Villard Loop Antenna

[ChrisSmolinski]

Lex has mentioned this antenna several times. I knew nothing about it, so I did some web searching. It seems the original website that described it is no longer functioning: http://users.erols.com/k3mt/hla/hla.htm

But I was able to find another page with the contents of the original page, as a pdf file: http://www.tsf-radio.org/forum/im/145279k3mt_-_villard_anti-jamming_antenna.pdf

This page describes both the construction and theory. If you have local QRM issues, and/or cannot use an external antenna, this may be something to try.

[Zoidberg]

That PDF describes the Villard perfectly.  It's easy to make from inexpensive materials:

• Scotch tape
• Aluminum foil
• Foam core posterboard

I first learned about it from Joe Carr's SWL receiving antenna handbook around 20 years ago, but never bothered with it until around 2010 or '11 when local RFI/EMI overwhelmed even my trusty fugly loop.  I had almost given up on shortwave by 2013 because local noise was so overwhelming it blots out all but the strongest local AM MW and FM stations.

A couple  of days ago I dug out my Villard loop to redo a video I shot a few years ago, but tore the aluminum foil.  I'll need to start over, but I'm swamped at the moment with home maintenance stuff.

Unfortunately the video I shot a few years ago was on an old Olympus digicam, their first to offer video, and the resolution is so tiny by current standards it's practically useless - something like 200x150!  But the audio did pick up the effectiveness of the loop.

I will say that the Villard loop, as demonstrated in that PDF, will not be effective on the funny bands, or anywhere close to 40m.  That size is optimized for 10 MHz and above.  And believe it or nuts, it is very directional in that range.  Not only does it help null out local RFI, but the signal peak is very sharp.  I was really surprised at how effective it is.

My next project is to make a larger version suitable for the approx. 40m funny band range.  Offhand I'm guessing it will need to be around 3'x3'.  Any larger and it becomes impractical, since it's intended to work best horizontally oriented.

Also, it works best with small portables.  Besides being too large and heavy, I wasn't getting very good results with my Sony ICF-2010, while a smaller older Panasonic portable worked great.

It's so easy to make it's ideal as a traveler's antenna.  But you don't even need to carry it with you.  Just buy the materials wherever you are, make it for that location, then toss it when you're finished.

The main drawback to the basic homebrewed Villard loop is that it's fragile, so it won't last very long.  And it's a kludge to use.  Because it's so sharply directional, and extremely responsive to angle, it works best with the "antenna" supported horizontally on pillows - on the bed, sofa or floor works best.  It would also work on bare ground or a picnic table.  Beach sand would eliminate the need for pillows to tweak the angle.  Fiddle with the angle until you get the strongest signal, then mash and fold the pillow supports to set the angle.

The easiest support I found was a beanbag lap desk.  No need for multiple pillows, just tilt and shift the beans (or styrofoam pellets) to retain the desired angle.

The fragility is another issue.  Thin aluminum foil is easier to use for  the makeshift capacitor, but wears out quicker.  Heavy foil lasts longer but crinkles and thwarts easy sliding.

The ideal capacitor would be a sheet of mylar foil, durable enough to hold up, smooth enough to slide easily, but would need to be conductive on one side.  I'm not sure if such a material exists.

Eventually I plan to build one on a more or less permanent sheet of stiff, lightweight material like thin Masonite, with a styrofoam beanbag back support.  The front surface would have mounts for the portable radio - plastic clips, or maybe Velcro.  But the real trick will be finding the durable capacitive foil.

[ChrisSmolinski]

Lex,

Could the last strip of foil, that you vary in length, be replaced with a variable capacitor, since that is the function? It would be much more robust.

You can get double sized metalized mylar at Amazon: http://www.amazon.com/Earth-Start-Reflective-Mylar-Thick/dp/B00725XBGG and http://www.amazon.com/Hydroponics-Mylar-Reflective-Material-White/dp/B004P4322U

I could not find single sided on Amazon, but I know it is available.  Hmm, this might be one sided: http://www.amazon.com/Mylar-Reflective-White-Material-feet/dp/B004QY05H4

Even if you can only get double sided, you could use an insulating plastic with it.

It looks like those rolls of mylar are more than enough for lots of antennas, so a group buy could always be done, if there's enough interest.

[Zoidberg]

Could the last strip of foil, that you vary in length, be replaced with a variable capacitor, since that is the function? It would be much more robust.

Sure, but then it's an actually good loop that costs a little money, instead of a cheapskate Villard loop.  And you'd miss the middle school science project vibe.   

Also, where would you put the book to separate the tuning capacitor layers?  It'd need to be a very tiny book.

You can get double sized metalized mylar at Amazon: http://www.amazon.com/Earth-Start-Reflective-Mylar-Thick/dp/B00725XBGG and http://www.amazon.com/Hydroponics-Mylar-Reflective-Material-White/dp/B004P4322U

I could not find single sided on Amazon, but I know it is available.  Hmm, this might be one sided: http://www.amazon.com/Mylar-Reflective-White-Material-feet/dp/B004QY05H4

Even if you can only get double sided, you could use an insulating plastic with it.

It looks like those rolls of mylar are more than enough for lots of antennas, so a group buy could always be done, if there's enough interest.

Thanks!  I'll check into those.

[ChrisSmolinski]

Could the last strip of foil, that you vary in length, be replaced with a variable capacitor, since that is the function? It would be much more robust.

Sure, but then it's an actually good loop that costs a little money, instead of a cheapskate Villard loop.  And you'd miss the middle school science project vibe.   

Also, where would you put the book to separate the tuning capacitor layers?  It'd need to be a very tiny book.

I think you could get rid of the book.

Yeah, unfortunately it would probably double the cost of the antenna, although it would last a bit longer.  Hmm.. What about a rotary variable capacitor made with aluminum foil?

[Zoidberg]

What about a rotary variable capacitor made with aluminum foil?

Heeeyyy... how 'bout a paper plate?  A fairly simple hole with the paper plate pinned through the backing board might work.

That would overcome the hassle of using the sliding book tuning cap.  The problem with the sliding book is keeping it in place when the whole Villard rig needs to be tilted to null out local noise and peak the signal.  A simple, lightweight rotating tuning cap would sure solve that problem.  And it would eliminate the main wear point in the entire rig.

[Zoidberg]

I made a quickie repair to my Villard loop last night and a demo video for Radio New Zealand on 9700, which was very fluttery and nearly wiped out by local RFI. Should be a good demo for the loop. I'll try to get it on YouTube tonight.

[Zoidberg]

Okey dokey, here it is...

"Villard noise cancelling shortwave loop antenna demo"

https://www.youtube.com/watch?v=32Hy0RAnkBk

This is just a 5 minute demonstration of the loop in use.  It doesn't illustrate how to make the loop.  See the PDF at the top of this thread for instructions - it's really easy.

This compares reception of Radio New Zealand on 9700 kHz around 0900 UTC this week with fluttery propagation and a painful level of local RFI/EMI.  It was just as noisy outdoors, so the main source of noise isn't just household - it's the entire neighborhood, ranging from street and parking lot lamps to poorly maintained animated billboards and power lines.  It's a lost cause to eliminate RFI/EMI in the infrastructure.  The more pragmatic solution is an antenna that minimizes the problem.

The Villard loop couldn't be easier or cheaper.  The only drawback is it's a kludge to work with.  The horizontal orientation requires room on a bed, table, the floor or ground.

I'm still hoping to make this work with my Palstar R30C, via the illustrated hookup loop in the PDF.  But so far it hasn't worked.  I may need to try different coax and an impedance transformer.  If I can get it working, I can build a larger loop, suspended from the ceiling.  It would still be lightweight and with suspension from large hooks, could be adjusted for tilt/angle.  I'm guessing somewhere between 3' and 6' square would be about right for 40m and below (or is that "above"?).

[ChrisSmolinski]

Thanks for posting the video, Lex.

Are you not able to null out QRM when using the R30C via a pickup loop, or just not getting any/enough signal?

[Zoidberg]

Are you not able to null out QRM when using the R30C via a pickup loop, or just not getting any/enough signal?

Not getting enough signal.  Last time I tried the pickup loop there was no difference between waving the pickup loop around in the air and placing it on the Villard loop.

Not sure whether the pickup loop needs a particular feedline, or whether it should go into the lo-z or hi-z input on the Palstar.  I don't have enough time to dig into the problem right now.

However it did work - somewhat - by connecting some plain wire between the Palstar hi-z antenna input and the foil on the Villard loop.  Basically like running a whip from the Palstar to the Villard loop.  But it didn't demonstrate the same nulls and peaking capability.  And, as with the larger portables like the Sony ICF-2010, the Palstar is too heavy to be practical with this small, lightweight version of the Villard loop.  Running a longer plain wire feedline with the Palstar not sitting on the loop didn't help either - although the Villard was now lighter and easier to manipulate, there was no null/peak effect.

The Joe Carr book demonstrates another Villard loop (apparently Mike Villard's specialty was developing small loops using easily obtainable materials for shortwave reception in difficult situations).  This one is box shaped, vertically oriented, and using strips of sheet metal and a tuning capacitor.  It looks like it would fit nicely inside a window frame.

And I've considered the KR1ST loop to replace my old fugloop.  The fugloop worked on the same principle, but had no tuning capacitor.  I adjusted the diameter and coils of the coax until it was peaked for roughly 40m and left it at that.  But after that old hank of coax broke I discard it and didn't have time to experiment with another loop until recently.

[ChrisSmolinski]

Not getting enough signal.  Last time I tried the pickup loop there was no difference between waving the pickup loop around in the air and placing it on the Villard loop.

Not sure whether the pickup loop needs a particular feedline, or whether it should go into the lo-z or hi-z input on the Palstar.  I don't have enough time to dig into the problem right now.

I have seen MW loop antennas that use a separate pickup loop - you might want to investigate some of those designs? The problem with a pickup loop is they inherently only couple a small amount of the signal to the radio.

However it did work - somewhat - by connecting some plain wire between the Palstar hi-z antenna input and the foil on the Villard loop.  Basically like running a whip from the Palstar to the Villard loop.  But it didn't demonstrate the same nulls and peaking capability.  And, as with the larger portables like the Sony ICF-2010, the Palstar is too heavy to be practical with this small, lightweight version of the Villard loop.  Running a longer plain wire feedline with the Palstar not sitting on the loop didn't help either - although the Villard was now lighter and easier to manipulate, there was no null/peak effect.

It could be that you were either detuning the loop, or your connection between the antenna and radio was itself acting like an antenna?

[Zoidberg]

It could be that you were either detuning the loop, or your connection between the antenna and radio was itself acting like an antenna?

Very likely.  There's some hand/body capacitance with this type of loop.  Handling it by the corner of the foam core backing minimizes  some of that detuning, when using the Villard loop with a small portable on the loop/board itself.

For now I've put the fugloop back up with the Palstar.  Thought I'd thrown away the fugloop after the shield and connector broke on the original version, but I'd forgotten that I'd rebuilt it using newer TV coax.  It was stashed away in a box in the bottom of the closet.  It's really just a shielded magnetic loop, sans tuning capacitor, for MW that happens to work on some HF frequencies.

Trying to use the Palstar this week with random wire and other ordinary antennas reminded me of chasing my tail over this problem several years ago.  It's hopeless due to heavy local noise.  The loop isn't necessarily an ideal solution - it's deaf on some HF frequencies - but it's quiet enough to make monitoring possible by leaving the radio on for hours without going nuts from RFI/EMI static.

I'm still hoping to figure out a tunable loop for the Palstar that behaves like the Villard with the portable (from approx. 9-15 MHz), but which works in the funny bands territory.  So far it's the best performer I've found for this area.

I'm not sure whether a horizontal loop is necessary, but there are definitely advantages to having an articulating loop to help null out the worst local noise.  I've mounted the fugloop on a tripod and while it's a bit too heavy to be stable with the loop horizontal, it will tilt back from vertical significantly and makes a difference in minimizing RFI, although the angle doesn't have much effect on peaking an HF signal.

[jFarley]

Great video, Lex; thanks for posting it!