Tag Archives: Antennas

Portable Antennas for Serious DXing: Don’s Field Tests from Parks to the Open Road (Part 1)

Many thanks to SWLing Post contributor Don Moore–noted author, traveler, and DXer–who shares the following post:

Two Portable Antennas for Remote DXing (Part One)

By Don Moore

Don’s traveling DX stories can be found in his book Tales of a Vagabond DXer [SWLing Post affiliate link]. If you’ve already read his book and enjoyed it, do Don a favor and leave a review on Amazon.

Once upon a time, I had a traditional DX shack with an L-shaped desk and shelves of receivers, radio gadgets, and DX books. Everything I wanted or needed as a DXer was right at hand. Then I retired and was finally able to pursue my lifelong itch for serious travel. But there was no way to carry that DX shack along with me. Fortunately, modern technology was there to help. SDRs are significantly more travel-friendly than my old Sony ICF-2010 (let alone the Drake R-8). Instead of books and bulletins, my DX reference materials are websites and PDF files on my laptop.

I spend several months a year traveling internationally with just a suitcase and knapsack. That doesn’t leave much room for DX equipment. Several years ago I described my approach to vagabond DXing in an article here.

https://swling.com/blog/2019/03/radio-travel-a-complete-sdr-station-for-superb-portable-dxing/

Since writing that article in 2019, I’ve continued to work on making my portable DX shack better and more compact. Recently, I replaced the Elad FDM-S2 with three Airspy HF+ Discovery SDRs. Not only are they smaller and lighter, but I can record three different band segments at once. Next up was rethinking my travel antennas. A wire loop with the Wellbrook ALA-100LN is still, in my opinion, the best travel antenna. But the components are heavy and are now irreplaceable since they are no longer made. So over the summer, I set about testing and comparing both old and new options. But you don’t have to wander the globe for my findings to be useful to you. This can be just as helpful for DXing from a nearby park. That’s how I did my testing.

I spent the past summer staying at an AirBnB in the north Chicago suburbs. I wanted a better location for testing so I checked out parks in the area and finally settled on Preserve Shelter B (42.26797, -87.92208) at the Old School Forest Preserve, east of Libertyville in northern Illinois. The shelter was entirely wood, with standard asphalt shingles (rather than steel), and had no nearby power lines. I made four daytime DXpeditions there to do some utility DXing and to run my tests. Here’s a photo of my setup.

I decided I should rerun the tests at least one other location. So while driving across the US in mid-October, I stopped for a few hours one morning at Park Shelter A (39.11144, -94.86629) in Wyandotte County Park, just west of Kansas City, Kansas. There, I just had a minimum setup.

The Antennas

So, what were the antennas I was testing? The first was the tried-and-true PA0RDT mini-whip from Roelof Bakker. The PA0RDT is described in my 2019 article and is probably the most portable quality antenna you can get. To power it I use a battery box and eight rechargeable lithium-ion AA cells.

For the traveling DXer, setting up the PA0RDT is as easy as it comes. I just attach the coax cable and throw it over a support, such as a picnic shelter beam or a tree branch.

But I’ve always believed that the best antenna is another antenna. That is, every antenna works differently, and therefore the more options you have, the more likely you will have something that works well in any situation. So if I wanted to leave the Wellbrook at home, what might complement the PA0RDT? I contacted my friend Mark Taylor, who I knew had a large collection of the various inexpensive Chinese-made amplified loops. With his help, I settled on the MLA-30+ MegaLoop from DmgicPro.

This antenna consists of a steel wire loop that connects to terminals on the amplifier box. The amplifier has a ten-meter coax cable, which in turn is connected to a small bias-T power supply, which gets its power via a USB connection. The MLA-30+ is designed to be used in a permanent installation with some sort of vertical support, such as a PVC pipe. Some users replace the wire loop with copper tubing.

Those options aren’t practical for me, and simply hanging the antenna from the top would cause the steel loop to stretch and deform. So I came up with the idea of tying a strong cord from the top to the bottom of the loop so that the cord, and not the loop, bears the weight. To hang the antenna, I throw the cord over the support, attach the antenna, and then pull it up into place. That works well if you have rear support to hold it in place, such as the beams of a picnic shelter.

It’s a bit more difficult to mount the MLA-30+ in a tree.

Comparing the Antennas

I ran comparisons between the antennas several times at Old School Forest Preserve and then again at Wyandotte County Park. The results were practically the same every time. The images below were made at Old School unless otherwise stated.

The PA0RDT was designed to be a good performer on longwave and medium wave. Unsurprisingly, it shows a lot of signals on the upper end of the medium wave band, even during the daytime. Except for being non-directional, the PA0RDT is an excellent MW antenna.

The MLA-30+, on the other hand, isn’t good for much beyond hearing the strongest local signals on medium wave.

When I ran these tests in the late morning, WWV on 5 MHz was the only signal in the 60-meter band. It had a very listenable signal on the PA0RDT.

But on the MLA-30+, WWV was barely there.

Likewise on 49 meters, CFRX on 6070 kHz was very clear on the PA0RDT but barely listenable on the MLA-30+. But when I moved up to 31 meters, the difference between the antennas mostly disappeared, as in these images made in Kansas. The PA0RDT is top and the MLA-30+ on the bottom.

On 25 meters, the PA0RDT is picking up a lot of noise and the signals are not that strong. Nor were signals very strong on 19, 16, 0r 13 meters.

However, on 25 meters with the MLA-30+ there isn’t much noise and the signals are booming in. And 19, 16, and 13 meters likewise had strong signals.

So the PA0RDT is clearly the best antenna for MW and the lower shortwave bands, but it doesn’t do as well on the higher bands. This wasn’t a surprise to me as I’ve always felt that the PA0RDT underperformed above nine or ten Megahertz. The MLA-30+ was abysmal at the lower frequencies but worked better or just as well in the middle and higher shortwave bands. The best antenna is another antenna. Each one performs better in different situations. But I couldn’t help but wonder … was the problem with the MLA-30+ that small steel wire loop?

Look for Don’s Part 2 article next weekend on the SWLing Post!

Giuseppe’s Ingenious Recycled Antenna Board for SW & MW Listening

6 Replies

Screenshot

Many thanks to SWLing Post contributor Giuseppe Morlè, who writes:

Dear Thomas,

I’m Giuseppe Morlè, IZ0GZW, from Formia, in central Italy on the Tyrrhenian Sea.

I’d like to show you my antenna board for shortwave and mediumwave listening with portable receivers like the Tecsun PL-660.

The board has two distinct circuits:

- - A small-diameter loop with two turns for shortwave reception (3.5–18 MHz).
  - Three ferrite rods with 30 turns each, plus a four-turn link coil that carries the signal to the receiver for mediumwave reception.

In the video, you’ll see how the board works on its own, and then how performance improves when I connect a 15-meter wire and throw it over the balcony of my house. In that case, the signal becomes much stronger.

Tuning is done with a 900 pF variable capacitor. To listen to mediumwave, I simply disconnect one side of the shortwave loop. With just that single variable capacitor, I can tune all of the bands.

It’s a surprisingly effective antenna for small portable receivers, and it’s built entirely from recycled materials—at no cost.

I hope you enjoy it. Greetings to all the friends of the SWLing Post.

73, Giuseppe Morlè, IZ0GZW

Click here to view on YouTube.

Many thanks, Giuseppe, for once again sharing your creativity with us. I’m always impressed by the antennas you design and by the performance you achieve—especially considering they’re largely homebrewed from recycled parts. That’s radio at its very best!

[Note that his video is in Italian, but you can turn on subtitles for your preferred language.]

Simple Wire Antenna: Giuseppe’s Mediumwave DXing Adventures from the Tyrrhenian Sea

18 Replies

Many thanks to SWLing Post contributor, Giuseppe Morlè (IZ0GZW), who writes:

Dear Thomas and Friends of SWLing Post,

I am Giuseppe Morlè from Formia, Central Italy, on the Tyrrhenian Sea.

This time, I want to share a very simple antenna setup for listening to and attempting extreme DX on Medium Waves.

I first saw this antenna in several videos, and many DXers have used it during various expeditions.

For my setup, I used a 15-meter-long wire. At around 11 meters, I formed a small coil with 8 turns, then continued the wire for another 3 meters.

I began with some tests on my balcony by laying the wire flat along the ground for its entire length. I used my small Sony SRF-37V as a receiver. By placing the receiver within the coil of turns, I immediately noticed a significant difference compared to the built-in ferrite antenna.

In the early afternoon, I tuned into a Chinese language broadcast on 1377 kHz. You can watch a video of this experiment on my YouTube channel:

Encouraged by the excellent results, I decided to head to the tourist port of Caposele di Formia the next day in the early afternoon. I set up on the pier overlooking the sea. This time, I laid the wire in an eastward direction — towards the night, where the sun had already set, while it was still high for another two hours on my side.

Once again, I achieved amazing results.

I was able to hear the same Chinese station on 1377 kHz, but this time with much clearer audio than from my balcony, where electrical noise interfered. By the sea, the signal was clean and strong.

After a while, I tuned into VOA broadcasts from Thailand on 1575 and 1395 kHz, both with surprisingly good audio quality. You can see this second experiment here:

Sometimes, all it takes is a bit of wire and a small coil to create an excellent, ground-level antenna — in this case, oriented eastward.

I also tried using my loop cassette and a Tecsun PL-660 but couldn’t hear anything. Yet the little Sony SRF-37V proved itself to be a true “DX killer” on AM — truly impressive.

I even caught a segment of the VOA program “World Today,” discussing the Chinese economy and Southeast Asia.

As the sun set, the DX signals faded, making way for closer European and Asian broadcasters.

I will definitely return with a longer wire to see if this surprising setup can be improved even more.

A warm greeting to all the Friends who follow SWLing Post and to you, Dear Thomas.

73, Giuseppe IZ0GZW

A File Worth Having: Bob’s guide to building an Electrically Small Resonant Loop Antenna for Mediumwave Reception

11 Replies

Screenshot

This post is short and sweet.

If you click here–Electrically Small Resonant Loop Antenna for Mediumwave Reception (PDF)–you can download a copy of Bob Colegrove’s excellent paper on the Electrically Small Resonant Loop Antenna for Mediumwave Reception.

He has actually built this antenna; it works; and he uses it often. Perhaps you might want to build one for yourself. As an added bonus, Bob is an excellent writer (in my not-so-humble opinion). What’s not to like?

— Jock Elliott, KB2GOM

Dale Recomends the Aziloop DF-72 Antenna System

4 Replies

Many thanks to SWLing Post contributor, Dale Parfitt, who writes:

I wanted to mention a receive only antenna that I am using at my home QTH. I do a lot of NDB logging during the winter below 500kHz, some AM band DXing and 160M. In the past I have had Beverages, homebrew Flag antennas, Shared Apex Loop Array and now last month I installed the new Quiet Radio AziLoop:

https://www.quietradio.co.uk/

With the Array Solutions Model AS-SAL, I could electrically rotate in 45 degree increments and also flip the direction by 180 or make it bidirectional. Click here to download the manual (PDF).

You can read the features of the AziLoop on Dave’s site. But the outstanding feature is rotating electrically every 5 degrees and 2 modes- small RX loop and K9AY. In K9AY mode I can achieve up to 30dB F/B and the rear null is very sharp. If it did not rotate in 5 degree increments, you would not even see the rear nulls.

But here is where it really stands out. The K9AY design, like the flags and Ewes, has a terminating resistance. By varying the value of that resistance via the AziLoop App, one can achieve skywave nulls. The value of that terminating resistance changes from day to night etc. So using that feature, I can often reduce co-channel or adjacent channel QRM or thunderstorm QRN. Small loops (aka magnetic loops) cannot do that. They are omnidirectional to skywaves.

Anyway, I mention this as some of your site readers both ham and SWL might find it interesting.

I built mine from telescoping fiberglass poles and it is completely standalone- no loops on the ground stakes etc.

I have no commercial relationship with Quiet Radio- just a very satisfied client.

Thank you for sharing this, Dale. I was not aware of the Aziloop. Fascinating!

DICA 2: “The Revenge” – Giuseppe tests his updated homebrew antenna!

1 Reply

Many thanks to SWLing Post contributor, Giuseppe Morlè, who shares the following antenna project:

Dear Thomas and Friends of the SWLing Post,

I’m Giuseppe Morlè from Formia, central Italy on the Tyrrhenian Sea.

After the DICA prototype I created another one called DICA 2 The Revenge!

This other minimal antenna works differently from the prototype. It is shorter, has 3, 12 cm ferrites inside and has the sensors soldered inside in reverse on the telephone cable strap. It works coupled to a metal surface because it uses magnetic induction unlike the prototype.

In the videos you can see the differences between the prototype and the DICA 2…
and the yield on the highest ranges.

This small minimal antenna can tune listening from 3.5 to 30 MHz.

Thanks to you and greetings to all the Friends of SWLing Post.

73.

Videos

Video: Giuseppe explains wiring/construction of DICA Homebrew Antenna

1 Reply

Many thanks to SWLing Post contributor, Giuseppe Morlè, who writes:

Dear Thomas and SWLingPost Friends,

I’m Giuseppe Morlè iz0gzw,

Many friends have asked for the DICA wiring diagram after my recent post and demonstration.

I’m not a technician but a simple passionate listener and qrp’er… I made this video with a drawing that I hope will be useful to understand the details and how it works…

[Please note that this video is in Italian, but you can use YouTube Closed Captioning; it can even translate the subtitles into English or any other language.]

Thank you all.
Giuseppe iz0gzw.