Tag Archives: Loop Antennas

Bill tweaks his AM loop antenna for optimal mediumwave performance

Many thanks to SWLing Post contributor, Bill Hemphill (WD9EQD), who writes with the following update to his previous post:

As you may remember, back in May, I picked up a beautiful home-made loop antenna. It was 25 inches on a side with 23 turns of wire. My initial testing showed that it would tune from 280 kHz to 880 kHz. While I was familiar with loop antennas, I had never tried using one.

My initial tests were disappointing. So I spent some time on the internet reviewing AM loop antenna designs. I came across a reference to an AM Loop Antenna Calculator by Bruce Carter:

http://www.earmark.net/gesr/loop/umr_emc_calc.htm

I first measured the tuning capacitor and found that it tuned from 25 to 400 pF. Entering the data into the calculator:

This matches closely to what I was experiencing.

I then proceeded to calculate various Number of Turns to see the effect on tuning range. My goal was to tune the entire AM broadcast band.

I settled on ten turns which gives the following from the calculator:

Perfect. I removed 13 turns (which left ten turns) and then added a two turn secondary loop which would be connected to the radio. The results were fantastic.

I have created three short videos showing the difference between using the Tecsun S-8800 without the loop on a weak station and then using it with the loop.

[Note: If you’re viewing this post via our email newsletter you might need to view this post via a web browser to see the following embedded videos.]

Without the loop

With Loop

As you can hear, a very noticeable difference.

[After making these videos] I tested the of reception of 1510 kHz on the Panasonic RF-2200:

The results are amazing.

I have logged three stations on one frequency. Just peak the one station, then tune the loop and peak the second, then turn the loop some more and peak a third station.

I’m having a lot of fun with the loop. When it gets a little cooler, I plan to take it to the park where there is zero noise and really put it through its paces.

Excellent job, Bill! You’ve proven that doing a little research and making small adjustments to an antenna design can yield impressive results! Thank you for sharing!

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Bill scores a homebrew LW/MW magnetic loop antenna

Many thanks to SWLing Post contributor, Bill Hemphill (WD9EQD) who shares the following:

I went to the Warminster Amateur Radio Club (WARC) hamfest [yesterday] in Bucks County, PA. For some time, I have been thinking about making a loop antenna for AM DXing. It was my lucky day. When I walked to the inside tables, on the very first table was this homemade loop antenna gentleman was selling from an estate.

I snatched it up for $40.

Attached are some photos of it. It’s 25” by 25”, with a swivel base. There are 23 turns of wire and I have no idea what size the capacitor is. I did some preliminary tests and it tunes from 280 kHz to 880 kHz. So it’s the covers the high half of the long wave band and the low half of the AM band.

It’s very well made and I fugue I can modify it to cover the entire AM band.

[…]I hooked the SDRplay RSP2 to it and was getting good signals of major stations all the way to 15 mHz.

That’s with it sitting on my dining room table. Of course the capacitor wouldn’t peak the signals.

So it was a great day at the hamfest!

Indeed that was a great find, Bill!  Someone spent a decent amount of time building that furniture-grade loop support. Indeed, it’s very reminiscent of 1920s-30s mediumwave loops!

What I love about your loop (and that of Thomas Cholakov) is that one can see how simple these antennas actually are to build. The only complicated bit is the support, but even that’s simple if you use the shield of a heavy coax or flexible copper tubing.

Thanks for sharing and enjoy logging DX with your new-to-you loop!

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Video: Homebrew AM Loop Antenna Project by Thomas Cholakov (N1SPY)

Many thanks to SWLing Post contributor, Thomas Cholakov (N1SPY), who shares his latest video explaining the operation of a simple homebrew AM loop antenna:

Click here to view on YouTube.

Brilliant video, Thomas! I love the fact you included a demonstration with your SDRplay RSP1A as well. Via the spectrum display, it’s easy to see the the loop’s bandwidth and also the gain it provides when tuned to a station.

I love your AM loop antenna as well–such a simple design and ideal for demonstrating the mechanics of a passive loop antenna since all of the components are visible. I’m willing to bet you built this antenna for less than $10. Smart design as it’s both portable and effective! Keep up the excellent work, Thomas! We look forward to all of your future videos.

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Kenneth is impressed with the W6LVP Magnetic Loop Antenna

Many thanks to SWLing Post contributor, Kenneth Wigger, who writes:

One Friday evening I contacted Larry W6LVP and asked a question about the kind of coax that he would recommend for his Magnetic Loop antenna. I was surprised to get a response with technical information within an hour or so. With this kind of customer service I decided to go ahead and order one of his antennas later that evening. I actually received the antenna on Monday afternoon within a couple days.

I have extreme electrical noise that was S-8 most of the time on my Carolina Windom and made my radio almost unusable. I temporarily installed the Magnetic Loop antenna on a short 5 FT pole in the backyard. With the XYL as the null monitor at the radio I called her on my cell phone and rotated the antenna by hand and was able to get a sharp noise null of about S-1. Very tight null when rotating just a few degrees one way or the other. Went in the house and couldn’t believe the clear signals that were hidden by the previous high noise level. It reminded me of SWLing 50 years ago as a kid back in the good old days before the electrical noise environment turned so bad!

As I mentioned, the antenna arrived within a couple days and was of high quality construction and packed extremely well for shipment. I had read the previous reviews about Larry’s product quality and customer service and my experience was also very good!!

I am planning to mount the antenna on a Channel Master rotator one of these days to get the full effect of the excellent directionally of this Magnetic Loop antenna. I even read where Broadcast Band Listeners use this antenna to pick up and select between multiple stations on the exact same AM frequencies.

I highly recommend Larry W6LVP and his Magnetic Loop antenna to other Hams and SWL listeners. He responds personally to emails within a business day usually just an hour or two. What more could a customer ask for?

Thank you, Kenneth, for sharing your review! It’s nice to have an alternative to the pricier Wellbrook and Pixel Loop antennas. Someday, I’ll get around to reviewing the W6LPV loop antenna as well.

Click here to view W6LVP antennas on eBay.

Click here to view the W6LVP website.

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Horizontal Loop Antenna Experiments

Man-made RF noise levels have increased dramatically at my place in the past six months. It has become much harder to hear weaker shortwave signals. Even the stronger stations are getting covered in all types of hash from all manner of electrical appliances.

So, I have been looking at ways to reduce the noise problem. I’m currently researching a few possible solutions, including trying a different antenna.

The HF horizontal loop has been around for many years now, but it’s a new antenna for me. I’ve never had a need to try one…..until now! There is some documentation out there praising this antenna’s low noise capabilities. So, it was time to find out for myself and start building an experimental version. So far, the results have been really quite pleasing!

I have prepared a YouTube video (below) in which I discuss the reasons for looking at this antenna, its design, and its installation. I also do some on-air comparisons of my experimental rectangular (!) version of the horizontal loop against my three regular double bazooka (coax) dipoles and the Par SWL End-Fed antenna.

Have you tried this antenna before? Your thoughts and feedback would be most appreciated.

73 and good DX to you all,

Rob VK3BVW

Rob Wagner, VK3BVW, is the author of this post and a regular contributor to the SWLing Post. He also blogs at the Mount Evelyn DX Report.

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