Category Archives: Antennas

A HUGE difference . . .

By Jock Elliott, KB2GOM

It was a remark from Sebastian Schlüter in response to this post – https://swling.com/blog/2025/10/some-really-inexpensive-ways-to-perhaps-improve-your-shortwave-listening — that sparked today’s post.

He said:

If your RFI is really high, your best weapon is a magnetic loop antenna aka small receive loop. At home, my RFI is so high that I don’t benefit from a larger/longer antenna. For example: Using the telescopic antenna (75 cm) vs using 3m of wire. Reason is that the signal-to-noise ratio is roughly the same in both cases and that all of those very weak signals are below the noise floor anyway, and the ones that make it through the noise are already strong enough to be received with the telescopic only. Conclusion: In a high RFI environment, it’s not about maximising the signal strength but maximising the SNR. You need to find an antenna type that will pick up less of that RFI. A cheap and simple antenna for this is the small receive loop. For a start, you can use a cheap wire terminal with 3.5mm mono jack. Using a 1:1 balun further improves the result.

What really struck my eye was this:

A cheap and simple antenna for this is the small receive loop. For a start, you can use a cheap wire terminal with 3.5mm mono jack.

My CCrane Skywave SSB 2 came with a wire terminal with a 3.5 mono jack, I realized. I hooked it up to my 45-foot horizontal room loop (a single strand of insulated wire run around the top of window frames and bookcases in my radio shack), and then ran the following experiment.

Using the scan function on the Skywave SSB 2, I scanned the shortwave bands using the whip antenna, and then I did it with the loop plugged into the external antenna socket.

The results:

CCrane Skywave SSB 2

Whip antenna: 4 stations detected. Loop antenna: 13 stations detected.

Then I tried the same experiment with a Tecsun PL-880.

The results:

Tecsun PL-880

Whip antenna: 8 stations detected Loop antenna: 15 stations detected.

Clearly, Sebastian’s suggestion of plugging in a simple wire loop makes a huge difference. And, I should note, I didn’t play fair. I did the test while 3 scanners, an LED light, and two UHF/VHF ham transceivers were operating in the vicinity and probably generating RFI.

So now the question: I ran the experiment with a 45-foot simple loop. What do you suppose would be the minimum wire length for an effective simple wire loop? I look forward to your input.

Coupling Three Homebew Antennas for 40-Meter DX

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.]

Giuseppe’s Multi-Band Milk Crate Loop Antenna

6 Replies

Many thanks to SWLing Post contributor Giuseppe Morlè, who shares the following guest post:

Dear Thomas and Friends of SWLing Post,

I am Giuseppe Morlè from Formia, a town in central Italy on the Tyrrhenian Sea.

I have built a new “Multiloop” antenna using a 40 cm diameter milk crate. The crate is very sturdy and shockproof, making it an excellent base for this project.

Construction Details

I wound three different loops on the crate:
1. A single shortwave coil
2. Two shortwave coils
3. Twelve medium-wave coils

The design includes a single coil placed between the two shortwave coils, which picks up the signal by induction and transfers it to the receiver via an RG58 cable.

The heart of this system is a 2,100 pF variable capacitor with sockets connected to the rotors. Inside the crate, I added another 18 cm diameter loop positioned just below the two main coils.

The ends of this small loop are attached with crocodile clips to the external ends of the rotor. This small loop allows me to exploit induction and, by turning the capacitor, access all decametric bands from 160 to 10 meters.

Tuning Ranges

The variable capacitor enables tuning as follows:

- - In the lower ranges, it covers 80 to 20 meters.
  - When reversed, it tunes all higher ranges from 10 to 20 meters.

This works because the small loop and capacitor couple inductively with the primary turns. By increasing capacity with cables on the rotors, the antenna can even tune up to 160 meters.

The medium-wave turns cover frequencies from 300 kHz to 1,900 kHz. Essentially, this Loop Milk Crate antenna can access a wide range from 300 kHz to 30 MHz.

Testing and Comparisons

I tested the antenna using the Tecsun PL-660 and the Tecsun S-8800 receivers. I also compared the Loop Milk Crate with my “Ferritona” antenna and found surprising results!

Some of the videos were filmed in my shack because it was too cold to work on the balcony. Other videos were shot outside, either on my balcony or on the beach in Formia.

Videos

Final Thoughts

I hope you enjoy my “crazy” constructions. Always remember, I’m not a technician—just a passionate listener who loves building with recycled materials.

Wishing everyone a year full of happiness and satisfaction!

Best wishes to all,
Giuseppe Morlè

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

The Great Gonzo Radio Experiment

13 Replies

By Jock Elliott, KB2GOM

It’s funny how you can start out thinking about how to solve a problem, the whole process takes a turn, and you wind up with an unexpected but pleasing result.

It all started innocently enough. Alan posted this — https://swling.com/blog/2024/11/bbc-rd-how-to-test-a-loop-antenna/ — and this statement appeared at the end of a BBC report on how to test loop antennas:

“Polarisation Illustrations of the antenna usually show it mounted upright; that is, with
its axis parallel to the ground. This is fine for the reception of LF and MF transmissions, which are vertically polarised, but most HF transmissions are horizontally polarised.”

When I tested that assertion here — https://swling.com/blog/2024/12/here-we-go-loop-de-loop-in-which-your-humble-correspondent-tests-a-hypothesis/ — there were a couple of interesting responses.

Bob Colegrove said (in part):

“To address your conundrum, from my long-standing, untutored tinkering with loop antennas, I have concluded that, regardless of LW, MW, or SW, optimum performance for peaks and nulls requires that the axis of the loop (i.e., line through the center of the coil) be able to rotate 360 degrees laterally and 90 degrees vertically.” (emphasis mine)

Robert Gulley added:

“I will have to concur with Bob – if I may state it another way, there is no “proper” position for a loop when getting shortwave signals.”

To which I responded:

“I suppose the ultimate setup might be an articulated motorized outdoor mount with a joystick inside that would allow me to fiddle the loop to the optimal position.”

Early in the morning I awoke thinking about how a system capable of manipulating my three-foot-diameter MFJ 1886 loop both vertically and horizontally might be implemented. Everything that came to mind seemed awkward, hard to put together, difficult to operate, expensive, and just plain clunky.

I dozed off and woke up thinking: “What about a really small loop? I could hold it in my hand and easily turn it to different positions to optimize reception, no equipment required.”

A thought came to mind: “You’ve got a small loop antenna, why don’t you see what you can do with it?”

At this point, I need to make my Shameful Admission: I got so intrigued by the idea of using my wrist and hand to turn a small loop to various orientations that I forgot that I was trying to solve the problem of manipulating a shortwave loop.

The loop that came to mind is the Terk AM Advantage. I tested it here. Designed to boost signals on medium wave, it is a nine-inch tunable loop encased in plastic that requires no power supply. It inductively couples with the ferrite antenna inside a portable radio. But I seemed to recall that it also comes with a direct wire connector that can be used with some radios. Perhaps I could connect it to my CCrane EP-PRO which has clips and a switch for an external medium wave antenna on the back of the case.

I found the Terk AM Advantage easily enough, but the direct wire connector required a major archeological dig. Once I unearthed it, I plugged the connector into the back of the Terk AM Advantage, slipped the wires from the connector into the clips on the back of the EP-PRO.

Now to try it out . . .

Tuning slowly down the dial, I found across a very faint signal that I could barely copy. Reaching around the back of the EP-PRO, I switched from the EP-PRO’s internal antenna to the Terk AM Advantage external loop antenna (which I was holding in my hand), rotated it from side to side, tipped it back and forth, and – tah-dah! – was rewarded by a far more copyable signal. It was WEEU in Reading PA, 200 miles away, transmitting 6,000 watts into the darkness on 830 kHz. Switching back to the EP-PRO’s internal antenna, I tried rotating the EP-PRO to optimize the signal but could not produce a signal that was as good as the external loop.

Repeating the procedure with additional faint stations, I got the same results: better reception with the handheld loop antenna, and it was fun and easy to use. I held it in my left hand (it’s light) so I could rotate the dial that peaks the signal with my thumb and working the tuning knob on the EP-PRO with my right hand. It was a very pleasing, almost addictive, experience.

If you’re looking for a potent setup for medium wave DXing, I can recommend the EP-PRO/Terk AM Advantage combo, even though it wasn’t my original objective. Call it serendipity.

In the meantime, does anyone know what might be the smallest loop that could be handheld for shortwave reception and would provide a performance boost over a whip antenna?

Here we go loop de loop . . . in which your humble correspondent tests a hypothesis

16 Replies

By Jock Elliott, KB2GOM

It was this post by Alan — https://swling.com/blog/2024/11/bbc-rd-how-to-test-a-loop-antenna/ — that set me off. After downloading the BBC report on how to test a loop antenna, I noticed the following in it:

“Polarisation Illustrations of the antenna usually show it mounted upright; that is, with
its axis parallel to the ground. This is fine for the reception of LF and MF transmissions, which
are vertically polarised, but most HF transmissions are horizontally polarised.”

Huh, I thought, “I wonder this would have any bearing on how I use my MFJ 1886 loop antenna?

So hooking the 1886 loop to an SDRplay RSPdx, here’s what the spectrum looks like on medium wave in vertical orientation with the 1886’s internal amp turned on:

And here’s what the medium wave spectrum looks like with the loop in horizontal orientation, amp on:

But what about shortwave reception? Here’s 31 meters in vertical orientation:

And here’s 31 meters with the loop in horizontal orientation:

Here’s 25 meters in vertical orientation:

Here’s 25 meters in horizontal orientation:

It looks to me, at the very least, the noise floor is lower . . . or I am in desperate need of a laxative?

For more about my adventures with the 1886 loop, check this — https://swling.com/blog/2022/10/testing-the-mfj-1886-receive-loop-antenna/ — and this — https://swling.com/blog/2023/01/saturday-morning-fun-fat-mw-dxing-with-the-mfj-1886/

My conclusions: I definitely don’t want the 1886 loop in horizontal orientation for medium wave DXing, but I think that the flat orientation might help for shortwave DXing.

What do you think?