA grant to carry out observations during both the 2023 and 2024 solar eclipses in the U.S. GAVRT supports an open science framework by making all data and radio maps available for viewing and downloading by the public. Images collected during the eclipse will be posted online with instructions on how to run software and analyze the data.  The Solar Patrol team hopes the public webinar inspires people to become active members of the GAVRT program where they can learn to remotely operate the telescope themselves while taking part in data analysis and scientific discovery.  “I think one of the really great aspects of GAVRT Solar Patrol is that it connects any participant, but particularly students, with the Sun, beyond what they see and experience every day from the star,” Anderson says. “It’s seeing the Sun at radio wavelengths and being able to connect different parts of the electromagnetic spectrum with unique physics that’s happening on the Sun.” Since its launch in 1997, GAVRT has offered many opportunities to combine science observations with education and outreach. In addition to Solar Patrol, GAVRT is used in campaigns where participants can study Jupiter’s radiation belts, monitor radio emissions from black holes, or search for extraterrestrial intelligence. Anderson says giving students the tools to do science themselves empowers them.  “It’s a really hands-on process and I think the way to get kids excited and invested in not only solar science but the scientific process in general.”  To register for the GAVRT April 8 eclipse livestream event, visit: https://register.gotowebinar.com/register/4920123655757293655 For other ways to get involved in GAVRT, including signing up a classroom to participate in observations, contact: mc@lcer.org or visit gavrt.lewiscenter.org. By Rose Brunning, Communications LeadNASA Heliophysics Digital Resource Library Share Details Last Updated Feb 21, 2024 Related Terms 2024 Solar Eclipse Eclipses Skywatching Solar Eclipses Keep Exploring Discover More on the 2024 Solar Eclipse Shadow Notes Eclipse 2024 Science Eclipse 2024 Citizen Science Safety

[ct-rfantennas]

C&T RF Antennas Inc - Outdoor N-type fiberglass outdoor waterproof Antenna with RG58 cable extension pigtail

[xiaoquebanxiaoqueban]

4G smart phone antenna is so bad you know

1、 At present, various mobile phone manufacturers are generally troubled by

recently, when communicating with mobile phone resources and R & D personnel of various brands, a common problem bothering us is: in the rapid development of 4G era, antenna has become a bottleneck of current handheld terminals. At present, no matter Shuo Beide and Xinwei, which have a large share in the domestic mobile phone antenna market, or some representatives of the old antenna manufacturers transforming to mobile terminals, such as taimeng (Taiwan), are facing the huge challenges brought by 4 G antennas. Let's explore what causes this technical problem.

2、 The tasks and challenges facing antennas

mobile data users around the world want their devices to be connected at high speed anywhere in the world. This expectation brings huge burden to network and equipment performance. In mobile data devices, the antenna is the only part of the "contact" network, so it is more and more important to optimize the antenna performance. However, the design of 4G antenna in smart phones and tablet computers is facing great challenges.

In China, we often say five modes and ten frequencies. It means that different operators use different standards and use different wireless frequency bands. In addition, there are Bluetooth, WiFi, radio, GPS and so on. Any contact with the outside world is inseparable from the antenna. But now in building antennas components                     the mobile phone flat panel is developing in the direction of light and thin, which gives the antenna less and less space.

Today, let's look at how antennas accomplish this task and challenge in the 4G era.

We know that there are many factors that affect the antenna performance of handheld mobile communication devices. Although these reasonsElements are related, but they can be divided into three categories: antenna size, mutual coupling between multiple antennas, and equipment usage model.

Antenna size depends on three elements

antenna size depends on three elements: working bandwidth, operating frequency and radiation efficiency. Today, the demand for bandwidth is higher and higher, which is driven by the FCC frequency allocation in the United States and the roaming protocol of operators all over the world; different regions use different frequency bands. "Bandwidth is directly related to antenna size" and "efficiency is directly related to antenna size" - which usually means that larger antennas can provide greater bandwidth and higher efficiency.

In addition to the bandwidth, the antenna size also depends on the operating frequency. In North America, carrier Verizon Wireless and at & T mobility choose to promote LTE, which is the abbreviation of long term evolution. LTE, also known as 3.9G, has 100Mbps data download capability, and is regarded as the mainstream technology evolving from 3G to 4G. '

the product operates in the 700MHz band, which was part of the FCC uhf-tv reallocation band a few years ago. These new bands (17704-746mhz and 13746-786mhz) are lower than the traditional cellular band (5824-894mhz) used in North America. This change is huge, because the lower the frequency, the longer the wavelength, so a longer antenna is needed to keep the radiation efficiency constant. In order to ensure the radiation effectThe antenna size must be large. However, the device system designers also need to add larger displays and more functions, so the available antenna length and overall volume are greatly limited, which reduces the antenna bandwidth and efficiency.

Interference prevention is needed for mutual coupling between antennas

the high-speed wireless protocol with mutual coupling update between antennas requires the use of MIMO (multiple input multiple output) antennas. MIMO requires multiple antennas (usually two) working at the same frequency at the same time. Therefore, multiple antennas need to be placed on the phone equipment, and these antennas should work at the same time and have no influence on each other. When two or more antennas are close together, a phenomenon called mutual coupling occurs.

For example, two antennas are placed next to each other on the mobile platform. Part of the energy radiated from antenna 1 will be intercepted by antenna 2. The intercepted energy will be lost in the terminal of antenna 2 and can not be utilized. This can be expressed by the loss of system power added efficiency (PAE). According to the principle of interchangeability, this effect is the same in both transmit and receive modes. The coupling amplitude is inversely proportional to the separation distance of the antenna. For mobile phone implementation, the distance between antennas working in the same frequency band in MIMO and diversity applications can be 1 / 10 wavelength or less. For example, the free space wavelength at 750MHz is 400mm. When the interval is very small, such as far less than one wavelength, the coupling will be very high. The energy coupling between antennas is useless and only reduces data throughput and battery life.

Device usage model affects antenna

compared with the traditional mobile phone, the device usage model affects the antenna,The use model of smartphones and tablets has changed a lot. In addition to normal operation, these devices also meet the requirements of electromagnetic wave energy absorption ratio (SAR) and hearing aid compatibility (HAC) regulations.

Another aspect of the usage model is the type of content consumed. Video intensive mobile applications such as massively multiplayer online role-playing games (MMORPG) and real-time video data streams continue to drive data usage soaring. According to the CAG growth rate of 42% in 2009 for Western Europe and 42% for North America, respectively. These similar applications are driving manufacturers to produce larger, higher resolution displays. The increase of data utilization rate is also quietly changing the way consumers hold these devices. For example, for a game application, the user must hold both ends of the device with both hands, while other applications may not need to hold the device at all.

With the increase of the display screen and the change of the user's grasp mode, it is more and more difficult to find a good position for the antenna radiation unit which is not blocked by the display screen or the user's palm. In addition to these constraints, equipment manufacturers want product lines to have fewer SKUs, and developing platforms that can work anywhere in the world is the trend for such products.

In addition, some terminals use metal shell, which will also bring great challenges to the antenna signal reception.

To sum up the reasons of these aspects, this paper gives the design of mobile 4G antennaThe design and manufacture brings great challenge. How to design and manufacture smaller and stronger antennas in limited space. This requires the industry's unremitting investment. How to find balance in contradiction? We will discuss the corresponding solutions in the future.

3、 At present, the distribution of domestic wireless frequency band:

the following is the distribution table of each wireless frequency band in China:

description of domestic wireless spectrum allocation:

domestic wireless spectrum analysis (WRC-07 new allocated frequency band analysis):

about 4G antenna, more exciting, to be continued 。

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WFT is Bluetooth?

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Bluetooth is a wireless technology standard used for exchanging data between fixed and mobile devices over short distances using short-wavelength UHF radio waves. (Wikipedia) This post may contain affiliate links, please read my disclosure here Bluetooth was created to replace wired connections and enable wireless communications. Compared to other wireless connection it has a relatively low power consumption. Bluetooth is managed by the Bluetooth Special Interest Group (SIG), which has more than 35,000 member companies in the areas of telecommunication, computing, networking, and consumer electronics. (Wikipedia) The range for Bluetooth varies depending on surrounding conditions, materials around, production variations of the devices, antenna configurations, and battery conditions. Most Bluetooth applications are for indoor conditions, as there are fewer objects and situations that could cause loss of the connection.

Five Things You Don't Know About Bluetooth Range from Bluetooth SIG on Vimeo. The connection between Bluetooth and other devices typically operates in 1:1 pairings, where the connection is dependent on the device. So your Bluetooth headphones are dependant on your phone when you connect them and they do whatever your phone says. Currently, Bluetooth devices support up to two streams of music to different products. Bluetooth versions The latest series of Bluetooth is 5. The latest version is 5.2 which brings a few changes to the capabilities for the technology. Bluetooth 4.0 vs. Bluetooth 5.0 https://ift.tt/2CpX1tv The major difference between various iterations is the range, battery life, and compatibility. These are all important when choosing your Bluetooth headphones. Here are some of the biggest differences between Bluetooth 4.0 and the new and improved Bluetooth 5.0: Bluetooth 4 was developed to manage “the internet of things.” It is a bit older tech based on the life and speed of technological changes. Bluetooth 4.1 features include: » 24 MBps speeds » 300-foot coverage » 2.4 to 2.485 GHz bandwidths This version was one of the first to be more stable and be able to work with most devices. Bluetooth 4 and its sub iterations introduced the ability to use low energy or low power Bluetooth for longer battery life. Bluetooth 5.0 came out in 2016 with some upgrades that included a significant improvement in speed to 48 MBps, an extended range that measured at 985 feet, and advancements in privacy and security for the system. These changes were a great boost to the development of Bluetooth speakers. The triple increase of the range allows you to play music from your phone or computer to speakers that are across the room and then some. One thing to note is that Bluetooth 5.0 devices are not all backward compatible with older devices. So make sure that your phone and other devices can handle your brand new gadget with this latest version. While you would not need an extended range or faster speed necessary for your headphones, the 5.2 version has some exciting new tech that will improve Bluetooth headphones. Bluetooth LE Audio will let multiple devices share music or movies from a tablet, computer or phone. That is a major change as previously the sharing was limited to a maximum of two devices. This evolved technology your family might be able to watch the same movie on a tablet or listen to the same album on a phone, using Bluetooth headphones. This also would be good in public areas where multiple people can listen to the news or game on TV using their personal Bluetooth devices. Where previously you needed a connection splitter for folks to enjoy the same show at the same time, it is now possible to do the same wirelessly. Bluetooth for Audio amzn_assoc_placement = "adunit0"; amzn_assoc_tracking_id = "gow0e-20"; amzn_assoc_ad_mode = "search"; amzn_assoc_ad_type = "smart"; amzn_assoc_marketplace = "amazon"; amzn_assoc_region = "US"; amzn_assoc_default_search_phrase = "bluetooth earphones"; amzn_assoc_default_category = "All"; amzn_assoc_linkid = "a0ac43480cf818a6bb94dbdf7b54eb29"; amzn_assoc_search_bar = "false"; amzn_assoc_search_bar_position = "top"; amzn_assoc_title = "Bluetooth earphones"; amzn_assoc_placement = "adunit0"; amzn_assoc_tracking_id = "gow0e-20"; amzn_assoc_ad_mode = "search"; amzn_assoc_ad_type = "smart"; amzn_assoc_marketplace = "amazon"; amzn_assoc_region = "US"; amzn_assoc_default_search_phrase = "bluetooth headphones"; amzn_assoc_default_category = "All"; amzn_assoc_linkid = "a0ac43480cf818a6bb94dbdf7b54eb29"; amzn_assoc_search_bar = "false"; amzn_assoc_search_bar_position = "top"; amzn_assoc_title = "Bluetooth headphones"; amzn_assoc_placement = "adunit0"; amzn_assoc_tracking_id = "gow0e-20"; amzn_assoc_ad_mode = "search"; amzn_assoc_ad_type = "smart"; amzn_assoc_marketplace = "amazon"; amzn_assoc_region = "US"; amzn_assoc_default_search_phrase = "bluetooth speakers"; amzn_assoc_default_category = "All"; amzn_assoc_linkid = "a0ac43480cf818a6bb94dbdf7b54eb29"; amzn_assoc_search_bar = "false"; amzn_assoc_search_bar_position = "top"; amzn_assoc_title = "Bluetooth speakers"; Bluetooth usage beyond audio devices » Wireless mouse use with a computer as well as other peripherals such as wireless keyboards. I prefer using a mouse much more than the touchpad, and so when traveling for business, a Bluetooth powered mouse has been very useful and great to bring along. » Wireless control of and communication between a mobile phone and a Bluetooth compatible car stereo system. This way you can listen to any app containing music on your phone through the multiple speakers in your car. You are not tied down or stuck with only what is streaming through the radio. » Wireless communication between a smartphone and a smart lock for unlocking doors. When you are traveling and need to lock or unlock the door, Bluetoo tech makes it possible. Also can unlock the door when coming back with your luggage with just the phone without having to search for key.s » Use Bluetooth on the phone to determine if there are any wireless cameras in a hotel room. This is a great safety travel tip, especially when staying in rentals by owners. » Wireless streaming of audio to headphones with or without communication capabilities. » Wireless streaming of data collected by Bluetooth-enabled fitness devices to phone or PC » Transfer of files, contact details, calendar appointments, and reminders between devices.  » Enable remote communications for GPS receivers, medical equipment, bar code scanners, and traffic control devices. » Deliver advertisements using Bluetooth-enabled advertising technology to mobile phones, tablets, and laptops. » Game consoles such as Nintendo's Wii and Sony's PlayStation 3 use Bluetooth for their respective wireless controllers. » Short-range transmission of health sensor data from medical devices to a mobile phone » Real-time location systems are used to track and identify the location of objects in real-time. Tags such as the Tile or the TrackR use Bluetooth technology to find your missing item using wireless signals » Google uses data collected from travelers' Bluetooth devices to predict travel times and road congestion for motorists » Wireless transmission of audio (a more reliable alternative to FM transmitters) » Connection of motion controllers to a PC when using VR headsets » Bluetooth adapter (built-in or external dongle) for your laptop Bluetooth vs Wi-Fi TL;DR: Wi-Fi enables you to connect to the Internet, Bluetooth connects you to other devices (no Internet connection directly from it) Bluetooth and Wi-Fi have some similar applications: setting up networks, printing, or transferring files. Wi-Fi replaces high-speed cables that tie down your devices to a specific location when you are accessing local area networks in work areas or home to get onto the Internet. Bluetooth was intended for portable equipment and its applications. Bluetooth For Internet Acces These seem counterintuitive based on the information above, though you can use your Bluetooth-enabled cell phone as a modem for internet access on your laptop. So it still does not provide the actual service, instead, it sets up a connection. This is great in a pinch when there's no Wi-Fi service available or your regular internet service goes down. The main benefit of using Bluetooth instead of a USB cable for tethering is that you can keep your cell phone in your bag or pocket and still make the connection. Note that once your phone is being used as your laptop's access to the internet, all the data downloaded to and uploaded from your laptop is using your phone's data plan. Make sure that you have enough data available or that you have an unlimited data type of plan. Related articles: Top 5 Bluetooth Advancements From 2019 WTF are Noise Canceling Headphones? Sol Republic Amps Bluetooth Earbuds Review Is Bluetooth allowed on flights? Yes, based on the latest regulations you can have Bluetooth and Wi-Fi on while on an airplane. Until just a few years ago, Bluetooth headphones were effectively banned from commercial flights, as were all personal electronic devices that relied on a wireless connection. Of course, if you’ve flown in the past five years, you know that in late 2013 the Federal Aviation Administration eased many of its previous restrictions on portable devices during all phases of flight — including takeoff and landing. h2 {color: #000000; padding: 5px 15px 0px 7px; } .tabletop {color: #FFFFFF; padding: 5px 15px 0px 7px; text-align: center; background-color: #609c70; } .column_left { width: 35%; } .column_right { width: 65%; }

Airlines

Bluetooth Allowed

Air Canada

Yes

Air France

Yes

Alaska Airlines

Yes

British Airlines

Yes, not during takeoff & landing

Delta

Yes, not during takeoff & landing

JetBlue

Yes, not during takeoff & landing

Lufthansa

Yes

Ryanair

Yes

Southwest

Yes, not during takeoff & landing

Spirit

Yes

United Airlines

Yes

However, just because the FAA allows it doesn’t mean that your airline of choice doesn’t have its own rules and restrictions. So check with your airline before bringing and turning on your Bluetooth headphones. And no matter the restrictions on your Bluetooth use, you might still be required or asked to put the devices it is connected to into an Airplane Mode. In this case, you might need to have to re-enable Bluetooth connectivity after this mode is turned on. Just in case, it would be my advice, to also have wired earphones with you on your travel so you can still continue to enjoy your music and movies even if Bluetooth is not available.

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CIS 513 Week 5 Midterm Exam – Strayer NEW

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 http://budapp.net/CIS-513-Midterm-Exam-Week-5-Strayer-NEW-CIS513W5E.htm

 Chapter 1 Through 4

 Chapter 1 - Introduction to Wireless Communications

 TRUE/FALSE

      1.   VoIP phones can carry analog data over the Internet.

       2.   WirelessHD can transfer video and sound at 7 Gbps and higher.

       3.   UWB WiGig has a range of up to 100 meters.

       4.   The ZigBee Alliance protocols enable devices like light switches to communicate with one another.

       5.   RFID technology is implemented by roadside assistance services to link a vehicle and driver to a central service center.

       6.   4G technology uses 100% analog transmission for voice and data.

       7.   An AP connects wireless devices to the wired LAN.

       8.   DSL is an Internet access technology that uses cable TV lines to make a network connection.

       9.   The job market for wireless LAN professionals is saturated and likely to decline in coming years.

     10.   One advantage of wireless technology is that it is immune to interference sources.

  MULTIPLE CHOICE

      1.   What type of device is built into a tablet computer and can send data over radio waves to another device such as a laser printer?

a.

VoIP  phone

c.

access  point

b.

wireless  NIC

d.

Ethernet  NIC

        2.   How can VoIP over Wi-Fi help save money?

a.

by  eliminating the need for a phone

c.

by  reducing the cost of a smartphone

b.

by  saving on cellular phone bills

d.

by  not requiring an access point

        3.   Where would you most likely find RFID tags around the house?

a.

on  product packages

c.

in  the plumbing

b.

in  the walls and ceilings

d.

on  the electrical lines

        4.   What is the typical range for the use of Bluetooth?

a.

meters  to kilometers

c.

inches  to feet

b.

yards  to miles

d.

millimeters  to inches

         5.   With what technology will you find radio modules and link managers?

a.

RFID

c.

Wi-Fi

b.

GPS

d.

Bluetooth

        6.   Which technology has a maximum range of about 10 meters, can transmit up to 10 Gbps, and is used to transmit high quality audio and video wirelessly?

a.

Wi-Fi

c.

UWB

b.

Bluetooth

d.

RFID

        7.   Automatic connections between what type of devices create a piconet?

a.

VoIP

c.

Bluetooth

b.

Infrared

d.

WirelessHD

        8.   In what type of wireless communication device will you find a repeater?

a.

satellite

c.

antenna

b.

NFC

d.

WNIC

        9.   What kind of network is built around the concept of low-power transmitters built on towers that can use the same radio frequency channel?

a.

Wi-Fi  802.11 networks

c.

UWB  A/V networks

b.

cellular  telephone networks

d.

GPS  tracking networks

      10.   What type of cellular network uses 100 percent digital transmission for voice and data and can reach rates up to 150 Mbps?

a.

CDMA

c.

3G

b.

4G

d.

GSM

      11.   What kind of device does a WLAN use to facilitate communication between wireless computers?

a.

Ethernet  switch

c.

access  point

b.

GPS  hub

d.

cell  station

      12.   Which wireless standard provides for data transmission speeds up to 600 Mbps with a range up to 375 feet?

a.

802.11g

c.

802.16m

b.

WiGig

d.

802.11n

      13.   Which technology uses regular phone lines and transmits at speeds up to 256 Kbps?

a.

POTS

c.

T1

b.

ISDN

d.

cable  modem

      14.   Which communication technology should you use if you need to connect three offices which are all within 3 miles of each other at speeds up to 75 Mbps using antennas?

a.

T1

c.

WiMax

b.

DSL

d.

ISDN

      15.   Where are you most likely to find the WAP2 protocol in use?

a.

cellular  phones

c.

tablets

b.

laptops

d.

servers

      16.   What term refers to the combining of voice, video and text-processing and access to multiple network platforms from a single device?

a.

access  aggregation

c.

digital  convergence

b.

digital  landscape

d.

network  transparency

   COMPLETION

      1.   Smartphones can use software that allow them to make ______________  phone calls over a wireless LAN instead of the cellular network.

       2.   Bluetooth communicates using small, low-power ______________ called radio modules.

        3.   In the future, most barcode functions are likely to be replaced by ___________ tags including for the purpose of inventory management.

         4.   To protect confidentiality, wireless data can be ______________ between the access point and wireless device, allowing only the recipient to decode the message.

        5.   The FCC, FDA, and EPA have established ________ exposure safety guidelines to limit the signal absorption rate of wireless device users.

  MATCHING

  a.

3G

f.

motes

b.

Bluetooth

g.

T1

c.

DSL

h.

UWB

d.

J2ME

i.

WiGig

e.

link  manager

j.

WPAN

       1.   a wireless standard that enables devices to transmit data at up to 721.2 Kbps

over a typical maximum distance of 33 feet

      2.   a variation of the Java programming language designed for use in portable devices such as cellular phones

      3.   a very small network that typically extends to 10 meters or less

      4.   a technology used to transmit data over special telephone lines at 1.544 Mbps

      5.   an alliance of companies involved in developing a common wireless specification using the 60 GHz band

      6.   a technology used to transmit data over a telephone line

      7.   remote sensors used for collecting data from manufacturing equipment or for

scientific research

      8.   wireless communications technology that allows devices to transmit data at hundreds of megabits or even gigabits per second at short distances

      9.   a digital cellular technology that can send data at up to 21 Mbps over the cellular telephone network

    10.   special software in Bluetooth devices that helps identify other Bluetooth devices

  SHORT ANSWER

      1.   Describe how RFID can enhance a family’s convenience in the kitchen.

        2.   Describe Bluetooth technology and how it can be used in a computing environment.

       3.   What is UWB and how might it be used in a home?

        4.   What is a piconet?

        5.   What does a repeater do in a satellite communication system?

        6.   How does a WLAN use an access point?

      7.   Describe a WMAN and discuss a technology a WMAN might use.

       8.   What is digital convergence and how might it affect how people use network devices?

       9.   Discuss the use of wireless technologies in home entertainment.

     10.   Discuss how radio signal interference can affect wireless devices.

   Chapter 2 - Wireless Data Transmission

 TRUE/FALSE

      1.   The ASCII code uses 16 bits to represent 128 different characters.

       2.   Infrared light interferes with radio signals but is not affected by radio signals.

       3.   The height of a radio wave is called the amplitude of the wave.

       4.   Spread-spectrum signals are more susceptible to outside interference than narrow-band transmissions.

       5.   Hopping codes used in FHSS transmissions are configured on the base station by the network administrator.

  MULTIPLE CHOICE

      1.   Which of the following is true about wireless radio signal transmissions?

a.

they  travel at the speed of light

c.

they  travel as discrete particles

b.

they  require an atmosphere to move

d.

they  require visible light

        2.   Which of the following is NOT true about infrared light?

a.

it  can be used in directed transmissions

c.

it  is less susceptible to interference from visible light sources

b.

it  can be used in diffused transmissions

d.

all  infrared signals are invisible

        3.   Which of the following transmits a signal in an infrared device?

a.

diffuser

c.

detector

b.

emitter

d.

antenna

        4.   Which of the following is NOT a limitation of using infrared wireless systems?

a.

they  lack mobility

c.

someone  can eavesdrop from another room

b.

they  use a line-of-sight principle

d.

diffused  transmissions have a range of 50 feet

        5.   Which of the following is a good application for an infrared wireless system?

a.

stream  movies from a server

c.

whole  house wireless network

b.

wireless  outdoor speakers

d.

data  transfer between laptop and camera

        6.   Which best describes an analog signal?

a.

it  starts and stops

c.

consists  of discrete pulses

b.

intensity  varies and is continuous

d.

Morse  code is an example

        7.   What process must occur to transmit a digital signal over an analog medium?

a.

modulation

c.

decoding

b.

decoupling

d.

emitting

                                   1

      8.   The distance between a point in one wave cycle and the same point in the next wave cycle is called which of the following?

a.

amplitude

c.

carrier

b.

wavelength

d.

frequency

        9.   The frequency of a wave is best defined as which of the following?

a.

encoding  of bits onto an analog wave

c.

a carrier  wave that has been modulated

b.

the  voltage difference between the peak and trough of the wave

d.

the  number of times a cycle occurs within one second

      10.   What is the unit of measurement for radio frequency?

a.

volt

c.

Hz

b.

rpm

d.

amp

  3

    11.   What is the role of an antenna on a wireless device?

a.

it  receives data

c.

it  serves as a ground signal

b.

it  demodulates

d.

it  transmits and receives data

      12.   Which of the following is true about baud rate?

a.

only  one bit can be transferred per signal unit (baud)

c.

a  baud rate of 2400 always means a bandwidth of 2400 bps

b.

multiple  bits can be transferred with each signal unit

d.

multiple  signal units are needed to represent each bit

      13.   Which of the following best describes bandwidth in an analog system?

a.

the  range of frequencies that can be transmitted by a system

c.

the  number of bytes transmitted per minute

b.

the  number of bits transmitted per second

d.

the  maximum frequency supported by the medium

      14.   Which of the following is NOT a type of modulation that can be applied to an analog signal?

a.

phase

c.

frequency

b.

carrier

d.

amplitude

      15.   Which type of radio signal is most susceptible from interference sources such as lightning?

a.

AM

c.

PM

b.

FM

d.

DM

      16.   Which of the following is NOT an advantage of digital modulation over analog modulation?

a.

better  use of bandwidth

c.

better  performance during interference

b.

requires  less power

d.

modulation  techniques are simpler

      17.   Which binary signaling technique reduces the voltage to zero during the transmission of a 1 bit before the bit period ends.

a.

NRZ-L

c.

RZ

b.

NRZ-I

d.

NRZ

      18.   Which binary modulation technique employs NRZ coding such that the absence of a carrier signal represents a 0 bit?

a.

ASK

c.

FSK

b.

BPSK

d.

PSK

      19.   Which radio transmission method uses a chipping code?

a.

FM

c.

DSSS

b.

FHSS

d.

AM

      20.   Which of the following is a spread spectrum technique that employs mathematical algorithms to recover lost data bits?

a.

frequency  hopping

c.

narrow  band

b.

direct  sequence

d.

wide  band

   COMPLETION

      1.   Data signals in a wireless communication system travel on _______________ waves.

       2.   A signal that is broadcast as a continuous wave is called a(n) _______________ signal.

        3.   When representing a wave with a garden hose, the distance between the peaks of the waves represents the ____________.

        4.   The _______________ non-return-to-zero encoding method represents a 1 bit by increasing voltage to a positive value and a 0 bit by decreasing the voltage to a negative value.

        5.   In the presence of background interference, receivers can detect a ____________ change more reliably than a frequency or amplitude change.

   MATCHING

  a.

ASCII

f.

digital  modulation

b.

amplitude  modulation

g.

frequency  modulation

c.

analog  signal

h.

hopping  code

d.

baud  rate

i.

NRZ

e.

carrier  signal

j.

PM

       1.   a method of encoding a digital signal onto an analog carrier wave for transmission over media that does not support direct digital signal transmission

      2.   the number of times that a carrier signal changes per second

      3.   a technique that changes the number of wave cycles in response to a change in the amplitude of the input signal

      4.   a binary signaling technique that increases the voltage to represent a 1 bit but provides no voltage for a 0 bit

      5.   a technique that changes the height of a carrier wave in response to a change in the height of the input signal

      6.   a signal of a particular frequency that is modulated to contain either analog or digital data

      7.   a technique that changes the starting point of a wave cycle in response to a change in the amplitude of the input signal

      8.   the sequence of changing frequencies used in FHSS

      9.   a coding scheme that uses the numbers from 0 to 127 to represent alphanumeric characters and symbols

    10.   a signal in which the intensity (amplitude or voltage) varies continuously and smoothly over a period of time

  SHORT ANSWER

      1.   Describe the components in an infrared wireless system.

       2.   What are the advantages and limitations of an infrared wireless system?

       3.   Contrast analog signals with digital signals.

       4.   Describe how radio transmitters use a carrier signal.

       5.   How are radio waves transmitted using an antenna?

       6.   What are the three types of modulation that can be applied to an analog signal to enable it to carry information?

         7.   Describe amplitude modulation.

       8.   Describe the NRZ technique of representing bit signals.

       9.   What is phase shift keying?  Describe how it works.

     10.   How are bits transmitted using DSSS?  Include the chipping code in your answer.

   Chapter 3 - Radio Frequency Communications

 TRUE/FALSE

      1.   A high-pass filter allows all signals above a minimum threshold to pass through.

       2.   A mixer separates an input into two or more outputs.

       3.   TDMA was developed to overcome the problem of crosstalk.

       4.   A disadvantage of CDMA is that it can only carry one third the amount of data of TDMA.

       5.   There are no power limits imposed on devices using the unregulated bands.

  MULTIPLE CHOICE

      1.   Which of the following is NOT a common component of all radio systems?

a.

filter

c.

mixer  

b.

emitter

d.

antenna

        2.   Which of the following is a type of RF filter?

a.

top-pass

c.

bandpass

b.

mid-pass

d.

medipass

        3.   If a low-pass filter is set at 2200 MHz, which of the following signals would be allowed to pass through?

a.

2400  MHz

c.

1000  MHz

b.

1500  GHz

d.

23000  KHz

        4.   What kind of signals can result from the process of modulating a signal with data to be transmitted?

a.

harmonics

c.

modulators

b.

passbands

d.

sidebands

        5.   The sidebands of a frequency carrier are best described as which of the following?

a.

the  sum of the carrier signal and the highest value of the mixer output

c.

the  average of the high and low values of the input signal

b.

the  difference between the highest and lowest input frequency

d.

the  sum and difference of the highest input signal and carrier frequency

        6.   Which type of device is considered active device because it adds power to a signal?

a.

mixer

c.

antenna

b.

filter

d.

amplifier

        7.   Which of the following would take a transmission band of 1000 Hz and divide it into 100 channels of 10 Hz each to accommodate multiple access?

a.

FDMA

c.

CDMA

b.

TDMA

d.

SDMA

        8.   Which multiple access method overcomes the problem of crosstalk and divides the transmission time into several slots?

a.

SDMA

c.

TDMA

b.

CDMA

d.

FDMA

        9.   Which multiple access method uses a spreading code?

a.

CDMA

c.

SDMA

b.

TDMA

d.

FDMA

      10.   What type of transmission is a broadcast radio station an example of?

a.

duplex

c.

simplex

b.

half-simplex

d.

half-duplex

      11.   Which type of switching is used in a POTS system?

a.

packet  switching

c.

cellular  switching

b.

circuit  switching

d.

frame  switching

      12.   What can take place when signal strength falls close to or below the level of noise?

a.

SNR

c.

crosstalk

b.

interference

d.

attenuation

      13.   Objects in the path of a radio signal can cause which of the following?

a.

crosstalk

c.

EMI

b.

amplification

d.

attenuation

      14.   What is the term for signals that get reflected and travel different paths between transmitter and receiver arrive out of phase?

a.

electro-magnetic  interference

c.

multipath  distortion

b.

reflective  attenuation

d.

phase  misalignment

      15.   What problem can a directional antenna reduce in severity?

a.

reflective  attenuation

c.

phase  misalignment

b.

multipath  distortion

d.

electro-magnetic  interference

      16.   Which type of standard is an official standard controlled by and organization or body open to everyone?

a.

de  jure standards

c.

consortia  standards

b.

de  facto standards

d.

paramount  standards

      17.   Which standards organization functions as a clearinghouse for many types of standards development in the U.S.?

a.

ETSI

c.

ANSI

b.

IETF

d.

ISOC

      18.   Which standards body deals with user-premises equipment and satellite communications?

a.

IAB

c.

IETF

b.

TIA

d.

ISCO

      19.   Which international standards organization coordinates global communications networks and services and is actually a treaty organization?

a.

IAB

c.

ISO

b.

TIA

d.

ITU

      20.   In which frequency band will you find an 802.11 network?

a.

medium  frequency (MF)

c.

extremely  high frequency (EHF)

b.

super  high frequency (SHF)

d.

very  high frequency (VHF)

   COMPLETION

      1.   A __________________ filter sets a range of frequencies that include a minimum and maximum threshold.

       2.   _________________ uses direct sequence spread spectrum technology.

       3.   ____________________ transmission is typically used in consumer devices such as CB radios or walkie talkies where you have to hold down a button while speaking.

       4.   A technique called ______________ array processing replaces a traditional antenna

      5.   _______________ transmission uses low-power, precisely timed pulses of energy that operate in the same frequency spectrum as low-end noise and is used in WiGig.

  MATCHING

  a.

circuit  switching

f.

license  exempt spectrum

b.

directional  antenna

g.

packet  switching

c.

full-duplex  transmission

h.

signal-to-noise  ratio

d.

half-duplex  transmission

i.

simplex  transmission

e.

harmonics

j.

switching

       1.   transmission that occurs in both directions but only one way at a time

      2.   a switching technique in which a dedicated and direct physical connection is made between two transmitting devices

      3.   transmission that occurs in only one direction

      4.   unregulated radio frequency bands that are available in the United States to any users without a license

      5.   transmissions in which data flows in either direction simultaneously

      6.   moving a signal from one wire or frequency to another

      7.   data transmission that is broken into smaller units

      8.   an antenna that radiates the electromagnetic waves in one direction only

      9.   stray oscillations that result from the process of modulating a wave and that

fall outside the range of frequencies used for transmission

    10.   the measure of signal strength relative to the background noise

  SHORT ANSWER

      1.   What does a filter do and why is one needed in a radio system?

       2.   List the three types of RF filters.

       3.   Why are filters found in transmitters?

       4.   What is the purpose of a mixer?  Include a discussion of sidebands in your answer.

       5.   What is an amplifier and why is it a crucial component in a radio system?

       6.   Describe time division multiple access.

       7.   What are two advantages that TDMA has over FDMA?

       8.   What are three advantages of CDMA over TDMA?

       9.   What advantages does packet switching have over circuit switching for transmitting data?

     10.   What is multipath distortion?

   Chapter 4 - How Antennas Work

 TRUE/FALSE

      1.   Cables and connectors offer resistance to the flow of electricity, increasing the power of a signal.

       2.   Decibels are an absolute measurement of signal strength, making it simpler to calculate gain or loss.

       3.   The size of an antenna is directly proportional to the wavelength of the signal it is designed to transmit and receive.

       4.   A monopole antenna is a type of two-dimensional antenna.

       5.   Point-to-point wireless links are best served by using omnidirectional antennas.

  MULTIPLE CHOICE

      1.   Which of the following is likely to result in a wireless signal gain?

a.

cables

c.

connectors

b.

amplifier

d.

atmosphere

        2.   What unit of measurement is a ratio between two signal levels?

a.

volt

c.

decibel

b.

watt

d.

ohm

        3.   Which value indicates the signal being measured is twice the power?

a.

+3  dB

c.

+5  mW

b.

-5  dB

d.

-3  mW

        4.   If a signal is represented as 15 mW + 10 db, what is the resulting signal strength in mW?

a.

30  mW

c.

75  mW

b.

25  mW

d.

150  mW

        5.   Which of the following refers to the gain an antenna has over a dipole antenna at the same frequency?

a.

dBm

c.

dBi

b.

dBd

d.

dBg

        6.   Which of the following is true about antennas?

a.

the  size is proportional to the wavelength

c.

most  are active devices

b.

lower  frequency signals require larger antennas

d.

omnidirectional  types provide the best directional gain

        7.   Which of the following is true about omnidirectional antennas?

a.

they  work best in point-to-point links

c.

longer  ones usually have higher gain

b.

they  cannot be used in 802.11 applications

d.

they  emit a signal in three dimensions

        8.   Which type of directional antenna  is used for outdoor applications up to 16 miles?

a.

cellular

c.

parabolic  dish

b.

patch

d.

yagi

        9.   A cellular phone antenna that is 13 inches long would be considered which of the following?

a.

eighth-wave

c.

half-wave

b.

quarter-wave

d.

full-wave

      10.   If an antenna is much longer than the wavelength, what is the typical result?

a.

inefficient  delivery of RF energy

c.

wrong  signal frequency

b.

signals  that are an incorrect wavelength

d.

no  signal is transmitted

      11.   What does antenna polarization determine about the performance of the antenna?

a.

radiation  pattern

c.

measurement  of signals is positive or negative voltage

b.

horizontal  or vertical orientation

d.

direction  of the signal

      12.   What type of antenna is a straight piece of wire with no reflecting ground element?

a.

monopole

c.

horn

b.

dipole

d.

dish

      13.   Which type of antenna is two-dimensional, is common in telephone networks, and is used to transmit high-power microwave signals between towers?

a.

patch

c.

horn

b.

satellite  dish

d.

dipole

      14.   What type of antenna is divided into a matrix of radiating elements and are used in modern radar systems?

a.

switched  beam

c.

patch

b.

horn

d.

phased  array

      15.   When a coaxial cable connects the antenna to the transmitter, what property of the cable must match that of the antenna?

a.

impedance

c.

length

b.

thickness

d.

inductance

      16.   What type of wave propagation do RF signals transmitted at 50 MHz have?

a.

ground  waves

c.

line-of-sight  waves

b.

sky  waves

d.

atmospheric  waves

      17.   Which type of antenna should usually be used at the central location in a point-to-multipoint wireless link?

a.

unidirectional

c.

directional

b.

omnidirectional

d.

semi-directional

      18.   Which of the following is the elliptical region within which signals travel between two antennas in a point-to-point link?

a.

troposphere  radius

c.

Fresnel  zone

b.

propagation  limit

d.

wave  pattern

      19.   What is the signal strength necessary to meet a receiver’s minimum requirements?

a.

transmission  path

c.

minimum  wavelength

b.

Fresnel  zone

d.

link  budget

      20.   What is the maximum percent of the Fresnel zone that can be blocked by obstructions in a point-to-point link?

a.

20%

c.

40%

b.

60%

d.

10%

   COMPLETION

      1.    ______________ is the effect of an amplifier boosting the power of a signal.

       2.   A radio signal’s power does not change in a linear fashion, but instead changes ______________.

       3.   _____________ is a relative measurement used to represent gain or loss in a signal.

       4.   When considering antenna size, lower frequencies require ___________ antennas.

       5.   A _________________ analyzer is a tool that displays the signal amplitude and frequency of a radio transmission.

  MATCHING

  a.

antenna  pattern

f.

ground-plane

b.

dB  isotropic

g.

isotropic  radiator

c.

dBm

h.

passive  antenna

d.

dipole

i.

patch  antenna

e.

free  space loss

j.

smart  antenna

       1.   the signal loss that occurs as a result of the tendency of RF waves to spread

      2.   a theoretically perfect sphere that radiates power equally in all directions

      3.   the relative measurement of the gain of an antenna when compared to a theoretical isotropic radiator

      4.   a new type of antenna that uses a signal processor and an array of narrow beam elements

      5.   a graphic that shows how a signal radiates out of an antenna

      6.   a semi-directional antenna that emits a wide horizontal beam and an even

wider vertical beam

      7.   a metal disc or two straight wires assembled at 90 degrees, used to provide

a reflection point for monopole antennas

      8.   a relative way to indicate an absolute power level in the linear watt scale

      9.   can only radiate a signal with the same amount of energy that appears at the antenna connector

    10.   an antenna that has a fixed amount of gain over that of an isotropic radiator

  SHORT ANSWER

      1.   List three of the four aspects of RF signal transmission you need to know.

       2.   Describe the “tens and threes of RF mathematics”.

       3.   What is an isotropic radiator?

       4.   Describe directional gain and how it can be accomplished with a passive antenna.

       5.   What are two types of directional antenna?  Describe them.

       6.   What is free space loss?  Describe how it occurs.

       7.   How does the size of an antenna affect its ability to transmit and receive?

       8.   What does an antenna pattern show about the RF wave?

       9.   What does antenna polarization tell you about the antenna wave?  How is it important for signal reception?

     10.   Give two examples of two-dimensional antennas.  Describe them.

[distinguishedcollectorpatr-blog3]

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 Chapter 1 Through 4

 Chapter 1 - Introduction to Wireless Communications

 TRUE/FALSE

      1.   VoIP phones can carry analog data over the Internet.

       2.   WirelessHD can transfer video and sound at 7 Gbps and higher.

       3.   UWB WiGig has a range of up to 100 meters.

       4.   The ZigBee Alliance protocols enable devices like light switches to communicate with one another.

       5.   RFID technology is implemented by roadside assistance services to link a vehicle and driver to a central service center.

       6.   4G technology uses 100% analog transmission for voice and data.

       7.   An AP connects wireless devices to the wired LAN.

       8.   DSL is an Internet access technology that uses cable TV lines to make a network connection.

       9.   The job market for wireless LAN professionals is saturated and likely to decline in coming years.

     10.   One advantage of wireless technology is that it is immune to interference sources.

  MULTIPLE CHOICE

      1.   What type of device is built into a tablet computer and can send data over radio waves to another device such as a laser printer?

a.

VoIP  phone

c.

access  point

b.

wireless  NIC

d.

Ethernet  NIC

        2.   How can VoIP over Wi-Fi help save money?

a.

by  eliminating the need for a phone

c.

by  reducing the cost of a smartphone

b.

by  saving on cellular phone bills

d.

by  not requiring an access point

        3.   Where would you most likely find RFID tags around the house?

a.

on  product packages

c.

in  the plumbing

b.

in  the walls and ceilings

d.

on  the electrical lines

        4.   What is the typical range for the use of Bluetooth?

a.

meters  to kilometers

c.

inches  to feet

b.

yards  to miles

d.

millimeters  to inches

         5.   With what technology will you find radio modules and link managers?

a.

RFID

c.

Wi-Fi

b.

GPS

d.

Bluetooth

        6.   Which technology has a maximum range of about 10 meters, can transmit up to 10 Gbps, and is used to transmit high quality audio and video wirelessly?

a.

Wi-Fi

c.

UWB

b.

Bluetooth

d.

RFID

        7.   Automatic connections between what type of devices create a piconet?

a.

VoIP

c.

Bluetooth

b.

Infrared

d.

WirelessHD

        8.   In what type of wireless communication device will you find a repeater?

a.

satellite

c.

antenna

b.

NFC

d.

WNIC

        9.   What kind of network is built around the concept of low-power transmitters built on towers that can use the same radio frequency channel?

a.

Wi-Fi  802.11 networks

c.

UWB  A/V networks

b.

cellular  telephone networks

d.

GPS  tracking networks

      10.   What type of cellular network uses 100 percent digital transmission for voice and data and can reach rates up to 150 Mbps?

a.

CDMA

c.

3G

b.

4G

d.

GSM

      11.   What kind of device does a WLAN use to facilitate communication between wireless computers?

a.

Ethernet  switch

c.

access  point

b.

GPS  hub

d.

cell  station

      12.   Which wireless standard provides for data transmission speeds up to 600 Mbps with a range up to 375 feet?

a.

802.11g

c.

802.16m

b.

WiGig

d.

802.11n

      13.   Which technology uses regular phone lines and transmits at speeds up to 256 Kbps?

a.

POTS

c.

T1

b.

ISDN

d.

cable  modem

      14.   Which communication technology should you use if you need to connect three offices which are all within 3 miles of each other at speeds up to 75 Mbps using antennas?

a.

T1

c.

WiMax

b.

DSL

d.

ISDN

      15.   Where are you most likely to find the WAP2 protocol in use?

a.

cellular  phones

c.

tablets

b.

laptops

d.

servers

      16.   What term refers to the combining of voice, video and text-processing and access to multiple network platforms from a single device?

a.

access  aggregation

c.

digital  convergence

b.

digital  landscape

d.

network  transparency

   COMPLETION

      1.   Smartphones can use software that allow them to make ______________  phone calls over a wireless LAN instead of the cellular network.

       2.   Bluetooth communicates using small, low-power ______________ called radio modules.

        3.   In the future, most barcode functions are likely to be replaced by ___________ tags including for the purpose of inventory management.

         4.   To protect confidentiality, wireless data can be ______________ between the access point and wireless device, allowing only the recipient to decode the message.

        5.   The FCC, FDA, and EPA have established ________ exposure safety guidelines to limit the signal absorption rate of wireless device users.

  MATCHING

  a.

3G

f.

motes

b.

Bluetooth

g.

T1

c.

DSL

h.

UWB

d.

J2ME

i.

WiGig

e.

link  manager

j.

WPAN

       1.   a wireless standard that enables devices to transmit data at up to 721.2 Kbps

over a typical maximum distance of 33 feet

      2.   a variation of the Java programming language designed for use in portable devices such as cellular phones

      3.   a very small network that typically extends to 10 meters or less

      4.   a technology used to transmit data over special telephone lines at 1.544 Mbps

      5.   an alliance of companies involved in developing a common wireless specification using the 60 GHz band

      6.   a technology used to transmit data over a telephone line

      7.   remote sensors used for collecting data from manufacturing equipment or for

scientific research

      8.   wireless communications technology that allows devices to transmit data at hundreds of megabits or even gigabits per second at short distances

      9.   a digital cellular technology that can send data at up to 21 Mbps over the cellular telephone network

    10.   special software in Bluetooth devices that helps identify other Bluetooth devices

  SHORT ANSWER

      1.   Describe how RFID can enhance a family’s convenience in the kitchen.

        2.   Describe Bluetooth technology and how it can be used in a computing environment.

       3.   What is UWB and how might it be used in a home?

        4.   What is a piconet?

        5.   What does a repeater do in a satellite communication system?

        6.   How does a WLAN use an access point?

      7.   Describe a WMAN and discuss a technology a WMAN might use.

       8.   What is digital convergence and how might it affect how people use network devices?

       9.   Discuss the use of wireless technologies in home entertainment.

     10.   Discuss how radio signal interference can affect wireless devices.

   Chapter 2 - Wireless Data Transmission

 TRUE/FALSE

      1.   The ASCII code uses 16 bits to represent 128 different characters.

       2.   Infrared light interferes with radio signals but is not affected by radio signals.

       3.   The height of a radio wave is called the amplitude of the wave.

       4.   Spread-spectrum signals are more susceptible to outside interference than narrow-band transmissions.

       5.   Hopping codes used in FHSS transmissions are configured on the base station by the network administrator.

  MULTIPLE CHOICE

      1.   Which of the following is true about wireless radio signal transmissions?

a.

they  travel at the speed of light

c.

they  travel as discrete particles

b.

they  require an atmosphere to move

d.

they  require visible light

        2.   Which of the following is NOT true about infrared light?

a.

it  can be used in directed transmissions

c.

it  is less susceptible to interference from visible light sources

b.

it  can be used in diffused transmissions

d.

all  infrared signals are invisible

        3.   Which of the following transmits a signal in an infrared device?

a.

diffuser

c.

detector

b.

emitter

d.

antenna

        4.   Which of the following is NOT a limitation of using infrared wireless systems?

a.

they  lack mobility

c.

someone  can eavesdrop from another room

b.

they  use a line-of-sight principle

d.

diffused  transmissions have a range of 50 feet

        5.   Which of the following is a good application for an infrared wireless system?

a.

stream  movies from a server

c.

whole  house wireless network

b.

wireless  outdoor speakers

d.

data  transfer between laptop and camera

        6.   Which best describes an analog signal?

a.

it  starts and stops

c.

consists  of discrete pulses

b.

intensity  varies and is continuous

d.

Morse  code is an example

        7.   What process must occur to transmit a digital signal over an analog medium?

a.

modulation

c.

decoding

b.

decoupling

d.

emitting

                                   1

      8.   The distance between a point in one wave cycle and the same point in the next wave cycle is called which of the following?

a.

amplitude

c.

carrier

b.

wavelength

d.

frequency

        9.   The frequency of a wave is best defined as which of the following?

a.

encoding  of bits onto an analog wave

c.

a carrier  wave that has been modulated

b.

the  voltage difference between the peak and trough of the wave

d.

the  number of times a cycle occurs within one second

      10.   What is the unit of measurement for radio frequency?

a.

volt

c.

Hz

b.

rpm

d.

amp

  3

    11.   What is the role of an antenna on a wireless device?

a.

it  receives data

c.

it  serves as a ground signal

b.

it  demodulates

d.

it  transmits and receives data

      12.   Which of the following is true about baud rate?

a.

only  one bit can be transferred per signal unit (baud)

c.

a  baud rate of 2400 always means a bandwidth of 2400 bps

b.

multiple  bits can be transferred with each signal unit

d.

multiple  signal units are needed to represent each bit

      13.   Which of the following best describes bandwidth in an analog system?

a.

the  range of frequencies that can be transmitted by a system

c.

the  number of bytes transmitted per minute

b.

the  number of bits transmitted per second

d.

the  maximum frequency supported by the medium

      14.   Which of the following is NOT a type of modulation that can be applied to an analog signal?

a.

phase

c.

frequency

b.

carrier

d.

amplitude

      15.   Which type of radio signal is most susceptible from interference sources such as lightning?

a.

AM

c.

PM

b.

FM

d.

DM

      16.   Which of the following is NOT an advantage of digital modulation over analog modulation?

a.

better  use of bandwidth

c.

better  performance during interference

b.

requires  less power

d.

modulation  techniques are simpler

      17.   Which binary signaling technique reduces the voltage to zero during the transmission of a 1 bit before the bit period ends.

a.

NRZ-L

c.

RZ

b.

NRZ-I

d.

NRZ

      18.   Which binary modulation technique employs NRZ coding such that the absence of a carrier signal represents a 0 bit?

a.

ASK

c.

FSK

b.

BPSK

d.

PSK

      19.   Which radio transmission method uses a chipping code?

a.

FM

c.

DSSS

b.

FHSS

d.

AM

      20.   Which of the following is a spread spectrum technique that employs mathematical algorithms to recover lost data bits?

a.

frequency  hopping

c.

narrow  band

b.

direct  sequence

d.

wide  band

   COMPLETION

      1.   Data signals in a wireless communication system travel on _______________ waves.

       2.   A signal that is broadcast as a continuous wave is called a(n) _______________ signal.

        3.   When representing a wave with a garden hose, the distance between the peaks of the waves represents the ____________.

        4.   The _______________ non-return-to-zero encoding method represents a 1 bit by increasing voltage to a positive value and a 0 bit by decreasing the voltage to a negative value.

        5.   In the presence of background interference, receivers can detect a ____________ change more reliably than a frequency or amplitude change.

   MATCHING

  a.

ASCII

f.

digital  modulation

b.

amplitude  modulation

g.

frequency  modulation

c.

analog  signal

h.

hopping  code

d.

baud  rate

i.

NRZ

e.

carrier  signal

j.

PM

       1.   a method of encoding a digital signal onto an analog carrier wave for transmission over media that does not support direct digital signal transmission

      2.   the number of times that a carrier signal changes per second

      3.   a technique that changes the number of wave cycles in response to a change in the amplitude of the input signal

      4.   a binary signaling technique that increases the voltage to represent a 1 bit but provides no voltage for a 0 bit

      5.   a technique that changes the height of a carrier wave in response to a change in the height of the input signal

      6.   a signal of a particular frequency that is modulated to contain either analog or digital data

      7.   a technique that changes the starting point of a wave cycle in response to a change in the amplitude of the input signal

      8.   the sequence of changing frequencies used in FHSS

      9.   a coding scheme that uses the numbers from 0 to 127 to represent alphanumeric characters and symbols

    10.   a signal in which the intensity (amplitude or voltage) varies continuously and smoothly over a period of time

  SHORT ANSWER

      1.   Describe the components in an infrared wireless system.

       2.   What are the advantages and limitations of an infrared wireless system?

       3.   Contrast analog signals with digital signals.

       4.   Describe how radio transmitters use a carrier signal.

       5.   How are radio waves transmitted using an antenna?

       6.   What are the three types of modulation that can be applied to an analog signal to enable it to carry information?

         7.   Describe amplitude modulation.

       8.   Describe the NRZ technique of representing bit signals.

       9.   What is phase shift keying?  Describe how it works.

     10.   How are bits transmitted using DSSS?  Include the chipping code in your answer.

   Chapter 3 - Radio Frequency Communications

 TRUE/FALSE

      1.   A high-pass filter allows all signals above a minimum threshold to pass through.

       2.   A mixer separates an input into two or more outputs.

       3.   TDMA was developed to overcome the problem of crosstalk.

       4.   A disadvantage of CDMA is that it can only carry one third the amount of data of TDMA.

       5.   There are no power limits imposed on devices using the unregulated bands.

  MULTIPLE CHOICE

      1.   Which of the following is NOT a common component of all radio systems?

a.

filter

c.

mixer  

b.

emitter

d.

antenna

        2.   Which of the following is a type of RF filter?

a.

top-pass

c.

bandpass

b.

mid-pass

d.

medipass

        3.   If a low-pass filter is set at 2200 MHz, which of the following signals would be allowed to pass through?

a.

2400  MHz

c.

1000  MHz

b.

1500  GHz

d.

23000  KHz

        4.   What kind of signals can result from the process of modulating a signal with data to be transmitted?

a.

harmonics

c.

modulators

b.

passbands

d.

sidebands

        5.   The sidebands of a frequency carrier are best described as which of the following?

a.

the  sum of the carrier signal and the highest value of the mixer output

c.

the  average of the high and low values of the input signal

b.

the  difference between the highest and lowest input frequency

d.

the  sum and difference of the highest input signal and carrier frequency

        6.   Which type of device is considered active device because it adds power to a signal?

a.

mixer

c.

antenna

b.

filter

d.

amplifier

        7.   Which of the following would take a transmission band of 1000 Hz and divide it into 100 channels of 10 Hz each to accommodate multiple access?

a.

FDMA

c.

CDMA

b.

TDMA

d.

SDMA

        8.   Which multiple access method overcomes the problem of crosstalk and divides the transmission time into several slots?

a.

SDMA

c.

TDMA

b.

CDMA

d.

FDMA

        9.   Which multiple access method uses a spreading code?

a.

CDMA

c.

SDMA

b.

TDMA

d.

FDMA

      10.   What type of transmission is a broadcast radio station an example of?

a.

duplex

c.

simplex

b.

half-simplex

d.

half-duplex

      11.   Which type of switching is used in a POTS system?

a.

packet  switching

c.

cellular  switching

b.

circuit  switching

d.

frame  switching

      12.   What can take place when signal strength falls close to or below the level of noise?

a.

SNR

c.

crosstalk

b.

interference

d.

attenuation

      13.   Objects in the path of a radio signal can cause which of the following?

a.

crosstalk

c.

EMI

b.

amplification

d.

attenuation

      14.   What is the term for signals that get reflected and travel different paths between transmitter and receiver arrive out of phase?

a.

electro-magnetic  interference

c.

multipath  distortion

b.

reflective  attenuation

d.

phase  misalignment

      15.   What problem can a directional antenna reduce in severity?

a.

reflective  attenuation

c.

phase  misalignment

b.

multipath  distortion

d.

electro-magnetic  interference

      16.   Which type of standard is an official standard controlled by and organization or body open to everyone?

a.

de  jure standards

c.

consortia  standards

b.

de  facto standards

d.

paramount  standards

      17.   Which standards organization functions as a clearinghouse for many types of standards development in the U.S.?

a.

ETSI

c.

ANSI

b.

IETF

d.

ISOC

      18.   Which standards body deals with user-premises equipment and satellite communications?

a.

IAB

c.

IETF

b.

TIA

d.

ISCO

      19.   Which international standards organization coordinates global communications networks and services and is actually a treaty organization?

a.

IAB

c.

ISO

b.

TIA

d.

ITU

      20.   In which frequency band will you find an 802.11 network?

a.

medium  frequency (MF)

c.

extremely  high frequency (EHF)

b.

super  high frequency (SHF)

d.

very  high frequency (VHF)

   COMPLETION

      1.   A __________________ filter sets a range of frequencies that include a minimum and maximum threshold.

       2.   _________________ uses direct sequence spread spectrum technology.

       3.   ____________________ transmission is typically used in consumer devices such as CB radios or walkie talkies where you have to hold down a button while speaking.

       4.   A technique called ______________ array processing replaces a traditional antenna

      5.   _______________ transmission uses low-power, precisely timed pulses of energy that operate in the same frequency spectrum as low-end noise and is used in WiGig.

  MATCHING

  a.

circuit  switching

f.

license  exempt spectrum

b.

directional  antenna

g.

packet  switching

c.

full-duplex  transmission

h.

signal-to-noise  ratio

d.

half-duplex  transmission

i.

simplex  transmission

e.

harmonics

j.

switching

       1.   transmission that occurs in both directions but only one way at a time

      2.   a switching technique in which a dedicated and direct physical connection is made between two transmitting devices

      3.   transmission that occurs in only one direction

      4.   unregulated radio frequency bands that are available in the United States to any users without a license

      5.   transmissions in which data flows in either direction simultaneously

      6.   moving a signal from one wire or frequency to another

      7.   data transmission that is broken into smaller units

      8.   an antenna that radiates the electromagnetic waves in one direction only

      9.   stray oscillations that result from the process of modulating a wave and that

fall outside the range of frequencies used for transmission

    10.   the measure of signal strength relative to the background noise

  SHORT ANSWER

      1.   What does a filter do and why is one needed in a radio system?

       2.   List the three types of RF filters.

       3.   Why are filters found in transmitters?

       4.   What is the purpose of a mixer?  Include a discussion of sidebands in your answer.

       5.   What is an amplifier and why is it a crucial component in a radio system?

       6.   Describe time division multiple access.

       7.   What are two advantages that TDMA has over FDMA?

       8.   What are three advantages of CDMA over TDMA?

       9.   What advantages does packet switching have over circuit switching for transmitting data?

     10.   What is multipath distortion?

   Chapter 4 - How Antennas Work

 TRUE/FALSE

      1.   Cables and connectors offer resistance to the flow of electricity, increasing the power of a signal.

       2.   Decibels are an absolute measurement of signal strength, making it simpler to calculate gain or loss.

       3.   The size of an antenna is directly proportional to the wavelength of the signal it is designed to transmit and receive.

       4.   A monopole antenna is a type of two-dimensional antenna.

       5.   Point-to-point wireless links are best served by using omnidirectional antennas.

  MULTIPLE CHOICE

      1.   Which of the following is likely to result in a wireless signal gain?

a.

cables

c.

connectors

b.

amplifier

d.

atmosphere

        2.   What unit of measurement is a ratio between two signal levels?

a.

volt

c.

decibel

b.

watt

d.

ohm

        3.   Which value indicates the signal being measured is twice the power?

a.

+3  dB

c.

+5  mW

b.

-5  dB

d.

-3  mW

        4.   If a signal is represented as 15 mW + 10 db, what is the resulting signal strength in mW?

a.

30  mW

c.

75  mW

b.

25  mW

d.

150  mW

        5.   Which of the following refers to the gain an antenna has over a dipole antenna at the same frequency?

a.

dBm

c.

dBi

b.

dBd

d.

dBg

        6.   Which of the following is true about antennas?

a.

the  size is proportional to the wavelength

c.

most  are active devices

b.

lower  frequency signals require larger antennas

d.

omnidirectional  types provide the best directional gain

        7.   Which of the following is true about omnidirectional antennas?

a.

they  work best in point-to-point links

c.

longer  ones usually have higher gain

b.

they  cannot be used in 802.11 applications

d.

they  emit a signal in three dimensions

        8.   Which type of directional antenna  is used for outdoor applications up to 16 miles?

a.

cellular

c.

parabolic  dish

b.

patch

d.

yagi

        9.   A cellular phone antenna that is 13 inches long would be considered which of the following?

a.

eighth-wave

c.

half-wave

b.

quarter-wave

d.

full-wave

      10.   If an antenna is much longer than the wavelength, what is the typical result?

a.

inefficient  delivery of RF energy

c.

wrong  signal frequency

b.

signals  that are an incorrect wavelength

d.

no  signal is transmitted

      11.   What does antenna polarization determine about the performance of the antenna?

a.

radiation  pattern

c.

measurement  of signals is positive or negative voltage

b.

horizontal  or vertical orientation

d.

direction  of the signal

      12.   What type of antenna is a straight piece of wire with no reflecting ground element?

a.

monopole

c.

horn

b.

dipole

d.

dish

      13.   Which type of antenna is two-dimensional, is common in telephone networks, and is used to transmit high-power microwave signals between towers?

a.

patch

c.

horn

b.

satellite  dish

d.

dipole

      14.   What type of antenna is divided into a matrix of radiating elements and are used in modern radar systems?

a.

switched  beam

c.

patch

b.

horn

d.

phased  array

      15.   When a coaxial cable connects the antenna to the transmitter, what property of the cable must match that of the antenna?

a.

impedance

c.

length

b.

thickness

d.

inductance

      16.   What type of wave propagation do RF signals transmitted at 50 MHz have?

a.

ground  waves

c.

line-of-sight  waves

b.

sky  waves

d.

atmospheric  waves

      17.   Which type of antenna should usually be used at the central location in a point-to-multipoint wireless link?

a.

unidirectional

c.

directional

b.

omnidirectional

d.

semi-directional

      18.   Which of the following is the elliptical region within which signals travel between two antennas in a point-to-point link?

a.

troposphere  radius

c.

Fresnel  zone

b.

propagation  limit

d.

wave  pattern

      19.   What is the signal strength necessary to meet a receiver’s minimum requirements?

a.

transmission  path

c.

minimum  wavelength

b.

Fresnel  zone

d.

link  budget

      20.   What is the maximum percent of the Fresnel zone that can be blocked by obstructions in a point-to-point link?

a.

20%

c.

40%

b.

60%

d.

10%

   COMPLETION

      1.    ______________ is the effect of an amplifier boosting the power of a signal.

       2.   A radio signal’s power does not change in a linear fashion, but instead changes ______________.

       3.   _____________ is a relative measurement used to represent gain or loss in a signal.

       4.   When considering antenna size, lower frequencies require ___________ antennas.

       5.   A _________________ analyzer is a tool that displays the signal amplitude and frequency of a radio transmission.

  MATCHING

  a.

antenna  pattern

f.

ground-plane

b.

dB  isotropic

g.

isotropic  radiator

c.

dBm

h.

passive  antenna

d.

dipole

i.

patch  antenna

e.

free  space loss

j.

smart  antenna

       1.   the signal loss that occurs as a result of the tendency of RF waves to spread

      2.   a theoretically perfect sphere that radiates power equally in all directions

      3.   the relative measurement of the gain of an antenna when compared to a theoretical isotropic radiator

      4.   a new type of antenna that uses a signal processor and an array of narrow beam elements

      5.   a graphic that shows how a signal radiates out of an antenna

      6.   a semi-directional antenna that emits a wide horizontal beam and an even

wider vertical beam

      7.   a metal disc or two straight wires assembled at 90 degrees, used to provide

a reflection point for monopole antennas

      8.   a relative way to indicate an absolute power level in the linear watt scale

      9.   can only radiate a signal with the same amount of energy that appears at the antenna connector

    10.   an antenna that has a fixed amount of gain over that of an isotropic radiator

  SHORT ANSWER

      1.   List three of the four aspects of RF signal transmission you need to know.

       2.   Describe the “tens and threes of RF mathematics”.

       3.   What is an isotropic radiator?

       4.   Describe directional gain and how it can be accomplished with a passive antenna.

       5.   What are two types of directional antenna?  Describe them.

       6.   What is free space loss?  Describe how it occurs.

       7.   How does the size of an antenna affect its ability to transmit and receive?

       8.   What does an antenna pattern show about the RF wave?

       9.   What does antenna polarization tell you about the antenna wave?  How is it important for signal reception?

     10.   Give two examples of two-dimensional antennas.  Describe them.