I have deliberated over this for years now, at one property and another, and I’ve read lots of books and webpages about many different designs, none of which I have settled on. I realised that I had never as yet asked here, so here goes!
At the student house I share with 3 others (often seemingly more!) in Bangor, N.Wales we have a “garden” (all paved) measuring about 3m x 3m. The house is four storey with the “garden” at basement level (actually our living room) so there is some space to go up and not a lot of space for lateral spread. The garden adjoins similar gardens, but beyond them is surrounded by houses and pubs.
Up until now I have had to stick to 20m PSK on a dipole pinned to the ceiling of my room. If I want to do anything else, I have to cart all my SOTA kit up onto a local high spot called Roman Camp. As you can see, I aint getting much chasing done at this QTH.
My current true love in SOTA is NVIS. I’d really like to be able to get on air on at least 80m, and hopefully 60m, but I just can’t see a way of fitting an antenna into that space. I had thought about these two loop antennas:
I like loops and use them for MF RX stuff that provides myself and a housemate with good winter entertainment, decoding utility stuff while drinking port and eating cheese! Does anyone have any thoughts on TX loops and 80? Can I resonate it for 60m with a different cap or shorting out turns, and get away with it? Is it worth bothering with at all? Should I be looking at designs other than loops?
I’ve also looked at EH antennas. I haven’t built one as I fear that in doing so I might break the magic of a good fairytale. Looks like a fat dipole and a load of common mode currents to me.
Anyhow, any thoughts on how to be QRV on 80/60 from a pocket handkerchief would be most welcome.
I used a loop on 20m 12+ years ago, we had it deployed on a mobile home when we stopped (not whilst driving) and IIRC it was not quite on a par with a 20m dipole for inter-EU working. The advantage was ease of setup compared to stringing wires. I’ve never used one at LF but if QMac sell one then it probably works well enough for the people who by QMac, Codan and Barrett gear.
Have you tried asking the neighbours if you can string up a wire loop between your house and a few others? They may be amenable if you offer them some falling down water in exchange
Thanks Andy. That thing looks amazing, but sadly far too expensive. We’re talking low budget homebrew here!
Neighbours we mostly don’t know, save for Miss Jones who is directly behind us and we very much wish we didn’t know! Students and locals don’t really mix so I think that a ponytailed, bearded twenty-something turning up and asking if he can put a wire across their patch would probably result in a half page article in the local rag
Many, many years ago a student friend of mine used to do remarkably well (mainly on cw) with an 80m bottom loaded mobile whip (G3FIF whip for those old enough to remember). He had it up in the tall loft mounted on a biscuit tin (filled with sand for ballast) with a length of wire fastened to the tin as a sort of counterpoise. He even got away without any TVI !!
Sandpiper aerials do an all-band vertical kit for, if I remember correctly, £38. This is based on a 10 metre fishing pole with two coils, one tapped, and an earth post. You could lean it against the wall and run a wire to something like a water main. At first sight this might be unpromising for NVIS but these loaded verticals put out a lot of cloud-warming signal! I have considered modding one of these for SOTA activations, good earths are hard to come by on a rocky summit but a few radials might work well. Incidentally, I had a word with one of the Sandpiper guys and he reckoned it would tune up OK on 60 metres. I notice also that they do a single band helically wound vertical for 80 metres, too, which would probably cover most of the band without re-tuning.
In reply to G4BLH:
I too have tiny gardens and any type of dipole for 80m is a no no, i have a 67ft wire fed at ground level that goes up over the house. I have various bits of metal buried along with some wire mesh pinned to the lawn with bike spokes. Mother nature has claimed the mesh and it is now invisible. Ok its not ideal for NVIS as its more vertical than anything else but then we dont live in an ideal world! Sean M0GIA
Well, I wasn’t going to go down the vetrical route, but that isn’t too much money to experiment with and you have piqued my interest. Is this:
what you were thinking of? It confuses me a bit, I’m not sure what I need to order! A DIY 10/80 9MTR? I think thats it!
I’m guessing the helical dipole you mention may be the “MINI HF DI-POLES” listed at:
Confusing, but hopeful!
Sean: Yours is a good idea, I had toyed with a similar idea myself. I read about a chap who threw a W3EDP over his house and loved it. The EDP is too big to frape over our house at 85 foot, but 67 might be closer to the mark. I don;t know what I’d do about grounding yet, but where there’s a will…
Thanks all for the suggestions, they are most useful.
73,
Dave M0MYA
[Edit - oops, logged in as Geoff again!]
That’s the one, Dave, probably the extra £10 for the plug-in version is worthwhile, you don’t have to wind the main coil! I checked their site and the helical version is no longer listed, but on the other hand they now list a Top Band vertical that looks quite interesting! They have them on the stall at the big rallies, which saves postage!
No grounding is necessary with an EDP, it tunes against a short counterpoise, 5.18 metres for 80 and 40 (also 60 and 15) 1.98 metres for 14 and 18 megs, none for 24 and 28 megs, but if the main wire is made shorter I would guess that more counterpoise is necessary. Actually on my portable version I no longer have measured counterpoises, but a spool of wire which I wind out until the antenna resonates. This just lies on the ground. The W3EDP used to have a tremendous reputation as a DX machine, when the sunspots get a bit more reliable I will give this a serious try, I quite fancy a SOTA DXCC!
I already use a W3EDP for general /P work - I took mine on a recent trip to the Isle of Canna - it seems to put my 5W to good use. I need to make a new counterpoise as mine was chewed into several bits by sheep and cattle. I use a T-network (MFJ-209) because that’s what I have to hand. People seem to like L or PI match with the W3EDP, but the T seems to be fine. It works great on 80m and 40m. I like the antenna a lot. I took it out on my last activation but WX and time dictated getting a wriggle on so I didn’t have much chance to play on HF, preferring to rob Geoff’s 2m SSB contacts. Maybe I’ll give it a better go this weekend. Its handy because Geoff 2E0BTR can set up VHF on a mast and I can string the W3EDP to the top of it and be 85ft away to avoid “audio QRM”. I’d very much like to use one at Bangor, and I suppose it may be possible with a lot of zig-zagging.
Thanks, Sean. Its an interesting read. Running stuff against actual ground is something I have yet to try.
Brian: I forgot to mention, I did experience some hand capacitance effects while using my W3EDP on Canna. IIRC you use a parallel tuner with yours, perhaps that minimises this effect? There was something else I was supposed to mention, but I have forgotten for now!
I haven’t noticed any hand capacitance effects with my parallel tuner, but that might be because the knobs are about 70 mm in diameter! I certainly get hand capacitance effects using the antenna matching knob on my MFJ-949E tuning my G5RV set up as a doublet, and the knobs on the MFJ are quite small.
Sean, I’m impressed at how you’ve made the best of a difficult location! Here I am with a garden long enough to easily accommodate an 80 metre dipole and I moan because it faces the wrong way, I don’t know I’m born!
It was to do with the counterpoise on the W3EDP. I have heard that you are supposed to run it out parallel with the main radiator in order for it to act like a bit of parallel feedline, much the same as an end fed zep. I always set mine up like this when I can, which I know is contrary to your advice, so I’d be glad to hear your thoughts on the matter. Not having to make it parallel would make an installation at Bangor easier for me.
The only write-up of the antenna that I have is in “Antennas To Go” issued with PW in 2003, where G3BDQ says “The counterpoise will work best when running at right angles to the direction of the main wire, but the antenna will still work reasonably well when it isn’t running in the “correct” direction or even when the counterpoise is bent.” During my experimenting I have found that it makes precious little difference how you run the counterpoise, even lying it on the ground: think of it as a short base loaded antenna, it is only going to radiate a few percent of the total output. I think the ideal would be to have the main wire running horizontally with the tuner up in the air and the counterpoise hanging down so that its small contribution to the radiated power is vertically polarised, resembling the GW0GHF 6 metre antenna, but that is not very practical for SOTA as it would need two poles and an autotuner! I say try it out, you have nothing to lose!
In reply to G8ADD:
Brian i enjoy the challenge this hobby keeps throwing at me, Tom ( M1EYP ) uses a 67ft wire with good results at home, his version uses a wire counterpoise laid on the ground of a similar length. Tom has got a far superior ATU to mine and works 160m - 6m easily on his 67ft inverted L.
I might be wrong, to me the ground is a semi conductor at best and that is different locations often require different approaches i.e. in that article i mention i live on wet ground and we all know how well water conducts electricity. Mineralisation of ground and water content will determine its ability to conduct RF. All in the name of fun! Sean M0GIA
Hi, Sean, another nightowler, I see! Yes, I love the challenges, too. My G5RV will get me contacts on 160 metres to 6 metres with an MFJ-949E, though I wouldn’t say it works brilliantly on 160 (or six, for that matter!)
Water is, of course, a very poor conductor, but salts dissolved out of the ground make all the difference, and the peat on some summits is really very acidic indeed, I think the most acidic pH I ever measured was about 2.9!
Anyway, the bands aren’t brilliant tonight so I am hitting the sack,
Well then. Things have moved on with my attempts to be QRV from my very restricted space student QTH. For a short time I had a W3EDP over the house and one of the Sandpiper 9m verticals in the pocket-handkerchief garden. Unfortunately, I have a particularly “nosy” neighbour, and within a week of erecting the 9m fishing pole in my garden, I had a letter from the council telling me I may require planning persmission! A few days later, a lanning officer was stood in my garden. I demonstrated the fact that it is a fibreglass fishing pole and that I can fully collapse it in under a minute and twenty seconds. I also offered to only raise the pole when I was using it, but to no effect. She was adamant that I required planning permission, and insisted that she had “done a lot of reading” about the matter, however, when pressed she could not give me any legal argument at all. A fortnight later I have yet to hear anything.
However, the EDP is still in place and I think it will remain so - it is very unobtrusive. I goes out of my window, up the wall, over the roof and down the other wall of the house. I am using T network tuner. I have enjoyed some success with this antenna, including working Geoff 2E0BTR from Aconbury Hill WB-024 the other day. It seems to be a better TX than RX antenna. On RX it is very noisy (it is usual to have +20 noise), but received reports are always good. I am considering running it through a 4:1 or 9:1 balun with a DC path to ground to bleed off static. Hopefully this will also “level out” the impedance swings a bit. It would also put the feedpoint outside the building. I should also try my Pi/L match on it. I’d be glad of anyone’s tuppence-worth on this matter.
So there you have it. (Very) Restricted space 80m is possible, if challenging and fraught with hassle!
working Geoff 2E0BTR from Aconbury Hill WB-024 the other day. It
seems to be a better TX than RX antenna. On RX it is very noisy (it
is usual to have +20 noise), but received reports are always good. I
am considering running it through a 4:1 or 9:1 balun with a DC path to
ground to bleed off static. Hopefully this will also “level
out” the impedance swings a bit. It would also put the feedpoint
outside the building. I should also try my Pi/L match on it. I’d be
glad of anyone’s tuppence-worth on this matter.
My background noise with tuned antenna is S0 - S1. This does not include any QRM on specific frequencies and QRN on 80 m and 160 m can peak to S5. The loop is already a short circuit, but needs some kind of matching to the 50 ohms. I am using a lazy solution or ATU for this, but other kind of network could be also thought. Have not been using too much my fixed station these years and been mostly /P as you know.
The background increases a little if I switch on TV (old model) and something can be heard from the laptop screen too. I have ferrites at both ends of the coax to the ATU and the power supply cable for the ATU.
BTW I bought also TVI-Matelstrom-Filter from DX-wire to reduce the QRM from a recording digibox antenna, but did not have time to test it in OH. Probably next Christmas then.
