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How much better is a SOTA Summit than my home location?

I was wondering what sort of improvement I get on transmit from being on a hilltop site compared to my home location. I did an experiment yesterday that indicated that the difference was 7 dB on 20 m (7 dB = a power increase x 5). Without doing more experiments it’s hard to say if this was related to being on a hilltop or simply being on a more open site.

Details here:

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Altitude not amplitude!

This is interesting Richard as a “direct” comparison of locations. I would say however that your mini-loop in the garden would be screened by the surrounding buildings and hence it is not a fair comparison.

Normally a home station antenna is better than we can manage to take with us to a summit and would be at least partially clear of surrounding buildings.

I think the lower noise level from the portable site is probably as important as the clear way for the signal to get out. Were you only able do transmt comparisons or did you mange receive ones as well? The latter is difficult unless two people are doing the tests at the same time at the two sites because of propagation variations.

There are several SOTA chasers who can ONLY chase from portable locations (because of restrictions or interference at the home QTH) and their signals are often some of the stronger ones on the bands!

73 Ed.

Out in open away from man made noises and higher altitude.
Makes big difference, less QRN from man made noises, closer to ionosphere.
Especially on VHF.

Better scenery usually too and fresher air.

karl

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On transmit?

“only change one factor” - Would that mean all the houses would need to be replicated at the portable location then? So that only one factor has changed (e.g. height).

Perhaps I could have chosen a less hard word than “fair” what I was trying to say is that a home QTH antenna would not normally be an antenna shielded to the side by one or more structures.

I guess in short what I am saying is that it’s difficult to get a “real-life” comparison. Despite that - I experience the same effect that I can hear (and therefore have a chance to work) more from a summit with a simple, low antenna than I can from home with a more sophisticated and higher antenna. My home QTH is in a relatively rural location, so I don’t suffer the electrical interference that I would if I lived in a big city and still it’s better to go out portable.

Ed.

No; the test is (as far as possible) a fair one as described. You are suggesting a different test. Nothing wrong with that of course but it’s not the test that I did.

I think a second stage to the experiment would be moving the antenna about the hilltop as a slope can assist the performance of the antenna.

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Thanks for the test! While some may argue that we cant publish a “Nature” paper out of the testing it is indeed very helpful for the average reader (at least… I believe its very good).

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Yes and thanks for doing it.

I think we’ve all “thought” this but it’s good to get a real test done.

73 Ed.

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Although I haven’t done that kind of test,

I do know that I get more ‘dx’ from SOTA summits. But then I live at Robin Hood’s Bay. Not at the bottom of the village, but at the top, and my aerial, one of Richard’s linked dipoles, has a max height a little higher than the guttering.
On one side of our house we have a church and on the other side a Georgian building right next to the other end of the aerial. But I’ve still worked Israel and the states from home using a max of 10 watts using CW - my only mode…
David M6GYU

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