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antennaexperts · 2 years ago

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Everything You Need to Know about FM broadcast antenna

Antennas come in different shapes and sizes. Every antenna performs differently from another. Choosing the right kind of antenna is very important for gaining better performance. FM Broadcast Antennas help to receive high-quality FM broadcasts. They also help to receive strong indoor signals.

Antennas designed with bands between 88 MHz and 108 MHz are good for receiving the FM broadcast. They also give the most effective FM reception. In this blog, we will discuss everything related to FM broadcast antenna and its features, benefits, and how it works.

Basics of Dipole antenna

Before we discuss the different features of a dipole antenna, it is necessary to learn its basics. Dipole Antennas contain two parts or poles. In a half-wave dipole, each leg is an electrical quarter wavelength long.

The length of the dipole is determined by the frequency operation. FM broadcast band extends from 87.5 MHz to 108 MHz. Coaxial cable is used for a balun in this type of antenna. The outer shield is attached to the earth and the antenna is balanced.

In a dipole antenna, the inner conductor of the coax is attached to one leg of the dipole and the outer conductor of the coax is connected to the antenna’s other leg.

FM interference

Problems of FM interference occur often when the distance between the transmitting and receiving antenna is increased. Tropospheric scatter causes parts of the FM transmissions to be retracted towards the earth at some distance within a normal line of sight.

This phenomenon occurs when a temperature inversion is located in the FM broadcast signal path. These signal refractions create FM reception. They can also disrupt the reception of FM broadcast transmission.

Obstructions to FM broadcast signals can range from small hills and buildings to mountains. The resultant effects could be partial absorption that reduces received signal strength. Multipath interference distorts the FM signals resulting in low-fidelity reception.

Steps to develop FM dipole antenna

It is very simple to design an FM dipole antenna. You will need some basic accessories to make this antenna such as:

Wrap to secure the center of the diploe and prevent the flex from opening out

Twin flex of old speaker

String or twine to secure the ends of the dipole to fixing points

Connectors connected to the coaxial cable

One of the major benefits of using mains flex is that it is used as a feeder for radio frequency signals. This wire is a close approximation to 75 ohms or a twin or open wire feeder. FM dipole antenna can be made with the help of a cheap speaker wire.

To design a VHF FM dipole antenna, the cable must have the two insulated wires split back away from one another and opened out. The next step is to secure the center to prevent the cable to open out. You can use a wrap that is available in most electronics components stockiest. You can use the length of the wire as the feeder for the antenna.

You must keep the length of the antenna at about 150 cm. Then you can knot the ends of the wire to attach it to some string. The knotting of the wire adds some inductance to the wire ends.

While installing the antenna in a roof space, keep it away from all the objects made of metal. The ends of the antenna are more sensitive to metal objects.

Common types of outdoor FM broadcast antennas

Now, we will discuss the common types of FM broadcast antennas in this section.

1. Crossed dipole or Turnstile

This Circular Polarization Antenna provides an omnidirectional receive pattern. It has low gain in all the planes.

2. Unidirectional dipole

The next type of outdoor FM Broadcast Antenna is a unidirectional dipole. It is a large dipole with two elements and more gain than the common indoor twin lead dipole. This dipole antenna emits the signals in one direction.

3. Multi-element array

This is a kind of unidirectional antenna that can receive distant stations because of high gain. This gain is directional and needs an antenna to be rotated.

Types of Indoor FM antennas

Many urban and near-suburban areas cannot install an outdoor antenna. In these areas, an indoor FM antenna can be installed. Let us have a look at the kinds of Indoor FM antennas:

Amplified indoor antenna

Amplified antenna designs have inherent tradeoffs in signal-to-noise and other negative RF attributes.

Unamplified indoor antenna

The unamplified indoor antenna has two basic antenna configurations.

½ wave vertical

This vertical antenna has a high gain for an indoor antenna. It provides high-quality FM reception in urban areas.

Bidirectional dipole

These Directional Antennas are commonly used indoor FM antennas. Single, dipole design and ½ waves exist as an industry gain reference for most FM broadcast band antennas. It gives signals from all directions.

Benefits of using FM broadcast antenna

We discussed the different types of Horizontally Polarized Antennas. Now, let us have a look at the benefits of Omni directional Antennas.

FM broadcast antenna is very easy to install and set up in urban areas and stations.

These Circular polarized Antennas never rust or get damaged due to sun rays, winds, water, or snow. They work for a long time and give better performance than normal antennas.

Vertically Polarized Antennas give high-quality FM broadcasts.

It is easy to use these antennas without any professional guidance.

Yagi Antenna give strong signals in all areas and directions.

These antennas are cost-effective and give stronger signals than other types of antennas.

One can design an FM broadcast antenna with the help of some basic materials.

Read more: Advantages and Disadvantages of Yagi Antenna

Where to find the best quality FM broadcast antenna?

Today, it is easy to get the best quality FM broadcast antennas from online sites. You can check the official site of FM Broadcast Antennas Manufacturer on Google engine. Some companies provide a long-term warranty on FM broadcast antennae to their regular customers.

#FM Broadcast Antennas #Dipole Antennas #FM Broadcast Antenna #Directional Antennas #Horizontally Polarized Antennas #Omni directional Antennas #Vertically Polarized Antennas #FM Broadcast Antennas Manufacturer

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certainheartrunaway · 4 years ago

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Current Ham Radio News

Many thanks to SWLing Post contributor, Ralf Bender, who shares the following notice from Channel 292: A heavy storm that hit us Saturday afternoon, caused severe damage to our antennas. Since Saturday, 1528 UTC we are off air. We hope that we can repair some of the damages on Sunday, and to be back on […]

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Radio Waves: Stories Making Waves in the World of Radio Because I keep my ear to the waves, as well as receive many tips from others who do the same, I find myself privy to radio-related stories that might interest SWLing Post readers. To that end: Welcome to the SWLing Post’s Radio Waves, a collection of links to interesting […]

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A25RU Team will be active from Botswana, 14 - 26 March 2021.

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“Oggie Harry Rundall, AC3EK, wrote to me about an experience he had setting compression on his Icom IC-7300. That prompted me to investigate some history, show how compression is set on the IC-7300, and provide example voice recordings.”

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1. Contest sponsors The “Soyuz Radioljubitelej Rossii” (Union of Radioamateurs of Russia), SRR is pleased to announce 28 International “Russian DX Contest”

2. Contest dates, bands, and modes

1200 UTC 20 March till 1159 UTC 21 March 2021

160, 80, 40, 20, 15 and 10 meters. No contest QSOs on WARC bands;

CW and Phone.

3. Entry categories:

SOAB–MIX – Single Op, All Bands, MIXED

SOAB–MIX-LP – Single Op, All Bands, MIXED, Low Power 100 watts

SOAB-MIX-QRP – Single Op, All Bands, MIXED, QRP 5 watts

SOAB–CW – Single Op, All Bands, CW

SOAB–CW–LP – Single Op, All Bands, CW, Low Power 100 watts

SOAB–SSB – Single Op, All Bands, SSB

SOAB–SSB-LP – Single Op, All Bands, SSB, Low Power 100 watts

SOSB – Single Op, single band, MIXED (6 different band entries, separately 160, 80, 40, 20, 15, 10 m)

MOST – Multi Op, All Bands, Single transmitter, MIXED

MO2T – Multi Op, Two transmitters, MIXED

MM – Multi Op, Multi transmitters, MIXED

SWL – MIXED

3.1 The participant can operate and submit the log for two different single band categories to be eligible for awards, for instance, 10m and 80m as per 11.3.

3.2 SOSB entrants may operate on other bands during the contest and are encouraged to submit their entire logs to help in the log cross-checking process. These contacts will not affect the SOSB score but will be credited to other stations.

3.3 Results will be listed separately for European Russia, Asiatic Russia and by each continent.

4. Intentionally left blank

5. General Rules 5.1. All transmitters, receivers, and amplifiers must be within a single 500-meter diameter circle. Antennas must be physically connected by RF transmission lines to the transmitters and receivers, except as described in 5.1.5.

5.1.1. Remote operation is permitted if the physical location of all transmitters, receivers, and antennas are at one station location as described in 5.1. A remotely operated station must obey all station license, operator license, and category limitations. The call sign used must be one issued or permitted by the Regulatory Authority of the station location.

5.1.2. The use of QSO finding assistance (DX cluster, CW Skimmer etc) is allowed for all entries.

5.1.3. The use of any calls other than participant’s for any reason including keeping the run frequency on any band, making schedules, DX-spotting, moving the multipliers is prohibited.

5.1.4. Self-spotting or soliciting contacts by any means other than amateur radio is prohibited.

5.1.5. The use of one and only one remote receiver located within 25 kilometers of the main transmitter site is permitted, in addition to the receiver at the transmitter site is allowed for all entries.

5.1.6. The use of any remote receivers other than described in 5.1.5 are prohibited. Violators will be subject to disqualification.

5.2. Single Operator participants may change bands and modes without restrictions. Only one signal can be transmitted at any given time.

5.2.1. Single Operator categories: one person (the operator) performs all operating, logging and spotting functions. Any assistance will result in reclassification into the Multi Operator category or disqualification at the discretion of the contest committee.

5.3. MOST stations are subject to a 10 minutes band change rule. Mode change within current band is allowed without limitations.

5.3.1. Start time is determined by the time of the first QSO made on the band. The band may be changed after 10 full minutes have elapsed.

5.3.2. Only one signal can be transmitted at any given time. Exception: two signals on two different bands are allowed if (and only if) the station on another (and only one) “multiplier” band works a new multiplier.

5.3.3. The “multiplier” transmitter is subject to its own 10 minute rule for band changes as described in 5.3.1.

5.3.4. Contacts which violate band change rules, should be clearly marked in the log with an X-QSO: key (as per 11.11 ). They will neither be counted nor penalized for an entrant, but will be counted for the station contacted.

5.3.5. Tampering with the QSO time to comply with the 10 minute rule (“rubber clocking”) will result in disqualification.

5.4. MO2T (Multi Op, Two transmitters): A maximum of two transmitted signals at any time on different bands. Each transmitter may make a maximum of 8 band changes in any clock hour (00 through 59 minutes). For example, a change from 40 meters to 80 meters and then back to 40 meters constitutes two band changes. Both transmitters may work any and all stations. A station may be worked twice per band (CW and SSB) regardless of which transmitter is used.

5.5. MM (Multi Op, Multi transmitters): A maximum of six transmitted signals, one per band at any one time. All equipment (transmitters, receivers, amplifiers, antennas, etc.) must be located in same DXCC entity, including remotely controlled equipment. Six bands may be activated simultaneously. Use a separate serial number sequence for each band. Limits in 5.1 do not apply.

5.6. All MIXED categories entrants can work the same station twice per band (CW and SSB).

6. Exchange: 6.1. Non-Russian stations: signal report + QSO number, starting with 001.

6.2. Multioperator (MOST, MO2T, MM) may alternativley use separate serial numbers for each band.

6.3. Russian stations: signal report + oblast code as per attached list.

7. QSO Points. 7.1. Russian stations:

QSO with your own country (Russia on your continent) – 2 points,

QSO with Russia on another continent – 5 points,

QSO with a different country on your continent – 3 points,

QSO with another continent – 5 points.

7.2. Non-Russian stations:

QSO with Russian station – 10 points,

QSO with your own country – 2 points,

QSO with a different country on your continent – 3 points,

QSO with another continent – 5 points.

7.3. Kaliningrad (UA2F), Franz Josef Land (RI1FJ) and Russian Antarctic stations (RI1AN) each count as a separate DXCC entity and a separate Oblast (double multiplier) with Kaliningrad counts as European Russia for scoring purposes.

7.4. Maritime mobile (“/MM”) stations do not count as multipliers and score 5 points for all participants.

7.5. SWL points are calculated along the same principles as described in 7.1 and 7.2.

8. Dupes 8.1. Dupes are contacts made with the same station on the same band and mode. If the first contact between stations is valid, dupes have 0 points value. If the first contact is not valid, then second (dupe) contact is accepted.

8.2. Dupe contacts are not penalized; they do not have to be marked in the log. All entrants are strongly recommended to leave DUPES in the log.

9. Multipliers There are two types of multipliers:

One multiplier for each different oblast contacted on each band, including UA2F, RI1FJ and RI1AN as per 7.3.

One multiplier for each different country (DXCC entity list + WAE multipliers list) contacted on each band.

10. Final Score 10.1. The final score is the result of the total QSO points multiplied by the sum of oblast and country multipliers.

11. General Log Submission Requirements 11.1. Logs are accepted in CABRILLO file format only.

11.2. Filename of your log should be yourcall.log or .cbr. Example: UA1AAA.log.

11.3. If a competitor claims two separate bands in the SOSB category (as per 3.1 ) these two bands should be clearly marked. Example: CATEGORY-BAND: 10m, 15m.

11.4. Russian stations will include their RDA in the LOCATION: field.

11.5. Web upload is the only method of log submission. Web upload of logs is available at: http://www.rdxc.org/asp/pages/wwwlog.asp.

11.6. All QSO times must be in UTC.

11.7. All sent and received exchanges must be clearly shown in the log.

11.8. The header of the electronic log must specify entry category and your full mailing address to receive the awards.

11.9. Multioperator logs (MOST and MO2T) must identify which transmitter made each QSO. For MOST entries RUN =0, MULT =1. For MO2T entries RUN1 = 0, RUN2 = 1. Alternative identifcation is not allowed. The logs without such identification will be reclassified to Check Log.

11.10. Logs aiming for the top 3 position in any contest category (excluding SWL entry) must indicate the frequency of every QSO made (using transceiver CAT) with a minimum resolution of 1 kHz.

11.11 Any QSO marked with the key X-QSO: will be ignored in your log and credit will be given to the other station.

12. Log Submission Deadline 12.1. Logs must be submitted to the contest sponsors within 14 days after the end of the contest (until 23:59 UTC on 04.04.2021).

12.2. Receipt of the log is confirmed on the “Logs received” page on RDXC Website.

12.3. Logs submitted after the deadline may be listed in the results, but are not eligible for awards.

13. Awards 13.1. pecial plaques for continental winners in the SOAB-MIX and SOAB-MIX-LP. For the complete list of sponsored plaques please visit http://www.rdxc.org/asp/pages/trophy.asp.

13.2. Every participant from Russia will receive a souvenir subject the terms below:

All-band entries confirmed at least confirmed 1,000 QSOs,

Single-band entries confimed at least confirmed 500 QSOs,

MIX-QRP entry confirmed at least confirmed 250 QSOs.

13.3. European participants will receive a souvenir for at least 750 confirmed QSOs with the Russian stations.

13.4. Non-European participants will receive a souvenir for at least 250 confirmed QSOs with the Russian stations.

13.5. All participants who have submitted the log will receive PDF participation certificates.

14. Contest-Related Information 14.1. Every participant who sends his electronic log will receive personal UBN-list with his claimed/confirmed results separately by bands/modes and QSO list, containing his errors and errors of worked stations. Confirmed Oblasts list for “Russia” award will be sent separately.

14.2. Russian Disctricts Award (RDA). All confirmed QSOs with the Russian stations will be atomatically accepted by the RDA without paper QSLs.

14.3. Any RDXC related questions should be sent to e-mail [email protected].

15. Judging The Russian DX Contest Committee is responsible for checking and adjudicating the contest entries which is done electronically. Participants are requested to follow the rules and best amateur radio practices. Violation of the rules of the contest or unsportsmanlike conduct may lead to disciplinary action by the Committee in its sole discretion.

16. Penalties Penalties are worth two times the QSO point value for the contact.

16.1. Penalty is appllied if:

incorrectly logged calls (Bad Call);

incorrectly logged exchange numbers;

16.2. QSO neither counted nor penalized for the following:

QSO time difference of more than 3 minutes (except systematic computer errors);

QSO bands or modes difference (except systematic computer errors);

10 minute rule violation for MOST (as per 5.3.1 and 5.3.3 above);

Band change violation for MO2T (as per 5.4).

16.3. The log will be reclassified into Check Log in case of more than 50% score reduction after checking.

16.4. RDXC Contest Committee decisions are final.

RDXC Contest Committee invites all the radio amateurs from Russia and foreign countries to take part in 28 Russian DX Contest, which became one of the most popular contest in the world. http://www.rdxc.org/asp/pages/news.asp

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The post RUSSIAN DX CONTEST – 2021 appeared first on QRZ NOW - Ham Radio News.

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Marius, FM/OQ3R will be active from Martinique Island, IOTA NA - 107, 23 May - 5 June 2021.

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Marius, ON4RU hopes to be QRV from Martinique during May 23 to June 5, 2021. (QTH: FM5BH). Participation in the CQWPX CW contest as TO3F. Outside of contest active as FM/OQ3R on 160-10m, CW only. QSL via H/c.

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FM/OQ3R & TO3F – Martinique

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WA7BNM Contest Calendar - 0700Z-1100Z, Mar 21

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WA7BNM Contest Calendar - 2300Z, Mar 21 to 0100Z, Mar 22

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swldx · 3 years ago

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7155Khz (USB) 0509 2 JUN 2022 - EA3BOX - male (John) RS=34 calling CQ from 100km North of Barcelona, Spain. Worked: @0509z N5YW, Weldon, S. Mississippi, 600W, 270ft dipole. 250ft unterminated BoG antenna pointed E/W w/MFJ-1020C active antenna (used as a preamplifier/preselector), Etón e1XM. 1kW, Omni, bearing 55°. Received at Plymouth, MN, United States, ~7297km from transmitter at Barcelona, Spain. Local time: 0009.

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brisbaneantennaprofessionals01 · 3 years ago

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All You Need To Know About Wi-Fi Radio Antennas in Brisbane

In this digital era, the usage of the Internet has become an important aspect for both business and private environments. There are many computerised devices and all of them require additional devices to increase the workflow. Most of the devices run on Wi-Fi and there if the signal is not strong, complications are bound to come. Wi-Fi Radio Antennas in Brisbane are increasingly becoming the top choice for many individuals and business establishments.

What’s the solution?

To amplify the signal of Wi-Fi, there are certain things that need to be prioritised. The surrounding factors also need to be considered. When it comes to antennas, they are critical for (WLAN). Therefore, if you have Wi-Fi antennas in your home or office, consider choosing the right one that works for your purpose.

The functionality of Wi-Fi Antennas

When it comes to wireless devices, to communicate seamlessly, the devices use radio waves between each. The signals are actually electromagnetic waves that contain your information. Sometimes, high frequency cabling may be required. Wi-Fi antennas communicated with your devices by converting electromagnetic waves into electrical signals. The antennas that are responsible for receiving signals, process the information and then again send it back to other devices. This means the transmitting antennas convert the electrical signals for transmitting back to the devices.

Types of Wi-Fi Antennas

Basically, there are two types of Wi-Fi Antennas. These are: directional and omnidirectional.

Directional Wi-Fi Antennas

Parabolic Grid Antenna – These antennas are known for having ultra-high gains. The width of the signal’s width is very narrow and therefore, these antennas can send and receive signals between miles.

Panel Antennas – These are strong antennas that are used for receiving and transmitting signals between long distances. They can be connected to a router or USB Wi-Fi adapter for receiving data.

Mini Panel Antennas – These are low profile antennas and are used for transmitting radio signals to and from a particular location. These are mainly used for strengthening indoor Wi-Fi signals.

Yagi Antennas – This is a very popular type. Yagi antennas look like arrows and they need to be pointed in the direction where the signals should be sent or received.

Omnidirectional Wi-Fi Antennas

Dipole Antennas or Rubber Duck Antennas – These are basically found on routers, Wi-Fi adapters, and access points.

Ceiling Dome Antennas – These are connected to an access point or a Wi-Fi router through coaxial cables. If using such antennas, make sure to prioritise the fiber optics for accurate signal transmission.

Outdoor Omni Antennas – These antennas are used for improving outdoor Wi-Fi signals. To improve the wireless connection, they are connected to access points and routers.

Getting to know about these antennas and associated cables can be sometimes confusing. Therefore, it is suggested that you hire professionals who provide Brisbane Antenna services. They are equipped to handle all types of requirements including TV points, MATV System for commercial builders, setting up Wi-Fi connections and many. They can also help you choose the right cables and antennas based on your needs.

Tap on the link to visit more website blogs: https://www.brisbaneantennaprofessionals.com.au/all-you-need-to-know-about-wi-fi-radio-antennas-in-brisbane/

#wifi redio antenna #fiber optics #high frequency cable

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rfantennaindia · 2 years ago

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brendabailey6 · 4 years ago

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The Slim Omni Antenna

Nowadays, slim omni antenna attract lots of attention by the general public, so let's get to understand what exactly is slim omni antenna actually. In a nutshell, this kind of antenna draws power from an external source by utilizing a tuned antenna, this enables it to receive and radiate without any interference from other electromagnetic fields. Sounds interesting? Then continue to read on as we discuss more about this amazing technology. The technology of slim omni antenna is actually quite simple and straight forward, it works on the same principles as other types of antenna such as antenna, omni band, etc., so it basically means the reception and transmission of radio signals are accomplished without any interference.

To better explain, an omnidirectional antenna distributed horizontally will have two main antennas which are vertically tuned, while slim omni antenna are also distributed horizontally. Basically, the electromagnetic fields of this kind of omni-antenna is in constant phase, no matter if they are transmitted or received. For instance when a mobile phone user receives a call, their handsets set off the main lobe of the slim omni antenna, while the second main lobe receives the call. This enables them to receive the call regardless whether or not there is a signal in the main lobe.

Although the above seems very simple, you must understand that this method of operation is pretty complex. To begin with, an omni dipole antenna is required, this is because such an antenna can only perform well in one specific frequency. It will only work in that one frequency, hence the name slim omni antennas, it only transmits and receives signals in a single frequency. These kinds of omni-dipoles are manufactured and used in communications systems. On the other hand, a dipole antenna is usually made up of several smaller antennas, in some cases even more than 10 antennas.

A dipole antenna has the ability to receive and transmit signals in only a single frequency, thereby enabling them to cover a wide area in a narrow span of time. The most common such device is the omni-dipole antenna, which is usually installed on towers or in areas where the receiving bandwidth is more limited. However, they can also be installed underground. In some cases, a thin film transceiver is used for omni-dipoles, which means that the main transmitter and receiver of the transceiver are placed far apart, making them difficult to locate. This also results in the possibility of losing some of the signals that are transmitted from the receivers.

Besides being used in telecommunications, the omni-antenna is also widely used for various other purposes. For instance they can be installed on top of cars. This is done to increase their receiving radii, thus allowing cars to communicate faster and more efficiently with other cars on the road. Another application of an omni-antenna is to be attached to telephone masts. The advantage of this over other forms of mast-mounted antennas is that it eliminates the need for a ground conductor. They are also suitable for installation on ships, airports, power lines and other sites where a high signal quality is a must.

However, the ones are not without their disadvantages. For one, they are much heavier and bulkier than most other forms of antennas. They are also less flexible and less resistant to environmental disturbances, such as wind and noise. This means that they should be installed carefully, using a special mounting gear.

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ct-rfantennas · 4 years ago

Video

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Indoor-outdoor Omnidirectional 2G 3G 4G LTE 5G NR Antenna Omni Dipole Ru...

#2g 3g 4g 5g #2g #3g #4g #5g #4g lte #5g nr #omni dipole antenna #indoor #outdoor #antenna

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antennaexperts · 2 years ago

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Military Multi Band Antenna is suitable for mounting the vehicle using a standard NATO 4 hole pattern. Multi-Band Coaxial Dipole Antenna is a rugged all-weather model uses high-class aluminum alloy and does not require any adjustments. The compact size of Omni-directional Multi Band Antenna manufactured by Antenna Experts is highly suitable for receiving, transmitting, and jamming applications without having the requirement of multiple antenna.

#Multi Band Omni Coaxial Dipole Antenna #Multi Band Log Periodic Antenna #Multi Band Omni directional Antenna #Military Multi Band Antenna Manufacturer #Military Multi Band Antenna #Multi Band Antenna

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mangowall · 4 years ago

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Specifications: 1. Frequnecy range: 2400MHz – 2500MHz2. Gain: 5-6dBi3. Impedance: 50 ohm4. Total length: 195mm (foldable antenna)5. Gain direction: omni6. Joint way: SMA internal hole7. Gain ...

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certainheartrunaway · 4 years ago

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Current Ham Radio News

Registration is now open for the 2021 HamSCI Workshop, Friday and Saturday, March 19 – 20. The theme of this year’s workshop is midlatitude ionospheric science. The University of Scranton will serve as host for the Zoom virtual event, sponsored by the National Science Foundation (NSF). The program will include guest speakers, poster presentations, and demonstrations.

The workshop will also serve as a team meeting for the HamSCI Personal Space Weather Station project, funded by an NSF grant to University of Scranton physics and electrical engineering professor Nathaniel Frissell, W2NAF. The project seeks to harness the power of an amateur radio network to better understand and measure the effects of weather in the upper levels of Earth’s atmosphere.

The workshop’s keynote address on the “History of Radio” will be given by Elizabeth Bruton, curator of technology and engineering at the Science Museum of London. She will discuss the history, science, technology, and licensing of radio amateur communities from the early 1900s to the present, exploring how individuals and communities contributed to “citizen science” long before the term entered popular usage in the 1990s. Bruton has been a non-licensed member of Oxford and District Amateur Radio Society since 2014 and has served as the society’s web manager since 2015.

J. Michael Ruohoniemi, a professor of electrical and computer engineering at Virginia Tech and principal investigator of the Virginia Tech SuperDARN Initiative, will review the physics of the midlatitude ionosphere and discuss ways in which the amateur radio community can contribute to advancing scientific understanding and technical capabilities.

Joe Dzekevich, K1YOW, will present “Amateur Radio Observations and The Science of Midlatitude Sporadic E.”

The event will also include virtual oral presentations by researchers from NASA Goddard Space Flight Center, MIT Haystack Observatory, the University of Oslo, the University of Bath, Case Western Reserve University, Dartmouth College, the University of Alabama, Clemson University, the New Jersey Institute of Technology, and The University of Scranton, among others.

University of Scranton students Veronica Romanek, KD2UHN; Cuong Nguyen; and M. Shaaf Sarwar, KC3PVF, are among the iPoster presenters.

Participation is free. The 2021 HamSCI Workshop is supported by the National Science Foundation and The University of Scranton. — University of Scranton news release

source:ARRL

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Omni-Directional – Circularly (Mixed) Polarized Antenna for 144 MHz / VHF / 2 Meters.

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Six-Band HF Center-Loaded Off-Center-Fed Dipole by ON4AA

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SOTABeams Features Fully adjustable audio band-pass filtering instantly adjustable for voice, data and CW (b/w 50 Hz to 5 kHz) VIDEO State-of-the-art... Read more

“Generators” is the topic of the new (June 22) episode of the “ARRL The Doctor is In” podcast.

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Video DL1FY CQ WW DX CW Contest 2021.

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Download the latest FREE DX-World Weekly Bulletin compiled by Bjorn, ON9CFG. Any changes or corrections, please drop an email to Bjorn.

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This activity is still very uncertain due to many Covid restrictions, however Janusz SP9FIH (ex-VK9NK) is planning to QRV from Saint Martin as TO1K during March 22 to April 5, 2021. Webpage.

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WA7BNM Contest Calendar - 0030Z-0230Z, Mar 18

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Ravi, YD7RV informs DX-World of the following IOTA OC-268 activity. 12/03 – Team underway to the Laut Kecil Islands OC-268. 13/03 – Operation in Marabatua Islands; Moresses Islands, mode: SSB, FT8. 14/03 – Operation in Payongpayongan, mode: SSB, FT8. 15/03 – Special call From Denawang Islands (Denawan National Park), turtle conservation and breeding place. QSL […]

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This idea came from Eli, N6PF and we think it’s good. Who remembers their first ever DX contact or first ever DX station heard (as SWL). How elated were you to contact a station on the other side of the world using a simple wire antenna? To start off – with the hope others reply […]

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ARRL -

ARRL will have two exhibits at the the QSO Today Ham Expo. One will offer opportunities to meet ARRL Lab engineers, who will answer questions and share tips on an array of topics. ARRL CEO David Minster, NA2AA, will deliver the Expo’s keynote address at 2000 UTC on Saturday, March 13.

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The full results of the 2020 ARRL November CW Sweepstakes have been published on the ARRL Contests web page. The full results article, a searchable database of all scores, line scores, certificates and Log Checking Reports are available there.

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ARRL -

Tad Cook, K7RA, Seattle, reports: Although solar activity remains low, in recent days, as a sunspot rotates to the west off the visible solar disc a new one emerges in the east. Sunspot group 2807 recently moved over the sun’s western horizon, but on March 9 new sunspot group 2808 moved across the eastern horizon, and a newer group (2809) has now emerged just south of the center of the solar di...

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xiaoquebanxiaoqueban · 4 years ago

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Chapter 6 wire antenna microwave technology and antenna 2nd Edition courseware ppt page 82

*6.4.3 log periodic antenna 1. The number of structural oscillators of log periodic antenna is n; the feed point of antenna is connected at one end of short dipole; the dipole is cross connected by parallel double lines with characteristic impedance, which is called assembly line. Is the included angle of the envelope at the end of the oscillator, which is called the internal angle of LPDA. , and are the distance from the oscillator to the vertex, the distance between adjacent oscillators and the length of one arm of the oscillator. Chapter 6 line antenna figure 6-4-8 outline of LPDA 6-4-9 structure size and feed of LPDA * 6.2.3 uniform linear array (3) phase scanning linear array if the antenna array does not rotate, only With the change of time according to a certain law, the maximum radiation direction and the whole pattern can move back and forth in a certain airspace, that is to say, the pattern scanning can be realized. Chapter 6 line antenna figure 6-2-11 schematic diagram of phase scanning array and frequency scanning array a) phase scanning array B) frequency scanning array * 6.2.3 uniform linear array Chapter 6 line antenna figure 6-2-12 E-plane pattern of phase scanning array (,) a) θ M = 90 ° b) θ M = 75 ° C) θ M = 30 ° d)3. The antenna pattern will have many large lobes with the same maximum value in the corresponding direction when the spacing between the grid lobes and the selection elements of the spacing is too large. Generally, the corresponding large lobe is called the main lobe, which is equal to other values, and the corresponding large lobe is called grating lobe. The condition of eliminating the maximum value of the grating lobe the condition of eliminating the whole grating lobe Chapter 6 the directivity analysis of the line antenna * 6.2.4 uniform linear array 1. Zero radiation direction and main lobe width (1) zero radiation direction (2) zero power width of main lobe (3) half power width of main lobe (main lobe width) Chapter 6 directivity analysis of line antenna * 6.2.4 uniform linear array (4) The zero radiation direction and the main lobe width of several long uniform linear arrays (). Sidelobe level (1) sidelobe maximum direction (2) sidelobe maximum value (3) sidelobe level First sidelobe level Chapter 6 line antenna DB*(2. The analysis of the linear distribution of the linear distribution of the equal amplitude distribution of the triangular array; 2 Triangle distribution; (c) binomial distribution; (d) inverted triangle distribution * 6.2.5 unequal Ultra-thin Omni Antenna manufacturers</a> amplitude and equal spacing side firing linear array Chapter 6 line antenna (2) binomial distribution (3) inverted triangle distribution (1) triangular distribution * 6.2.5 unequal amplitude and equal spacing side firing linear array (4) comparison As far as the feed current is concerned, the decreasing rate of binomial distribution from the center to the outside is greater than that of triangle distribution, the decline rate of equal amplitude distribution is zero, and that of inverted triangle distribution is increasing (or negative). As far as the side lobe level is concerned, the binomial distribution is the lowest (without side lobe), and increases in the order of triangle distribution, equal amplitude distribution and inverted triangle distribution. It can be seen that the lower the side lobe rate is, the more the current >lpda antenna manufacturer</a> decreases from the center to the outside. Chapter 6 line antenna * 6.2.5 unequal amplitude and equal spacing linear array Chapter 6 line antenna figure 6-2-14 5-element side fire array (d = λ / 2) pattern (a) equal amplitude distribution (b）2. Dolph Chebyshev distribution is a kind of distribution which has the best compromise between the side lobe level and the main lobe width. Among all the symmetrical decreasing feed current distribution arrays, under a given sidelobe level (or main lobe width), its main lobe width is the narrowest (or the sidelobe level is the lowest), and it has the characteristics of equal sidelobe. Therefore, it is called the optimal sidelobe array. In engineering, many kinds of quasi optimal edge firing arrays have been proposed, such as Taylor distribution matrix, Bayliss distribution matrix and so on, which have almost become the industrial standard. Chapter 6 wire antenna * 6.3 influence of ground plane on antenna performance 6.3.1 mirror image method 1. General concept The image method is to replace the boundary of the field problem with some imaginary charges and currents outside the studied region. If the electromagnetic fields generated by these charges and currents together with the original charges and currents in the studied area meet the boundary conditions of the original problem, then the electromagnetic field is the field solution to be solved. In Chapter 6, line antenna * 6.3.1 mirror image method 2. Mirror image of the basic electric oscillator to the infinite ideal conductor plane 3. The expression of the mirror image method, after replacing the infinite ideal conductor plane with the mirror image of the basic electric oscillator, the field solution of the original problem is equal to the field generated by the original oscillator and its mirror imageIn other words,

is the superposition of

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