Category Archives: Ham Radio

Small Unidirectional Loop Antenna (SULA) Part 3: Questions & Answers

Many thanks to SWLing Post contributor extraordinaire, 13dka, who brings us Part Two of a three part series about the new SULA homebrew antenna project. This first article describes this affordable antenna and demonstrates its unique reception properties. The second article focuses on construction notes. This third and final article will essentially be a Q&A about the SULA antenna.

This wideband unidirectional antenna is an outstanding and innovative development for the portable DXer. I love the fact that it came to fruition via a collaboration between Grayhat and 13dka: two amazing gents and radio ambassadors on our SWLing.net discussion board and here on the SWLing Post. So many thanks to both of them!

Please enjoy and share Part 3:

Part 3: SULA Q&A

by 13dka

Q: Where can I ask questions, discuss all aspects of the the SULA or collaborate in its further development?

A: There is a thread dedicated to the SULA in the new SWLing.com message board: https://swling.net/viewtopic.php?t=55

Q: Since the antenna is “lossy”, what’s the point of having a “beam”?

A: The answer is once again “SNR”: First off, remember that the LNA is there to make up for most of the losses. Secondly, this is all about the noise pickup, 20dB less gain/more losses outside the main lobe means also a reduction of atmospheric/cosmic/whatnot QRN and of course everything manmade from all these sides. The wide horizontal lobe is more or less one hemisphere horizontally, but the flat-ish vertical pattern makes that only a slice of it. In other words, there will be less QRN and QRM pickup from the back and the top. The idea is that the SNR will ideally increase more than the preamp’s noise figure will cost and it often sounds like this is what actually happens. Of course it’s also nice that you can turn an unwanted signal down using the more or less pronounced notch in the backside pattern up to 21 MHz – also very helpful for direction finding.

Q: Do I need a rotor?

A: It depends. If you are one of the lucky few still having a low-QRM-environment at home and you want to put it in the backyard, you really may want to be able to turn it remotely. If you’re using it portable you can simply rotate the mast manually. If you have local QRM or can’t mount it very far away from your or other houses, you may want to rotate the back of the antenna towards that source, leave it at that position forever and enjoy what’s coming in on the pretty wide main lobe of the antenna. The horizontal lobe covers more or less half of the horizon, depending on your stations of interest and location you could get away with never turning the antenna at all.

Q: Is it better than the XYZ loop?

A: Hey, that’s exactly what I wanted to ask you! 🙂 Even though the SULA is very similar in appearance and performance to a good SML working in ideal (ground conductivity) conditions, the SULA is a pretty different animal with a different behavior: Regular small loops, besides being bidirectional, can lose quite a bit of their low angle sensitivity over “poor” ground while the SULA is supposed to be retaining its properties better over any type of ground. Also, while many SMLs are tuned for VLF through the lower portion of the shortwave, the SULA complements those with quite uniform (good) properties up to 30 MHz and beyond.

Q: I have an end-fed random wire or dipole strung up from the house to a tree etc. – can the SULA beat that?

A: That’s quite possible. To get low takeoff angles from horizontal wire antennas you need to string them up at least 1/2 wavelength high, that’s 20m/66ft on 40/41m, 10m/33ft on 20m and so on. If you can’t do that, the SULA may be your ticket to listen farther beyond the horizon. Also, wire antennas are often strung up to match space restrictions or avoid QRM vectors and that way you may end up with some directionality in directions you don’t want, or no directionality at all when the wire is too low. Another noteworthy point is the ground: For most horizontal antennas, better ground means a considerable higher takeoff angle so the dipole needs even more height for low angles. The SULA’s takeoff angle benefits a little from the better ground and only gets a little worse over poor ground.

Q: Do I really need an LNA?

A: I hope so? Of course it depends… if you are going to try this antenna in a very noisy environment, the LNA may have little to no benefit. The noise is limiting your “radio horizon” to very loud signals anyway and for those you may not need an LNA, ever. On the other hand, the antenna is very lossy and in a quiet environment where noise is not an issue at all, weak signals may drop below the sensitivity threshold of your receiver without the LNA. The less noise you have, the more you’ll be able to benefit from an LNA. You will also need one when your radio isn’t all that sensitive, similar to the requirements to run a YouLoop. Andrew kept the loop impedance as constant as possible in order to allow any low impedance coax preamp to work behind the Balun. Any LNA with 20dB of gain should do, as per usual, better stuff may bring better results.

Among the sparse offers for decent shortwave LNAs, the NooElec LANA HF seems to be the only decent LNA sold via Amazon. It’s comparatively low-cost and unlike the other offers on Amazon, ready to be powered via Bias-T or even via Micro-USB and therefore happy with 5V. Since I also had the balun from the same company I could simply connect that all with a couple of these cute little SMA plumbing bits and it worked. The downside is its unknown but perceivably low resilience against intermodulation (low 3rd-order intercept point), this is usually not a problem with such a small loop but it can be in the presence of nearby transmitters.

If you do have nearby transmitters and don’t mind sourcing an LNA from Europe, Andrew recently pointed me to preamps from here. They offer a moderately priced preamp with a 2N5109 transistor (based on the W7IUV design) for a high IP3 value and low noise, which is also available in PCB-only and fully assembled versions including a compartment. They also offer Bias-T boxes.

Q: What is special/different about this antenna? There are already very similar designs!

A: It’s supposed to be simpler and more compact/portable, and it seems to deliver more consistent results over the entire coverage range in different usage environments than similar designs. The SULA was designed to be made with things that are particularly easy to obtain, or which were already obtained — many of us SWLs have some of that Nooelec stuff in our drawer anyway, even when (or because) we’re not habitual antenna builders and balun winders. Now making a better balun and buying a better preamp is not hard and could even bring better results but the point is that you don’t have to. In summary, this is not meant to be a miracle antenna, just number of compromises re-arranged to create a particularly uncomplicated, small, unidirectional loop antenna that aims for DX, for apartment dwellers and DX nomads like me.

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Radio Waves: US Emergency Alert System Vulnerabilities, Tape Measure Antennas, Eight Year Old Chats with ISS, and Power of Prison Radio

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Radio Waves: Stories Making Waves in the World of Radio

Welcome to the SWLing Post’s Radio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!

“Huge flaw” threatens US emergency alert system, DHS researcher warns (ARS Technica)

Hackers can disrupt legit warnings or issue fake ones of their own.

The US Department of Homeland Security is warning of vulnerabilities in the nation’s emergency broadcast network that makes it possible for hackers to issue bogus warnings over radio and TV stations.

“We recently became aware of certain vulnerabilities in EAS encoder/decoder devices that, if not updated to the most recent software versions, could allow an actor to issue EAS alerts over the host infrastructure (TV, radio, cable network),” the DHS’s Federal Emergency Management Agency (FEMA) warned. “This exploit was successfully demonstrated by Ken Pyle, a security researcher at CYBIR.com, and may be presented as a proof of concept at the upcoming DEFCON 2022 conference in Las Vegas, August 11-14.”

Pyle told reporters at CNN and Bleeping Computer that the vulnerabilities reside in the Monroe Electronics R189 One-Net DASDEC EAS, an emergency alert system encoder and decoder. TV and radio stations use the equipment to transmit emergency alerts. The researcher told Bleeping Computer that “multiple vulnerabilities and issues (confirmed by other researchers) haven’t been patched for several years and snowballed into a huge flaw.”

“When asked what can be done after successful exploitation, Pyle said: ‘I can easily obtain access to the credentials, certs, devices, exploit the web server, send fake alerts via crafts message, have them valid / pre-empting signals at will. I can also lock legitimate users out when I do, neutralizing or disabling a response,’” Bleeping Computer added. [Continue reading…]

Just how good is a tape measure antenna anyway? (Hackaday)

Amateur radio operators have played a longstanding game of “Will It Antenna?” If there’s something even marginally conductive and remotely resonant, a ham has probably tried to make an antenna out of it. Some of these expedient antennas actually turn out to be surprisingly effective, but as we can see from this in-depth analysis of the characteristics of tape measure antennas, a lot of that is probably down to luck.

At first glance, tape measure antennas seem to have a lot going for them (just for clarification, most tape measure antennas use only the spring steel blade of a tape measure, not the case or retraction mechanism — although we have seen that done.) Tape measures can be rolled up or folded down for storage, and they’ll spring back out when released to form a stiff, mostly self-supporting structure.

But [fvfilippetti] suspected that tape measures might have some electrical drawbacks, thanks to the skin effect. That’s the tendency for current to flow on the outside of a conductor, which at lower frequencies on conductors with a round cross-section turns out to be not a huge problem. [Continue reading on Hackaday…]

Broadstairs eight-year-old to feature on NASA website after radio chat with ISS astronaut (The Isle of Thanet News)

A Broadstairs eight-year-old has chatted with an astronaut aboard the International Space Station and a recording of the conversation will feature on the NASA website.

Isabella Payne spoke to Astronaut Kjell Lindgren as the ISS flew overhead last week.

The youngster was with dad Matthew who is a license holding amateur radio enthusiast and tutor. He and Isabella are both members of Hilderstone Radio Society.

Matthew said: “Isabella has been a member of the radio club ever since she was born and has been playing with the radio since she was six. Because I have the full licence she can sit on my knee and use the radio to speak to people as long as I am controlling it. Everyone at the club can do that. She has been involved in a few radio events, Children On The Air events, and will hopefully go for her own licence soon. [Click here to read the full article and view the photos.]

The power of prison radio in giving voice to the voiceless around the world (ABC)

“I plan my life by the radio these days, my contact with the outside world in a sense…”

The first ever international prison radio conference has just been held in Norway, bringing together representatives of prison radio shows from 19 countries, including Australia, where Indigenous people continue to be grossly over-represented in prison populations.

Prison radio shows, wherever they are in the world, all work to give voice to the voiceless and empower people by enabling them to tell their own stories.

Click here to listen to the podcast episode.

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Radio Waves: Radio Liberty Journalist Bugged, Invisible Battle, RNZ Shortwave After Tonga Eruption, Closing Analog FM in Spain to Save Energy, and Keeping Morse Code Alive

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Radio Waves: Stories Making Waves in the World of Radio

Welcome to the SWLing Post’s Radio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!

Journalist Vitaly Portnikov was found to be “eavesdropped” at his home in Lviv, – Knyazhytskyi (Espeso)

Note this article has been translated in English. Original in Ukrainian found here.

The police promptly responded to the call, but the SBU for some reason delays its response to illegal actions People’s deputy Mykola Knyazhytskyi announced this on Facebook .

“In Lviv, journalist Vitaly Portnikov, who hosts programs on Espresso and Radio Svoboda, found a eavesdropping device at home. It is a voice recorder with the ability to record for a long time. The police were called. They arrived quickly. The SBU was called. They are not going. As a member of the Verkhovna Rada, I ask the SBU to come immediately and disrupt case. We don’t know who installed this device and for what purpose: our services, foreign services or criminality,” the politician said.

Image via Espreso

Vitaly Portnikov commented on the incident for “Espresso”:

“Today, while cleaning the apartment I lived in at the end of February, when the war started, I found a recording device under the bed. The device had an inventory number. I informed the law enforcement authorities about my discovery so that they could investigate this incident.”

The journalist added that he hoped for a high-quality investigation and clarification of all the circumstances of the case:

“After my statement, the investigators of the SBU of the Lviv region conducted an inspection of the premises and seized a device that is a device for listening and recording information. I hope that the relevant structures will conduct an examination and find out by whom and why this device was placed in my apartment.”

Vitaly Portnikov is a well-known Ukrainian journalist, publicist and political commentator. Cooperates with Radio Svoboda and Espresso. On the Espresso TV channel, he creates the programs “Political Club of Vitaly Portnikov” and “Saturday Political Club”. [Click here to read the full article at Espreso.]

The Invisible Battle of the Cold War Airwaves (Bureau of Lost Culture)

This Episode explore three stories of cold war era radio in the USSR: Soviet Radio Jammers, the Russian ‘Woodpecker’ and the Soviet Radio Hooligans

[Click here to listen to the podcast via PodBean.]

We meet with Russian broadcaster Vladimir Raevsky to talk about radio jamming in cold war era Soviet Union.

As East and West super powers square up to each with nuclear weapons, a parallel invisible war is being fought in the airwaves. Continue reading →

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Dan shares a few photos from the Berryville Hamfest

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Many thanks to SWLing Post contributor, Dan Robinson, who shares the following photos from the Berryville Hamfest.

Dan notes that the resolution is not great in these photos, but I believe we can still see enough detail to know that this hamfest had many vintage treasures:

Thank you once again for sharing these, Dan!

Click here to see images from previous Berryville Hamfests.

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Radio Waves: Brooklyn Pirate Radio Interview, Emergency Radio Evolution, SOTA Hams Prevent Forest Fire, and Morse Code Documentary

Radio Waves: Stories Making Waves in the World of Radio

Welcome to the SWLing Post’s Radio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!

Interview about Brooklyn pirate radio (Irish Pirate Radio Audio Archive)

Although Irish pirate radio is our main interest, today we explore the lively pirate scene in the Brooklyn area of New York City. The Brooklyn Pirate Radio Sound Map is a fascinating project established by radio producer and audio archivist David Goren and provides interactive maps and historical and contemporary recordings of the many unlicensed stations in Brooklyn.

This is a longer version of an interview by John Walsh with David Goren first featured in Wireless, a series about radio, audio and media on Flirt FM in Galway. It covers the history of pirate radio in Brooklyn and New York generally, attempts to crack down on the unlicensed stations, the role of low-powered FM, the background to the Brooklyn Pirate Radio Sound Map itself and plans for the future. Many thanks to David for taking the time to explain this fantastic project for us. [Read the full article and listen to the interview on the Irish Pirate Radio Audio Archive…]

The Evolution of the Emergency Radio (Radio World)

From AM-only portables to multi-function machines

With the advent of the 9V battery-powered transistor radio in the 1950s, the “Emergency Radio” was born.

Unlike vacuum tube receivers with heavy batteries or unpowered crystal radios, these handheld AM portables were small and simple enough to keep in a drawer. They could then be retrieved whenever man-made or natural disasters knocked out the power, providing listeners with lifeline connections to news, weather and relief information. Continue reading →

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A most unusual QSL . . . card?

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By Jock Elliott, KB2GOM

Okay, I realize this is ham related, but I thought it was fun, and I hope you do too.

On a quiet Saturday morning in May, the “Big Gun” Motorola 1250 (which is used for running the Commuter Assistance Net) is quietly scanning through half a dozen frequencies.

The scanning stops on the 147.330 repeater, and a computer voice announces: “Echolink activated.”

Huh, that’s unusual, I think.

According to echolink.org, here’s the scoop on EchoLink:

EchoLink® software allows licensed Amateur Radio stations to communicate with one another over the Internet, using streaming-audio technology. The program allows worldwide connections to be made between stations, or from computer to station, greatly enhancing Amateur Radio’s communications capabilities. There are more than 350,000 validated users worldwide — in 159 of the world’s 193 nations — with about 6,000 online at any given time.

A few seconds later, a male voice with a distinct British accent drops a call on the repeater: “GB2022ER.”

What?!! A Great Britain call sign with multiple numbers in the middle? What’s going on?

I reply: KB2GOM.

Mark, the British ham, tells me he is running a special events station with a special call sign to celebrate the Queen’s Jubilee. He tells me I am the very first contact for the special events station. I tell him that he is my very first Echolink contact.

We chat for a bit, exchange good wishes and sign off.

A bit later, I look him up on QRZ and send Mark an email. Since I am his first contact for the special events station, is there a QSL card available? He replies that he will see what he can do.

A few weeks later, an envelope arrives with this coaster inside:

For a moment, I felt like James Bond:

Also inside were these postcards:

In all, it made me smile.

Bottom line – moral of the story, if you will – you never know what’s going to happen on the radio.

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W9IMS: From the Speedway to Your Wall

From the Speedway to Your Wall: Taking the W9IMS Checkered Flag

By Brian D. Smith, W9IND

The Checkered Flag is in sight – for hams and SWLs who’ve completed two-thirds of the chase for the annual W9IMS certificate. And for those who haven’t, there’s still a special QSL card awaiting all who snare the final contact during the coming week.

As its initials imply, W9IMS stages special events in honor of the Indianapolis Motor Speedway’s three major races. The third and final operation of 2022 – commemorating the NASCAR 200 at the Brickyard – will activate between the hours of midnight Indy time (0400 UTC) Monday, July 25, and midnight Sunday, July 31 (0400 UTC Tuesday, August 1).

Earning the 2022 Checkered Flag Award depends on working or tuning in each of the three special events. Since the first two races (the IndyCar Grand Prix and the Indianapolis 500) ran in May, it’s obviously too late to claim the clean sweep.

However, W9IMS also issues collectible QSL cards for the three individual races, so there’s still time to get a piece of the action.

Where to start? Well, W9IMS favors 20 and 40 meters, sometimes adding 80 meters later in the week (not to mention 2 meters on Race Day for locals and fans in the stands at the Speedway). Preferred frequencies are 14.245 and 7.245 SSB, plus or minus QRM.

But rather than spin the dial, try scanning the following tips for finding W9IMS on the air:

Check DX Summit (www.dxsummit.fi) for spots listing the current frequency or frequencies of W9IMS, if any. By typing “W9IMS” in the search box at upper right, you can customize it to show reports for only Indianapolis Motor Speedway special events. Naturally, you’ll be interested in only the ones from July 2022.
Go to the W9IMS web page (www.w9ims.org) and look for the heading, “2022 Operating Schedule.” Click on the NASCAR 200 link, which opens into a weeklong schedule listing individual operators and their reserved time slots. Your odds of catching W9IMS on the air improve significantly during these hours.
Prime operating time on weeknights is 6 to 10 p.m. Indy time (2200-0200 UTC). However, W9IMS can appear anytime, even on two bands at once, between 0400 Monday, July 25, and 0400 Sunday, July 31.
Remember that the published schedule can be shortened by adverse circumstances, such as noisy band conditions, local thunderstorms or a lack of calling stations. Don’t wait till the final hour to chase W9IMS!
Operators often get on the air at unscheduled times. That’s why DX Summit is your best bet for locating W9IMS’s current spot(s).
If you plan on going for the 2023 Checkered Flag Award, remember that the three required W9IMS special event QSOs (or reception reports) must come from each of the year’s three races – the Grand Prix, the 500 and the Brickyard. Making three contacts during the coming week still earns you the colorful Brickyard QSL card, but no extra credits toward the 2022 certificate.

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