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Old 05-07-2018, 9:20 PM
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Default 160-20m LOG loop-on-ground

Like jjz, this I love my loops but this time decided to try on that is totally on the ground. RX ONLY.

I don't have room for beverages, and have been down the so-called "snake" on ground antenna before, with unpredictable results. This loop is predictable.

Basically it is a 15-foot square wire loop staked to the ground (that's handy!), fed into a step down transformer, along with a transmisson like choke. I'm having a blast, although sometimes the current low part of the sunspot cycle is drag.

KK5JY goes into much better detail than I can here:

The Loop on Ground Antenna - the "LoG"

I'm using off the shelf stuff, like a common 4:1 balun, and a simple coaxial toroidal choke because that's what I had. You may want to do better than I.

I was skeptical of on ground antennas after my poor experience with the snake. This loop is vastly different and I'm really pleased with it. Now if only the sun would cooperate!
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Old 05-07-2018, 9:36 PM
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Considering that we may be entering what has been termed a Dauber Minimum (something not seen in a very long time), the sun isn't likely to be cooperative any time soon, sadly

Well how about some stats, hertz? Did you do some comparisons on stations with this antenna vs. another? Something like this might be right up the alley, so to speak, of urban folks with small lots that can't fit a big antenna or find a W6LVP loop too expensive. An interesting piece here, for sure

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Old 05-08-2018, 10:56 PM
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Well, it is early days - only had it up for a few days. However it is performing well enough that I switched the feed from a 4:1 balun / choke combo to a 9:1 balun for my 50ohm feedline which incorporates a galvanically isolated transformer - this is supposed to help maintain the somewhat low-down directional pattern. Higher angles you basically have an omnidirectional inverted bowl. The antenna analyzer sees the improvement with the 9:1 / 50z feed, but it will take some time to see if I really needed to go that far.

Because of my limited space, I'm only familiar with small verticals at home. But certainly this is nothing like the Force-12 Yagi up at 70 feet or the full size verticals there.

It may be unfair to compare things so early, but overall it seems similar to going from a full size vertical to a *good* quality mobile / portable vertical installation. There is supposed to be a very low-angle on the low bands too, but suburban noise is kind of hurting me and I haven't been listening that long.

Being totally on ground - and staked down for safety - means that the backyard is still usable / stealth / mowable / safe. One thing that ground mounting did was take me out of the nearby induction zone of a bunch of trash that was making 160 unusable - now I can hear things.

The 15-foot square size is ok for me since I like the wide coverage of 160-20m without having 20m directivity go squirrely. However, for 7mhz / tropical bands / utilities etc lower in frequency, if you had the room to double the size to 30 feet per side, I'd say go for it to improve the lower bands even more.

So really no stats to speak of, and the band conditions make it tough to have an epiphany - other than yes, this is a VERY handy rx-only antenna for those with limited space. Heck, one could even make it even *smaller*, but that will start to put the hurt on 160m.

I gotta hand it to KK5JY for putting this info out there. I never had the room for directional beverages and never even thought of an on-ground loop.
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Old 05-09-2018, 2:27 PM
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This is a fascinating idea! I've been reading up about beverage antennas and BOGs lately. Never considered a ground loop (oops, that didn't sound right) as opposed to the sky loop which I've also been reading. .

For decades I've always read that getting a wire up as high as possible was the best set up. Beverages however seem to have the height of 8-15 feet recommended. The only outdoor antenna I've ever used for any lenght of time was a T2FD from RF Systems which performed very well down to the 90 meter band at a maximim height of about 20' on the top end.

I would love to hear updates regarding the reception you're getting with this LOG.
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Old 05-09-2018, 2:41 PM
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I've had an Eyring ELPA 301A lay on the ground dipole antenna for many years and it works surprisingly well for both transmit and receive. Its a good S unit down from a resonant dipole at 20ft on 40m but it also works all bands from 2 to 30Mhz. Here is some info on the Eyring: Eyring Low Profile Antenna 301A (ELPA 301A)

I'll be camping the the CA desert later this week and might take it with me for testing again.
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Old 05-09-2018, 4:56 PM
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I have posted results here in the past when I've taken my Palstar R30 out to the park and laid around 400' of wire on the ground. Not long enough to be a beverage but long enough to get receive lobes from both the end of the wire and also off the sides.

On MW in the daytime I was able to listen to WHAS out of Louisville, Ky. Clear channel Chicago stations would come in 10 over 9 here in southeast Michigan.

On LW the NBD's really come popping in, and on HF listening to air comms on 8918khz out of New York
would come in easily with an S4 reading. That might not sound great but there is a zero noise floor so the audio just pops right out.
Even on 20 meters an S2 reading is a very listenable signal.

Jim
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Old 05-09-2018, 5:11 PM
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Lot's of stuff works on the ground when one is satisfied with the s/n ratio and directivity. Of course beverages come to mind, and sure enough, even dipoles or random "snakes".

The LOG concept is kind of the opposite of a highly directional beverage. Here, the directivity pattern is more like a vertical, even though layed horizontally on ground.

That can be useful, in addition to being able to lay down a large amount of wire into a confined space for most typical suburban lots. It's a good general-purpose low-band antenna.

Just another tool in our antenna kit...
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Old 05-09-2018, 5:16 PM
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Update - from here in Los Angeles, I'm able to copy all the usual stuff at night ---

Mostly VK / ZL / pacific islands, both on 40 and 20m (about 7-10pm), east-coasters, and of course the usual OTH radar RUDELY jamming the 60m amateur band. Most of these guys are the big-guns with power and directive antennas.

Very similar to my top-loaded mobile antennas.

Of course short-skip at night, say on 75m is of course no problem either.

So yeah, the totally on-ground antenna is working well enough to actually leave staked down in the backyard as a general-purpose low-band (with 20m usable to boot) rx-only antenna.

Kind of a new world to be chasing s/n ratios, and not banging s-meters.
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Old 05-10-2018, 3:54 PM
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Recently tried a 300' wire on the ground antenna for use on the AM BCB for the first time a couple of evenings ago.. Probably cannot be considered a true BOG as it is a bit short. However, it did produce an interesting result. On 1630, KCJJ Iowa City had a good signal in here on the PAR EF-SWL as it usually does here at night. Switching over to the "BOG" (running north-south) KCJJ faded almost completely out and was replaced by WRDW Augusta and KKGM Fort Worth alternately fading in and out with each other. Had heard WRDW from time to time in the past but KKGM was a new one for me. KCJJ would have been off to the side of the wire but the others are south of me and would have been off the end of the wire. So, the antenna did perform as per a Beverage.
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Old 05-12-2018, 3:16 AM
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Sure enough, wires on the ground for rx-only seem to work well enough if you are satisfied with their directivity.

Take that 300 feet of wire, but this time lay it on the ground as a loop - preferably with an impedance transformer (like 9:1 BALun , not an un-un) for 50z coax. Or smaller ratio for 75ohm coax. 4:1 isn't totally ideal but good enough perhaps in some cases to get in the ballpark. Use an isolated winding, or maybe add an isolator shortly after it and now see what happens.

Of course that large a loop means that 20 meters will be totally squirrely in directivity....

I could have wound my own, but for the 9:1 isolated balun I chose a totally overkill RadioWavz B19TX balun. Just prior to that I used a 4:1 MFJ autotransformer followed by a Radiowavz B1 ISOX transformer isolator.

Heh, talk about overkill, but I had that stuff on hand. Waaay more expensive than a few winding in the proper binocular core, but I can run over that stuff on the lawn with a truck.
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Old 05-12-2018, 3:05 PM
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Does a tuner help with the 15x15 foot loop-on-ground antenna?

Not really with my installation, no perceptible difference was noted, other than lower the swr to allow a transmitter to put most of the power into the dirt.

EXCEPT for 160m, where even at this small size, it DID make a noticeable improvement so I will leave it inline just for that band.

Of course this made me disconnect the loop and try to hear any noise or stations coming from the common-mode of my coax alone! No stations or noise were heard (crank it up for this test!) but I'm only using a single 20-foot run outside the shack to the loop. I'm not sharing the loop with another antenna farm on a switch etc etc.

I could make the antenna bigger to be more efficient on 160, but I want to keep the 20m directional pattern, so I'll leave it as is and just use the tuner on 160.

Now if the MUF would only rise above 13mhz, I'd be happy My 10mhz utilities are rockin though..
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Old 05-16-2018, 3:22 PM
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It's a keeper!

I gotta' give thanks to KK5JY for doing all the real analysis, especially the EZnec plots. Without that, I would have had a hard time recognizing what the pattern was.

I'm hearing both low and high-angle (short skip and long haul dx) with it. Unlike a highly directional beverage, the ability to hear both short-skip and dx at the same time can be an issue.

Still, it all depends on the propagation. 20m at noon? Might as well hang it up. Wait a few hours.

At the end of the day it is proof to me that receiver gain is totally sufficient with just the receivers on board amp with NO preamp needed.

Years ago, W1FB (sk) had an article about on-ground non-beverage antennas, including a badly drawn pictorial, and I had written these antennas off. Mostly because I didn't know what directional pattern to expect, and the 20-30db drop in overall level was something I wasn't used to. I had no real idea of what s/n ratio was, other than that bending the s-meter was supposed to be the ideal target. Remember that this was long before one could easily do EZnec like computations for the most part.

So happy that I tried an on-the-ground DIPOLE (only 35 feet total, 17.5 feet each side), and as KK5JY suggested, it had the same overall response as the loop! (pulled the loop out for this test). But, because that dipole ran across major family traffic areas and into the garage, it was only temporary for a night. I have total lawn-space for the loop, so it stays.

UPDATE: never have I heard Lou, EA3JE so loud and clear on 20m. He's doing all the work beaming over the pole straight down the Alaska/West coast corridor. The S-meter isn't moving at all, I hear no short-skip from all the other callers, BUT without moving my S-meter at all, it is like he's in my living room. With my ground-mounted vertical, I'd be struggling with ears bleeding. Wow.

Last edited by hertzian; 05-16-2018 at 5:03 PM..
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Old 05-16-2018, 5:30 PM
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I have an SGC SG-230 on my fence connected to a telescopic 42 ft vertical. Could I just disconnect the vertical and connect the hot lead from the tuner to a large loop on the ground and connect it back to ground to try this?
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Old 05-18-2018, 12:29 AM
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You could try - not sure if the SG-230 will just give up without at least a 9:1 or even 4:1 balun to bring the impedance in the ballpark.

And of course insulated wire, on the ground - not a foot above or even inches, but ON the ground, and no terminals touching the soil either. It's not just for convenience but to force the directional pattern / low(ish) lobes.

The mantra is to make sure that you are not fooling yourself with your feedline and it's possible common-mode contamination. This calls for super choking / isolating. And ideally a galvanically isolated transformer that attaches to the loop proper. But, like I said I used a a 4:1 balun autotransformer and ferrite choke for proof of concept - and that worked well enough for me to move a little bit forward to the ideal. Not sure what effect the SG-230 itself might do to the pattern either. Remember that my tuner on 160 was *after* all the normal install stuff was, and was only to just dig out some really weak cw, not improve the s/n ratio - which is what we're really after.

Also make sure your tuner control wires aren't part of the problem either. So just keep the deviations from the original article in mind. Here, we aren't concerned about resonance, but in your case, this would just serve as a general temporary replacement for a 9:1 isolated balun.

I'm not sure what effect that a nearby fence / vertical will do the loop pattern, so keep that in mind too.

TIP: To see the pattern yourself, you can grab the EZnec-demo version, open the "backyard dipole" example file, and go into the wires section and drop that dipole to about 0.1, (zero-point-one) inches away from ground. Run a FFplot, Use the 2D and 3D models, move the sliders etc. Since the "dog" or on-ground-dipole has nearly the same pattern as the loop, you can get an easy way to see the response of the "log" too.

Give it a shot - but don't disregard it if the deviation from the plan doesn't pan out.
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Old 05-18-2018, 12:55 AM
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Gentle reminder - the "log" or "dog" is not a grounded antenna.

But here's how to go wrong, and why the use of an isolated transformer balun is recommended:

So you try proof of concept with a 4:1 autotransformer type balun that shares a ground. And you choke the heck out of the transmission line. BUT, your station itself is grounded near the shack. In effect, that might totally unbalance the loop on ground, and you have some very weird directivity from basically a lollipop antenna on the ground.

I suppose one could temporarily lift the ground, or run from batteries like I do etc... Heh, just a caution not to throw in the towel if the stuff you have laying around doesn't seem to be working like KK5JY's article says it does.

Tonight - the VK net on 20m is VERY good, clean armchair copy. Still not a single wiggle on the s-meter!
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Old 05-19-2018, 5:34 PM
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Wow - low band aeronauticals heard at night without making my ears bleed!

More experiments: for my 30-foot long "dog" or dipole on ground with nearly the same directional pattern as the 60-foot loop, it seems that an isolated 4:1 balun is doing fine. The 9:1 I'm using with the loop was too much for the dipole. I suppose that makes sense. And of course when I made the dipole much longer than 30 feet total, 20m directivity got a little screwy.

Tweaking the pattern by feeding the loop at a different corner, or moving the whole dipole around is proving harder to determine because of band condition qsb/fading. I'll have to wait for conditions to um, improve. For now, just laying these mostly omni-directional antennas down and feeding them at whatever is convenient seems good enough. The receiver has plenty of gain anyway without preamps.

Kind of getting tired of pulling up the loop to play with the dipole in my limited space, as you really don't want to lay these down over other wires - except maybe at 90 angles yada yadda.

EZnec shows trends, so I followup with physical backyard ventures. Once I chose to use a "Real/mininec" ground, the choice of using a 4:1 balun with the dipole instead of the 9:1 kinda confirms what my ears were telling me. I don't have a truly isolated 4:1 balun, so the LDG 4:1 was put into use, immediately followed by a Radiowavz ISOX galvanically isolated isolator.

(Antenna experts will note that bringing a dipole low to the ground, *lowers* the impedance, which is true, but place it actually on ground, and things change when you are NOT trying to be resonant, but lossy and broadbanded ) !

I have to say that I hung up my HF radios in the closet and didn't know if they would ever make a return. These antennas for me have turned into a hobby saver. Still, the bands can be tough, but it isn't as impossible as it was before. I'm pretty happy with the "log and dog" antenna.
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Old 05-19-2018, 8:52 PM
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Where to go from here now that the basic building blocks of a loop or dipole has proven itself - especially if you are *still* cramped for space?

1) Change the shape slightly to what will fit your situation. Perhaps more of a delta or rectangle - within reason.

2) Don't obsess over resonance! Not necessary with these broadband lossy antennas. Unlike a transmit antenna, these are this way on purpose. Makes life a bit easier actually when all you need to do is turn up the volume just a *little* bit more.

3) Invest in higher quality / lower loss transformers, especially below 3.5mhz. Enlist the aid of your local balun-winding guru or beverage enthusiast. Stick to bal-uns, and not un-un's for this project - preferably isolated. Beware of marketing lingo touting "isolated transformers", which can be a sneaky way of being just a sleeve-balun, and not TRULY galvanically / physically isolated windings. You gotta' check what the real story is.

4) Use lossy linear-loading techniques, even with loops (See G6XN book, etc) Coils on the dirt are not happy. Not so much to change the s/n ratio of the antenna itself, but to provide a lower reactance load to the transformer in use. Always keep things symetrical to try and maintain directional balance. In the case of the dipole-on-ground, perhaps end-loading wires - although if you have that kind of space, you might as well loop it!

Just some ideas for my space-cramped brethren....

Last edited by hertzian; 05-19-2018 at 8:59 PM..
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Old 05-20-2018, 1:58 AM
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Very informative and conclusive post hertzian. Thanks for sharing your methods and findings. Fortunately, i have the room to try this antenna out later this year, i will be happy post how i went.
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Old 05-20-2018, 5:16 PM
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My pleasure - I have to thank Matt, KK5JY for doing the real scientific work first, and being concise and to the point, whereas I'm more or less long winded.

Spent about 4-5 hours listening to VK / ZL stations last night on 20m. All running 1kw, usually into a directive antenna, although the strongest was on a ZS6BKW antenna broadside to the states up at 100 feet. Barefoot ops into a buddipole? No way.

I didn't even think to try Radio Australia on 9.580!

What might be helping is that the opposing corners to the sides of the 9:1 transformer feedpoint of the 60 foot loop, is pointing NE and SW, and seem to have no problem picking up much of the pacific, and the northeast of the states and Canada. Even 40m VK/ZL is not too bad, although to get more serious, I'd probably double that size to 120 feet square.

If one isn't used to it, the most disconcerting thing up front is the 30db drop in both noise and signal right off the bat, although the receiver has plenty of gain normally. And since it is on the ground, local contacts, or direct wave is usually non-existent - along with that type of noise too.

Just another antenna option to play with...

Last edited by hertzian; 05-20-2018 at 5:37 PM..
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Old 05-21-2018, 4:39 PM
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Limited space? Just double it with twinlead! (lamp cord, window-line etc)

Make your loop out of twinlead. At the feedpoint to the transformer, flip one side of the twinlead wires and cross-connect one of the loop wires. Attach the remaining two leads to the transformer. Instant double loop.

While it doesn't enlarge the aperture-area, this might make it a much easier match when the loop itself isn't that large to begin with. Ideally you don't want loops conductors very near each other, so I'm thinking window-line if you could stake it down safely for pets and people. BUT, since we're so lossy to begin with, perhaps zip-cord cross connected to make dual loops would be pretty expedient.

I haven't tested or modeled this to see how it would affect not only the match, but also the directional pattern across the spectrum. But I can't but help to think this would be beneficial at 160m or anyone running in reaaallly cramped spaces like only having an 8-foot square lawn.

Last edited by hertzian; 05-21-2018 at 4:43 PM..
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