Tag Archives: Magnetic loop

Giuseppe’s cross-loop experiments

Many thanks to SWLing Post contributor, Giuseppe Morlè (IZ0GZW), who shares the following:

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

I wanted to share with you and friends of the SWLing Post community this antenna project of mine dedicated to those who do not have enough space on the roof or in the garden to install antennas.

These are two separate loops, with two different diameters, one 60 cm, the other 90 cm, each with two variables for tuning … the system is able to receive from 3 to 30 MHz.

I joined these two loops in an opposing way, better to say crossed that can communicate with each other due to the induction effect that is created between the two small coupling loops that are placed one under the other at the top.

In the videos you will be able to see how the antenna system receives. I can use one loop at a time, to detect the direction of the signal or I can use them together for a more robust signal and in an omnidirectional way.

I really like experimenting with the induction effect and you can see that even when closed at home the two loops do a great job.

From my YouTube channel:

I’m not a technician but I really want to experiment to try to listen as well as possible.

Thanks to you and CIAO to all the listeners of the SWLing Post community.

Giuseppe Morlè iz0gzw.

Very cool, Giuseppe! I must say I’ve never tried dual loop experiments like this where one can experiment with the induction interplay. I imagine this could give you some interesting nulling capabilities if you have an unwanted station interfering with a target low-band signal. Thank you again for sharing!

Spread the radio love

Marty needs advice as he builds a passive magnetic loop antenna

7 Replies

Many thanks to SWLing Post contributor, Marty Kraft, who asked that I share the following question with our community:

I’m still working on a receive-only passive hula loop magnetic antenna for my Tecsun PL-660.

After viewing thousands of YouTube videos (LOL), I built the PVC-pipe structure [you can see in the photo below].

But I need some tech help to finish…

The antenna is 90 inches tall; large loop diameter is 40 inches; and small loop diameter is 17 inches. The wiring is 14 gauge braided.

I plan to put the antenna outside on the porch. Then I’ll run coax from the small loop to the receiver inside and use a 365 pF air variable capacitor to tune the large loop.

My first question is, what’s the best coax to use for the 10-ft run from the small loop to the radio inside? Second, will that 365 pF cap tune the entire 3-30 MHz range?

It’s hot here in Louisiana, so I’d really like to tune the capacitor from inside my apartment, also using coax to connect the cap to the large loop. Will that work? Or does the cap have to connect directly to the large loop?

Any other tips or suggestions? Thanks for the help!

Post Readers: If you have any helpful advice for Marty, please comment!

Spread the radio love

Building a 20 meter self-tuning magnetic loop antenna

1 Reply

I’m often asked about what’s involved with building a home brew magnetic loop antenna.

If you’re considering building a passive loop antenna–one designed to both transmit and receive without any sort of receiver amplification–it’s a simple project. With basic DIY skills, a little math, a good variable capacitor, some copper tubing or coax, and a few inexpensive parts, it’s easy to make a passive antenna designed to operate on a given portion of the HF spectrum. It can be an easy two hour build as long as you have all of the parts. There are a number of tutorials for doing this on the web and several books on the topic (one of my favorites is Joe Carr’s Loop Antenna Handbook).

The compromise with a passive loop design is that they tend to have a very narrow bandwidth. In other words, you might have to re-tune the antenna via the variable capacitor even if you only move the frequency 5-10 kHz or so.

Via Hackaday, I recently discovered this innovative self-tuning passive loop antenna design by Eric Sorensen. Eric implements a stepper motor to make tuning adjustments. Not necessarily a beginner’s project, but the principles are straight-forward. He even includes a link to his printed components.

Click here to view Eric’s 20 meter loop antenna project.

Spread the radio love

The W6LVP magnetic loop antenna

23 Replies

Many thanks to SWLing Post contributor, Troy Riedel, who asks:

Just curious if you or anyone you know have any experience with Magnetic Loops from W6LVP? […]Here’s his eBay page – 458 feedbacks and 100%.

Thank, Troy! I’ve never used the W6LVP loop, but the price–in comparison with other wideband mag loop receive antennas–is very attractive.

W6LVP currently offers two models of loop antennas:

Here’s the product description of the Mag Loop with Power Inserter from the W6LVP website (where orders can also be made–pricing identical to eBay):

The Wellbrook Model ALA1530LN-2 and DX Engineering (Pixel/Inlogis) Model RF PRO-1B magnetic loops are both good amplified receive antennas. However, they are both expensive. Shipping the Wellbrook antenna from the UK to the US adds another $100.

Extensive side-by-side testing of the Wellbrook, DX Engineering, and W6LVP receive loops was compiled using simultaneous WSPR signal-to-noise reception reports on all LF, MF, and HF amateur bands. In addition, extensive laboratory bench tests measuring gain, signal-to-noise ratio, and IMD were also performed. Signal-to-noise ratio is important to pull weak signals out of the noise and IMD is important to reject distortion caused by nearby strong transmitters such as AM broadcast stations. In both test regimens, all three antennas performed very well and without significant difference.

The antenna version listed here includes a power inserter for use with receivers or with transceivers that have a separate receive antenna input. If your rig doesn’t have a receive antenna input, check out my antenna with a transmit/receive switch.

If you live in the shadow of one or more high-power AM broadcast transmitters, contact me about a special version just for you. Please contact me at [email protected].

W6LVP amplified receive-only magnetic loop antenna (boy is that mouthful):

The W6LVP mag loop is a complete receive antenna system delivering top-of-the-line performance to amateur radio operators and SWLs – particularly for those with space and/or budget limitations. It is a great complement to vertical or wire transmit antennas. You have a knob to turn up the power but don’t have one to turn up the received S/N.

Ten foot circumference (approximately 1 meter diameter) loop. Small size yields a natural stealth for HOA challenges. The loop is rigid enough to maintain its shape but flexible for portable transport or attic installation.

Includes a low-noise, broadband amplifier covering 2200 (135 kHz) through 10 meters (30 MHz) with no tuning or adjustment. Perfect match for continuous tuning SDR receivers. Great for contesters to quickly check all bands. Greater coverage is possible at reduced performance.

Light-weight antenna structure fabricated from furniture-grade PVC yields a strong but very light antenna weighing only 2 pounds (not including power inserter or power adapter). Great for both portable/camping as well as fixed installations. Light weight and small size make for lower shipping cost – particularly compared to shipping from the UK.

Directly compatible with a low-cost speaker tripod stand (not included) for portable operation.

Compatible with light-duty rotator (recommended) for fixed operation. Loop can be rotated to null interference by up to 30 dB or enhance desired signals.

Includes low-noise linear AC power adapter to generate clean 12 volts for the loop amplifier. Unlike the DX Engineering antenna which requires 24 VAC, power can be easily supplied by 12 volt batteries during portable operation. Reverse polarity and short circuit protection provided by automatically resettable fuse.

Eham reviews are very positive–so far, 5 stars on all six reviews.

I also discovered this short video of W9OY comparing the W6LVP loop to a full size 80 meter vertical (verticals are much more susceptible to noise than loops):

Click here to view on YouTube.

I am very curious if any SWLing Post readers have ever compared the W6LVP loop to the Wellbrook or Pixel Loop antennas.

I actually own the Pixel Loop and might very well purchase, review and compare the W6LVP loop later this year (if time allows).

If you own the W6LVP loop and/or have compared it with the Pixel or Wellbrook, please comment!

Click here to view W6LVP antennas on eBay.

Click here to view the W6LVP website.

Spread the radio love

North American and European medium wave signals into Oxford, UK

2 Replies

Hi there, I’ve been rather preoccupied of late, initially with the brilliant Tecsun PL-310ET and latterly with the even more brilliant Eton Satellit. However, in the background (as always), I’ve been trying to catch transatlantic medium wave DX. My listening schedule is broadly based on shortwave DXing during daylight hours – when I’m not at work of course, typically a Friday afternoon or at weekends – and always with a portable. Evenings usually start off with a tune around the tropical bands, followed by setting up the Elad FDM DUO to run some medium wave spectrum recordings overnight. In the past few days though, my daylight DXing has been bolstered by my NooElec RTL-SDR and ‘Ham it up’ upconverter. I bought the device over a year ago and after some initial exceitement, it quickly became quite obvious that I needed a reciever with a bit more ‘oomph’! However, it’s actually proving very useful to view signals on a spectrum, even when I’m conducting most or all of my listening on a different (i.e. higher performing) receiver. Ultimately, the RTL-SDR is always going to be a compromise, with relatively limited sensitivity, but because by it’s very nature it has excellent selectivity, overall it’s a reasonable performer. My particular RTL-SDR performs quite well if a decent antenna is employed with it, such as a longwire or the Wellbrook ALA1530 active loop.

Anyway, back to the medium wave DX. In the past month or two, I’ve copied a number of stations from North America, with really nice signals, including WRCR Rampano – New York, WFED Federal News Radio – Washington DC, WENE – Endicott and WUNR – Brookline from Newton, Mass. I’ve also recorded a lovely interval signal from RAI Radio 1, Milano and further European signals from Magyar Radio, Budapest and Radio Slovenija 1, from Ljubljana. During the past 18 months or so of DXing, I have been mostly ignoring signals coming into Oxford from the continent. However, that changed a little after I stumbled across the RAI Radio 1 interval signal, which complete with the rather rousing Italian National Anthem, inspired me to dig out some more European DX. I’m actually finding European DX quite rewarding, particularly because it feels new again – not surprising since I haven’t listened to Europeans on medium wave for any length of time since the 1980s. I hope you enjoy the reception videos – embedded video and text links follow below and I wish you all the very best DX.

Click here to watch on YouTube

Click here to watch on youtube

Click here to watch on YouTube

Clint Gouveia is the author of this post and a regular contributor to the SWLing Post. Clint actively publishes videos of his shortwave radio excursions on his YouTube channel: Oxford Shortwave Log. Clint is based in Oxfordshire, England.

Spread the radio love