This weekend I will be hiking with a group of 30 people and will try to activate SOTA during some photo/snack break (30 minutes). Faster I deploy / pack the antenna, more time for QSOs.
From your experience, what antenna is faster to deploy ? vertical, EFHW, linked dipole ?
Probably won’t have any trees and will carry my 7m fishing pole with me.
If you make yourself a mono-band gp vertical then it’ll take about as long as it takes you to get the pole up, because all the pegs it needs are also the guying pegs for the pole. You’d have to pick your band, though, and it’ll be tricky to use bands below 17 metres with a 7 metre pole.
An EFHW will probably need one extra peg, and a dipole will need a couple of extra pegs, so they’ll take slightly longer to set up…
I’m sure other folk will have better ideas. Good luck. 73, Rick M0LEP
In my opinion the GP antenna made with your 7m fishing pole and one wire as a counterpoise to be layed on ground should give you good enough performance and will be the fastest to erect and deploy.
In the absence of trees I’d recommend you to have one of these with you. It costs 5 € at Decathlon and weights not much:
I also use a GP made with a 7m fishing pole and it works very well on 12m, as such legth is a 5/8 wave. On 30m it’s 1/4 wave. On 20m is 1/3 wave which I don’t think it’s the best but it works fine.
I rarely use it on 40m but it works fine on that band.
I very rarely use it on 15 or 10m so can’t say now how it works.
I usually have troubles to tune for low SWR on 17m, so I don’t try it much.
Best 73 de Guru - EA2IF
I have no ATU, so I need a matched antenna with a SWR better than 2:1.
@EA2IF: what is the name of that item ? Just came from Decathlon a few hours ago, and don’t remember seeing something similar. The GP antenna with counterpoise on the ground can get a good SWR? doesn’t depend on the ground type ?
In the Spanish page I’ve looked up, they call it “Pica - soporte de caña de pescar” which I’d translate into English as “Pike - fishing rod support”
They sell it for 3,99 € now.
If you don’t have an ATU, then I think you should adjust the vertical wire length and cut the counterpoise to a 1/4 lambda in order to get it adjusted to one band.
You may wish to try adjusting to 12m as the 7m long antenna will make a 5/8 lambda, which should give you a good gain of 3,5dB aprox.
If SWR changes or not with the ground below, I don’t know really, as I always have with me the ATU, which to me is a must in the activators rucksack.
Good luck with your mountaneering and activations.
Best 73 de Guru - EA2IF
[quote=“EA2IF, post:4, topic:9787”]I usually have troubles to tune[/quote]I get around that one by having five different GP verticals, one for each of 10, 12, 15, 17 and 20 metres. The one for 20 metres only fits on my 9 metre pole. The others also work passably on my 6 metre pole, though the 17 metres one is happier on the 9 metre pole. Of course, that way I have to change antenna to change band, which is tedious.
I just make sure that all of them hang with their feedpoint at the same height, and have cords from their elevated radials so that the combined length is the same on all of them, and also the same distance from the pole as the pole’s lower guy lines. Here’s one of them on a 6 metre pole (which doesn’t quite get the radials to 45 degrees).
Very similar with my antenna. I use 4 radials instead of 3 that are also used as guy to anchor antenna. The radial angle isn’t 45 because of only 7m pole, but Mmana-gal and real antenna get swr under 1.5:1 .
For wire i use some Cu wires from UTP Cat5 eyhernet cable. Can’t find a better, thin/light cable
In ARRL’s "Wire Antenna Classics, page 8-13 there is a “Four-band ‘Tree’ Antenna” which is adaptable for SOTA. Basically it is three parallel vertical radiators with a common radial system, the 40-metre radiator working on 15 metres. Following the general idea in the article you could make a version for any selection of bands. This way you would not have to change antennas to change bands.
It is simple, with three parallel radiators cut for 10, 20, and 40 meters. The diagram shows the 40m vertical as an inverted-L.
For two bands, you could use window line for the stretch where the two elements are in parallel, then add on wire for the longer element. The 15/40 meter trick would still work to get three bands, of course.
If you have a wide-range tuner, a vertical for 20m is roughly 5/8 wave for 17m, which should work well.
For radials, two resonant radials work nearly as well as three and even one radial works pretty well. That gives a bit of directionality towards the single radial. Running one radial per band would be enough for many purposes.
[quote=“K6WRU, post:15, topic:9787”]even one radial works pretty well[/quote]By that stage you’re pretty much using a (more or less) vertical dipole
I went with the mono-band gp vertical antennas because they were an easy educational exercise to construct, they’re simple to put up and take down, and, so long as I carry more than one I have a fallback antenna if one gets broken. Of course, it’s usually the pole (or something else you’re only carrying one of) that fails…
I’ve found it’s worth looking for telescopic flag poles rather than telescopic fishing poles, as the fishing poles are often too flexible near the tip.
Here on the East coast of VK 40 m is the band of choice for a quick activation. Next most useful if further away from the Sydney-Canberra-Melbourn- Adelaide line is 20 m. However 30 m can fill in some holes in coverage. Only if conditions are very good is it worth worrying about higher bands over here. Our nearest dx is 2,500 km away but most is 12,000 to 18,000 km away via short path.
I use a 40/30/20 m croclink dipole (link dipole using crocodile clips) and support it and its thin coax from various telescopic fibre glass poles from 4 to 10 m long. I use a stake in the ground for the pole and two pegs for the ends although sometimes tree branches and rocks have been used instead. It takes 10 minutes to put up with most of the time spent unwinding the wire and feeder. Dropping the pole section by section allows for a fast band change. I’ve found that, up to the stage where the mast splits due to extreme wind, no guys are required. I do sometimes align the dipole so it is end on to the wind and the stake is also aligned for max strength. They are a small section of arc of a tube cut length ways, so not flat but not a quadrant in enclosed angle. I have a steel stake with rings and aluminium stakes with velcro ties. There are always three masts ready to go in the garage. The stakes mean I am independent of trig points supports etc. I carry a small 300 g hammer to drive the pegs into hard ground and a piece of wood to avoid damaging the top of the stake when bashing away with the little hammer.
Tuned doublets with 7.2 m per side or 14.4 m per side fed wit 300 ohm line and a balanced ATU will give all bands from 40 m to 6 m with QSY as fast as you can tune the ATU. Some of us use these over here.
I’ve also used a G5RV, OCFD, EFW and 1/4 W verticals. The croclink dipole is still my preference for ease of erection and efficiency on 3 bands. I prefer to use an ATU to be kind to the PA but have had a number of activations without the tuner and no smoke was seen.
Situation is a bit different here in YO.
Most of my chasers are DL, EA, G/M which are fine for 20m. Not many chasers close by in YO, HA, LZ, so I will be better with 20m than 40m.
When I have time it will be nice to activate multiband and try some DX in USA or Australia, but this weekend time on summit will be limited, so I will just activate on 20m and hope to have time to work every chaser I can hear.
Quick setup will be a linked dipole trimmed for 20m and with a few m of string on each end; no ATU.
One helper holds pole; peg one guy (only) downwind.
You hold pole, sending one helper with each end of the dipole to form a shallow V upwind and peg down ends of string.
Works fine Force 4 wind and below; needs 3 guys in stronger wind.
I use this setup with a 60/40/20 dipole; erecting single handed takes longer walking to-and-fro to the ends.