Tag Archives: DXing

Dan asks: “What is your longest DX?”

Many thanks to SWLing Post contributor, Dan Greenall, who writes:

What is your longest DX (from transmitter to receiver)?

Assuming we are limiting the discussion to planet Earth, Perth, Australia would be represent one of the farthest land based locations to hear at 18145 km or 11275 miles as the crow flies from my receiving post in southern Ontario, Canada.

That would mean the ABC outlet that I received on 9610 kHz in the early 1970’s is the winner for me. Not far behind, however, would be tiny Amsterdam Island (part of the TAAF, Terres Australes et Antarctiques Francaises) in the Indian Ocean at 18031 km or 11204 miles. I was able to log marine radio FJY4 on 8690 kHz CW on a number of occasions and even managed to extract a PFC QSL direct from the station in 1973.

There are a number of distance calculators for this on the internet, such as Free Map Tools at
https://www.freemaptools.com/how-far-is-it-between.htm

Of course, the longest DX may not necessarily be the best. CKZN running 300 watts on 6160 kHz from St. John’s, Newfoundland from right here in Canada was harder to hear than the ABC in Perth, Australia!

Who can top this distance? What is your longest DX? Please comment!

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Guest Post: 10 Meter Beacon DXing

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Many thanks to SWLing Post contributor, Walter Salmaniw, who shares the following guest post:

10 Meter Beacon DXing

by Walter Salmaniw, Masset, BC

My hobby of radio listening has evolved over the years. Beginning with crystal radios as a child in the 60s, I’ve migrated through SWLing with numerous rigs including the kings of valve technology, like the Collins R390A and Racal RA17, and then on to high end mil-spec solid state rigs: Racals, Harris, Ten-Tec, and my all-time favourite, the Rockwell-Collins HF-2050 receiver. Unfortunately, broadcast band stations, especially transmitting to North America, have dwindled over the years, and my favourite Pacific stations also disappeared: 120 and 90 meter Indonesians, the 60 meter AIR network, and the numerous PNG stations. Well, what’s one to do?

About 10 years ago, I switched over to MW DXing, and especially trans-Pacific and trans-Atlantic DX. My cottage near Masset, BC is the ideal location for such DXing, as I have an ocean beach location, the room for some great antennas, and very low noise in the area. This has produced some incredible DX, and I’ve been honoured with visits by some pretty eminent DXers, including Victor Goonetilleke from Sri Lanka, Mauno Ritola from Norway, Vlad Titarev from Ukraine, as well as our own experts in DXing from Victoria and the Pacific North-West of the US.

MW DXing is great, but that involves DXing primarily during the night time and early morning hours. What to do with the rest of the day? Well, with the rising sunspot counts and heading toward the peak of the next solar cycle, why not look at 10 meters? About 2 years ago, with a lot of help from the local DX geniuses, I was able to remote my set-up in Masset, and DX even when at home in Victoria, BC. 10 meters has consistently remained open almost every afternoon. Now, I’m not a ham, and at this point, have no interest in obtaining my ham license. However, I noted a lot of beacon activity on 10 meters.

I’ve dabbled in LW NDB DX, which can be a lot of fun. Why not do something similar on the higher frequencies? Not being a ham, I needed some help with decoding the beacons. Thankfully, one can often see the CW and it’s slow enough to read in many cases. Being a bit too lazy for that exercise, though, I’ve tried several software solutions to use with my KiwiSDR and Perseus SDR in Masset. Fldigi is probably best known, and works fairly well. Another program I use is MixW, which I’ve always liked for SSTV reception. Another is CW Decoder. None, however, get anywhere close to how well CW Skimmer works. It’s an awesome program, albeit a pricey one. I’m still in the test phase, but will likely go ahead and fork over the $75 to purchase this. It will even take control of my Perseus receiver and decode 192 kHz worth of spectrum. Wow!

Here’s an example of what the band looked like last weekend:

There happened to have been a world-wide CW DX competition, but nonetheless, there were literally hundreds of CW signals to be decoded! Now, for me, however, I was more interested in the Beacon region of 10 M which is roughly between 28150 and 28300 kHz. I’ve found CW Skimmer to be a perfect tool to decode the beacons. Not only is it very accurate, but one can also easily see the CW signal with the dahs and dits on the screen and a continual readout of the messages. Most of these beacons run 5 or 10 W, and all are run by amateurs. Where to find information about who they belong to? That’s easy as well. WI5V.net has a great 10 M beacon list at https://wi5v.net/beacon-list-table-version/ . That’s my go to, but I also have DL8WX.de’s beacon list on my laptop, giving even more information, like contact e-mails, etc. He’s found at: http://www.dl8wx.de/BAKE_KW.HTM

What type of antenna do I use? Well, none of mine are 10 M antennas at all. Most are, in fact, for DXing trans-oceanic MW DX! Still, they seem to work quite well. My go-to has been a DKAZ antenna aimed 290 degrees. Now, that’s 180 deg to where most of my Beacon activity comes from. How come? Well, Nick Hall-Patch, MW DXer extraordinaire, used his ENZEC antenna prediction program to see how the DKAZ works on 28 MHz, and sure enough, it’s opposite to MW DX. On the lower band, it’s best aimed 290 deg, but 180 deg opposite on 28 MHz! Who would have guessed that one? In any case, the next time I’m in Masset, I plan on putting up a simple vertical for 10 meters, seeing that solar max is still a year or two away, so there’s plenty of time for some fun DX!

Here’s what I’ve heard with a few afternoons of listening. My best catch has been Darwin, Australia!

28207 N4XRO 1924 CW 5 watt beacon heard with a bit of a buzzy signal best deciphered on my 110 deg DKAZ…. 17/Oct/2022 (Salmaniw, Masset, BC)

28236.5 W0KIZ 1933 CW Another well heard beacon this morning giving ID in CW along with location. Also very strong at 23:11 recheck. Almost a barn burner! Not bad for 5 watts! 17/Oct/2022 (Salmaniw, Masset, BC)

28244 WA6APQ 1934 CW Much stronger, and it shows with their 30 watts output, with slow CW giving callsign, then location. Very strong when rechecking at 23:05 UTC. Frequency is actually a little lower than listed. Actually measuring 28243.942 kHz. 17/Oct/2022 (Salmaniw, Masset, BC)

28287 WI6J 1949 CW Poor reception, but with same format giving ID and location. 17/Oct/2022 (Salmaniw, Masset, BC)

28250 K0HTF 2248 CW Fairly good copy of this beacon away from the coast now in Iowa. Only giving callsign/B. Tom ‘Doc’ Gruis

replyed to my email confirming he’s feeding 20 Watts from an Old President radio and feeding an AR-10 antenna. Thanks, Doc! 17/Oct/2022 (Salmaniw, Masset, BC)

28248.3 NJ5T 2258 CW A relatively difficult catch, but I decoded the J5 part of his call, as well as ‘dipole’. 17/Oct/2022 (Salmaniw, Masset, BC)

28215 KA9SZX 1954 CW Beacon quite well heard from Masset. Most of my 10 meter beacon loggings have been a more N/S axis, but this one is coming in nicely in our early afternoon. Callsign and power listed as 3 W, along with his email address. 5/Nov/2022 (Salmaniw, Masset, BC)

28218 AC0KC 2035 CW Despite being listed as on 28218.5, he’s actually on the even channel at fair level into Masset. Solar powered and only 3W, into a Bazooka antenna (what’s that?). Call sign repeated. 5/Nov/2022 (Salmaniw, Masset, BC)

28220 AA8HS 2123 CW Despite listed as 30 Hz higher, I’m hearing them on the even channel with repeated IDs. Fair level. Antenna listed is a vertical J-Pole. 5/Nov/2022 (Salmaniw, Masset, BC)

28230.3 W2MQO 2125 CW Strong reception with call sign as W2MQ0/B repeated twice, then tones, and cycle repeats. Into a Bazooka Antenna. 5/Nov/2022 (Salmaniw, Masset, BC)

28203 KG8C0 2132 CW Another strong beacon with call sign, and prolonged tone, and repeat. 5/Nov/2022 (Salmaniw, Masset, BC)

28203.5 K6LL 2134 CW Strong signal also from California, ID’ing as K6LLL/BCN, and giving location and QSL info. 5/Nov/2022 (Salmaniw, Masset, BC)

28193 VE4ARM 1827 CW Excellent reception of my first 10 meter Canadian Beacon. Run by the Austin, MD Amateur Radio Museum, as outlined in their beacon text. 6/Nov/2022 (Salmaniw, Masset, BC)

28284.8 N9TNY 2226 CW Another new one for me from Illinois. Not a particularly great afternoon, but nonetheless, a number of CW Beacons on 10 meters are visible/audible. Callsign is given, then PSE RST. Not sure what that means? Wiki tells me that this is like SIO or SINPO code. Stands for Readability-Signal Strength-Tone. Hmm. 28/Nov/2022 (Salmaniw, Masset, BC)

28297 NS9RC 2237 CW Another Illinois Beacon audible. This one is weak, but fiddling with the KiwiSDR AGC settings, makes for a much better decode (mostly raising the CW Threshold (marked Thresh CW in the AGC section). Near 100% correct decode now. Chicago is sent along with call sign. 28/Nov/2022 (Salmaniw, Masset, BC)

28287 WI6J 2240 CW Strong signal from this Californian, and heard before. VVV VI6J/B Bakersfield CA DM 5 28/Nov/2022 (Salmaniw, Masset, BC)

28254.5 K4JEE 2243 CW Good copy with VVV DE K4JEE/B K4JEE/B K4JEE/B LOUISVILLE, KY 28/Nov/2022 (Salmaniw, Masset, BC)

28236.5 W0KIZ 2300 CW Always one of the strongest beacons on 10 meters, and not disappointing this afternoon. VVV W0KIZ/B DENVER, COLORADO . 5 WATTS, So does he mean 5 or 0.5 Watts? Presumably 5 Watts. 28/Nov/2022 (Salmaniw, Masset, BC)

28206.5 KA7TXS/B 2303 CW Nice reception with VVV DE KA7TXS/B DM22 Listed in dl8wx.de website, but not the primary one I use (wi5v.net Beacon Website). 28/Nov/2022 (Salmaniw, Masset, BC)

28209 N5TIT/B 2315 CW Fair reception with VVV DE N5TIT/B EM1UPX, or something similar. 28/Nov/2022 (Salmaniw, Masset, BC)

28211.8 AC7GZ 2321 CW Good reception for only 3 W with VVV DE AC7GZ AC7GZ AC7GZ DM3BI. The latter is the ham grid square, near Mesa, AZ. 28/Nov/2022 (Salmaniw, Masset, BC)

28232.3 W7SWL 2323 CW I like the callsign! Fair reception with VV DE W7SWL TUCSON AZ DM42 The band is fading fast. Fascinating that the best antenna for 10 m Beacon reception today is my 290 deg DKAZ (and not the 110 deg DKAZ). Not sure why! 28/Nov/2022 (Salmaniw, Masset, BC)

28206.5 N4SO 2231 CW Very weak, but really picked up just now. DE N4SO/B repeated. A fine catch! 30/Nov/2022 (Salmaniw, Masset, BC)

28212.8 AC7GZ 2253 CW Very strong reception with VVV DE AC7GZ AC7GZ AC7GZ DM43BI 30/Nov/2022 (Salmaniw, Masset, BC)

28209.5 N2UHC 2300 CW Tough copy, but bits of STPAUL decoded. as well as N2UHC/B. 30/Nov/2022 (Salmaniw, Masset, BC)

28254.5 K4JEE 2308 CW Strong reception with ID and location. Deep fades, as well, though. 30/Nov/2022 (Salmaniw, Masset, BC)

28255.8 WI5V 2310 CW Fair reception with occasional good fade-ups with WI5V/B repeated. 30/Nov/2022 (Salmaniw, Masset, BC)

28175.5 VE3BKM 2034 CW Hearing an unlisted beacon. VE3BKM/BCN repeated, often at strong level. A new one for me! 5/Dec/2022 (Salmaniw, Masset, BC)

28168 VA3KAH 2040 CW I have no idea where this island is located, so had to look it up. Fair reception with VV DE VA3DAH/B It’s located to the north of Lake Simcoe in southern Ontario. 5/Dec/2022 (Salmaniw, Masset, BC)

28145 DL2WB 2048 CW A highly tentative logging. All I hear is the occasional tone for several seconds, then off. Nothing else listed on this frequency, so no idea! 5/Dec/2022 (Salmaniw, Masset, BC)

28203 KG8CO 2055 CW Very strong signal with repeated KG8CO/BT 5/Dec/2022 (Salmaniw, Masset, BC)

28203.5 K6LLL 2058 CW Weak reception with VVV K6LLL/BC Grid Square coordinates, and PSE QSL TNX DE K6LL/BCN. 5/Dec/2022 (Salmaniw, Masset, BC)

28206.3 KA7TXS 2100 CW Strong reception, although a bit of a congested part of the band making decodes a tad difficult. Not listed on my main source (WI5V Beacon website), but it is on the dl8wx.de website. 5/Dec/2022 (Salmaniw, Masset, BC)

28208 WD5GLO 2126 CW Fair copy with WD5GLO/B repeated 3 times and OK OK 5/Dec/2022 (Salmaniw, Masset, BC)

28209.1 N5TIT 2130 CW Poor reception this afternoon, but making out the call-sign. VVV DE N5TIT/B. 100 Hz higher than listed. 5/Dec/2022 (Salmaniw, Masset, BC)

28209.5 N2UHC 2133 CW Poor reception, but seeing his callsign. Fades up to quite good at times. N2UHC/B EM27JM N2UHC/B ST PAUL KS. 5/Dec/2022 (Salmaniw, Masset, BC)

28212.1 AC7GZ 2140 CW A regular visitor to Masset. Fair to good this afternoon with VVV DE AC7GZ DM43BI 5/Dec/2022 (Salmaniw, Masset, BC)

28215 KA9SZX 2142 CW A slower rate beacon at good reception: VVVV KA9SZX KA9SZX KA9SZX BCN MACOMB IL PWR 3W GRID EN40PK EMAIL KA9SZXWAYAHOO.COM Now that’s a full information beacon! 5/Dec/2022 (Salmaniw, Masset, BC)

28217.7 K4PAR 2152 CW Very weak, but fully decodable with VV DE K4PAR/B. Listed as from the Piedmont ARC and 25 W. Just barely audible. 5/Dec/2022 (Salmaniw, Masset, BC)

28220.15 AA8HS 2155 CW Measuring below their listed 28.2203 frequency. Weak but in the clear. 5/Dec/2022 (Salmaniw, Masset, BC)

28232.3 W7SWL 2206 CW Now that’s a call-sign! He wasn’t there a few minutes ago, but noticed a very powerful beacon. VVV DE W7SWL W7SWL TUCSON AZ DM42 and repeated. 5/Dec/2022 (Salmaniw, Masset, BC)

28254.5 K4JEE 2220 CW Another beacon I recognize from previous sessions. Fair to good reception this afternoon with VVV DE K4JEE/B K4JEE/B K4JEE/B LOUISVILLE, KU EM78. 5/Dec/2022 (Salmaniw, Masset, BC)

28255.8 WI5V 2226 CW Weak reception, with some AM QRM. VVV DE WI5V/B 5/Dec/2022 (Salmaniw, Masset, BC)

28278.5 WA4OTD 2228 CW Weak, but in the clear with callsign and location. 5/Dec/2022 (Salmaniw, Masset, BC)

28280 K5AB 2231 CW Strong reception with DE K5AB EM01BEACON, repeated, then CENTRAL TEXAS 5/Dec/2022 (Salmaniw, Masset, BC)

28281.1 W8EH 2234 CW 100 Hz above their listed frequency at fair level with callsign and grid square reference. 5/Dec/2022 (Salmaniw, Masset, BC)

28284.8 N9TNY 2237 CW Strong reception with callsign and grid square reference. 5/Dec/2022 (Salmaniw, Masset, BC)

28236.5 W0KIZ 2243 CW Again, a beacon not there a few minutes ago, but really burning up the receiver with repeated VVV DE W0KIZ/B DENVER COLORADO 5 WATTS. 5/Dec/2022 (Salmaniw, Masset, BC)

28240 W8EDU/B 2223 CW Weak, but readable. For only a watt, I’m impressed! Giving callsign and grid square location. Found them on the dl8wx.de beacon website. Location and operator is the Case Western Reserve University amateur radio club. 8/Dec/2022 (Salmaniw, Masset, BC)

28252.5 WD8INF 2227 CW Good reception with callsign and grid square locatioon (EM79). 8/Dec/2022 (Salmaniw, Masset, BC)

28258.5 AC5JM 2229 CW Good copy with callsign and OK repeated. 8/Dec/2022 (Salmaniw, Masset, BC)

28277.56 WA4OTD 2232 CW Fair copy. Listed in the WI5V beacon website on 28.2788, so a bit lower in reality. Giving callsign, grid square, and CARMEL 8/Dec/2022 (Salmaniw, Masset, BC)

28281.1 W8EH 2235 CW Good reception with callsign and grid square (EM79). Clearly, Ohio is coming in well this afternoon. Normally I’m hearing AC7AV on or near this channel (Green Acres, WA). 8/Dec/2022 (Salmaniw, Masset, BC)

28284.8 N9TNY 2237 CW Strong signal with VVV DE N9TNY/B EN51 PSE RST. 8/Dec/2022 (Salmaniw, Masset, BC)

28271 W4ZZK 2245 CW A very weak signal heard while monitoring another very adjacent signal. , giving the callsign/B. CW Skimmer comes through again! 8/Dec/2022 (Salmaniw, Masset, BC)

28290.8 K5TLJ 2302 CW Weak reception, but able to copy AR AR AR DE K5TLJ/B K5TLJ/B K5TLJ/B AR Band is quickly fading, so looks like this is the top frequency beacon I can hear now. 8/Dec/2022 (Salmaniw, Masset, BC)

28250 K5AB 2341 CW A this late hour, very little propagating in the 10M Beacon band. Nonetheless, good reception from this high power beacon with DE D5AB EM01BEACON DE D5AB CENTRAL TEXAS. 14/Dec/2022 (Salmaniw, Masset, BC)

28268.334 VK8VF 2344 CW My first Australian beacon! Very weak, but the call sign is being decoded by CW Skimmer. Not even visible on the waterfall. 334 Hz high compared to the listed 28.268 on the WI5V Beacon website. 14/Dec/2022 (Salmaniw, Masset, BC)

28189 VE4TEN 2100 CW Great reception this afternoon. The band had many 10 M beacons, but unfortunately, I had other family matters today. Still, nabbed this one, with an interesting call, and flea powered as well. 18/Dec/2022 (Salmaniw, Masset, BC)

28193 LU2DT 2355 CW My surprise for the afternoon, and my first Argentinian beacon. Fair reception. Long, somewhat garbled tone, followed by VV DE LU2DT LU2DT GF12FA. Distance approximately 12,432 kM with bearing 125 degrees! 19/Dec/2022 (Salmaniw, Masset, BC)

I hope that I’ve wetted your appetite into trying something, “completely different” in our radio monitoring hobby. Who knows next what I’ll want to try!

Walter Salmaniw, Masset and Victoria, BC

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

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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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Small Unidirectional Loop Antenna (SULA) Part 2: Construction Notes

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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. This second article focuses on construction notes. The third and final article will essentially be a Q&A about the SULA antenna. All articles will eventually link to each other once published.

Please enjoy and share Part 2:

Part 2: SULA Construction notes

by 13dka

The drawing [above] has all you need to know. You basically need to put up a symmetrical wire diamond starting with a balun at the one end and terminating in a resistor at the other end of the horizontal boom, the sides are supposed to be 76cm/29.92″ long so you need to make yourself some…

Support structure:

I used 0.63″/1.6cm square plastic square tubing/cable duct profiles from the home improvement market to make the support structure. You can use anything non-conductive for that of course, broom sticks, lathes… The plastic profiles I used had the advantage of being in the house and easy to work on with a Dremel-style tool and everything can be assembled using the same self-tapping screws without even drilling. The profiles are held together with 2 screws, for transport I unscrew one of them and put that into an extra “parking” screw hole on the side, then I can collapse the cross for easy fit into the trunk, a rucksack etc.

These profiles are available in different diameters that fit into each other like a telescoping whip. This is useful to make the support structure variable for experiments and to control the loop shape and tension on the wire. The booms end up at 1.075m each, the profiles come in 1m length, so that’s 4 short pieces of the smaller size tube to extend the main booms by 37mm on each side

On the resistor end of the loop that smaller tube isn’t mounted in the “boom” tube but to the side of it in order to keep the wire running straight from the balun box on the other side.

Mast/mounting:

You can use anything non-conductive to bring it up to height. On second thought that is indeed bad news if you were planning on putting that up on your metal mast…and we have no data on what happens when you do it anyway. I don’t know if the smallest (4m) telescoping fiberglass poles would suffice for portable operation, but I’m a fan of just using the big lower segments of my 10m “HD” mast for the stiffness they give me (3 segments for the height, the 4th collapsed into in the base segment for easy rotation). Telescoping masts also give you easy control over…

Height:

The published patterns are for 3m/10′ feedpoint height over “average” ground. Increasing height further has no expectable advantage, instead it will deteriorate the favorable directional pattern of the loop. Flying it lower, or even a lot lower in windy weather on the other hand is causing a surprisingly moderate hit on performance.

Continue reading →

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Introducing the amazing SULA: An affordable unidirectional DX-grade loop antenna that you can build!

43 Replies

Many thanks to SWLing Post contributor extraordinaire, 13dka, who brings us 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 will focus on construction notes. The third and final article will essentially be a Q&A about the SULA antenna. All articles will eventually link to each other once published.

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 SULA Part 1:

Introducing the Small Unidirectional Loop Antenna (SULA) 1-30MHz

A small and simple, unidirectional and DX-capable loop “beam” for SWLs!

by 13dka

In early June, Andrew (grayhat), SWLing Post‘s resident antenna wizard suggested a variation of the “cardioid loop” on the SWLing Post message board: The original “cardioid loop” is a small loop receiving antenna deriving its name from a cardioid shaped (unidirectional) radiation footprint. The design is strikingly simple but it has a few downsides: It relies on a custom preamp, it needs a ground rod to work and it is unidirectional only up to 8 MHz.

Andrew’s version had the components all shuffled around and it did not only lose the ground rod, it also promised a nice cardioid pattern over the entire shortwave, from a small, diamond shaped loop. Wait…what? It can be made using parts available on Amazon and your DIY store:

You need some 3m wire and PVC tubes to create a support structure to hold the wire, a 530 Ohm resistor and a 9:1 balun like the popular “NooElec One Nine”. Since it’s a “lossy” design, adding a generic LNA like the NooElec “LANA HF” would help getting most out of it. When you put that all together you have what sounds like an old shortwave listener’s dream: a small, portable, tangible, and completely practical allband shortwave reception beam antenna with some more convenient properties on top, for example, it is a bit afraid of heights.

That sounded both interesting and plain crazy, but the .nec files Andrew posted were clearly saying that this antenna is a thing now. Unfortunately Andrew suffered a little injury that kept him from making one of those right away, I on the other hand had almost all the needed parts in a drawer so I ended up making a prototype and putting it through some of its paces, with Andrew changing the design and me changing the actual antenna accordingly, then mounting it upside down. Let me show you around:

Small, diamond shaped wire loop (with 76cm/29.92″ sides), needing as little space as most other small loops.
Unidirectional with a ~160° wide “beam” and one pronounced minimum with a front/back-ratio of typically 20dB over the entire reception range 1-30MHz.
Moderate height requirements: It works best up to 3m/10′ above ground, where it gives you…
…a main lobe with a convenient flat takeoff angle for DX
Antenna is comparatively insensitive to ground quality/conductivity.
Wideband design, works best on shortwave and is pretty good up to 70cm.

A functional small beam antenna for shortwave reception that’s just as small and possibly even more lightweight (prototype:~250g/9oz) than your regular SML, that can be easily made out of easy to obtain parts and easily carried around for mobile/portable DXing and due to its cardioid shaped directional pattern also for direction finding, a “tactical” antenna that’s also doing DX? Unlike conventional, Yagi-Uda or wire beams it can achieve a low takeoff angle at only 3m/10ft height or less, the front/back ratio is typically better than that of a 3-element Yagi, with a particularly useful horizontal pattern shape. That it’s rather indifferent to soil quality could mean that more people get to reproduce the good results and being a real wideband antenna is making the SULA an interesting companion for multiband radios and SDRs. Really? A miracle antenna? Is it that time of year again? If I had a dollar for every….

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International Radio Club’s Reprints collection of 900+ articles

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Many thanks to SWLing Post contributor, Nick Hall-Patch, who shares the following announcement:

The International Radio Club’s Reprints collection of 900+ articles about antennas, radio propagation, receivers, accessories, plus items of general interest to MW DXers, continues to grow. We’ve published an update to the index, at https://www.ircaonline.org/editor_upload/File/reprints/irca-reprint-index.pdf , so that everyone can get access to these latest additions.

We’re also pleased to start offering reprints that did not initially appear in IRCA’s DX Monitor, but are not easily found elsewhere. For example, we’ve obtained permission from the family of the late prolific author, Dallas Lankford, to organize and republish his out of print articles.

(if you’ve used the index before, you may need to refresh the browser page to see the latest update, dated December 2021)

Click here to check out the IRCA Index (PDF).

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CBC Yukon features Finnish DXer who logged their station from 7,000 km away

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Image Source: CBC/Google Earth

(Source: CBC Yukon)

From Yukon to Finland: CBC’s radio signal heard from afar

Host Elyn Jones heard saying ‘this is Yukon Morning,’ about 7,000 kilometres away

A keen listener has managed to hear CBC Yukon’s radio broadcast from about 7,000 kilometres away.

Jorma Mäntylä lives in Kangasala, Finland.

On Oct.15 he was scanning the airwaves and came across the signal from Dawson City, Yukon, broadcasting CBC’s Yukon Morning show.

The signal lasted about an hour.

“It was clear to hear your Yukon Morning program led by a female journalist and the morning news,” he said.

The host that day was Elyn Jones in Whitehorse.

Upon hearing the signal Mäntylä sent an email with an attached audio clip asking for confirmation.

CBC Yukon wrote him back to confirm what he’d heard. We also scheduled an interview by videoconference to speak about his hobby.

No ordinary radio

Mäntylä doesn’t have an ordinary radio. He’s part of the Suomen Radioamatööriliitto, the Finnish Amateur Radio League.

He started listening to signals in 1967.

He uses custom-built equipment to scan for shortwave and AM radio signals.

Sometimes it takes a while, through the crackle, to determine the language being spoken and from where the signal is broadcasting.

The game is to discover new stations, identify them, and then send an email to confirm the reception.

“I very often listen to foreign radio stations. That has been my hobby for 50 years,” he said. ‘It’s given me interesting moments learning about other cultures and nations,”

Hearing a signal from Yukon is rare. Mäntylä says on Oct. 15 he also heard broadcasts from radio stations in Anchorage and Fairbanks, Alaska.