For all my activations I only use a 20m long efhw since my first sota. Lately as inverted vee 10m over gnd.
With the good conditions on the higher frequencies, I asked myself whether it would also work satisfactorily on 10m band, for example.
So today I compared a 5m long efhw vertical directly with my usual antenna. Both adapted via a 1:49 tansformator.
Here is the video for the comparison test. Unfortunately not shortened with the conclusion only at the end.
73 Chris
Chris,
The 2 antennas compared have very different radiation properties in this setup, one has a pronounced directivity and the other radiates omnidirectionally.
It would also not be negligible (…) whether the two antennas were attached to the same mast when comparing them.
If you could provide a very rough sketch of the setup (with the relevant length and arrangement of the radiating coax cables), the differences could be illustrated with a simulation.
Of course, antennas have different radiation diagrams. The structure, the ground on the summit, the tree, the feed lines and the other antenna influence each other and should be included in the simulation.
A real challenge.
My approach is different.
With the 20m EFHW inv vee antenna and the KX2 antenna tuner I can work all bands from 80m to 10m. Despite the very jagged radiation pattern on the bands higher than 20m, a vertical solution with omnidirectional characteristics does not perform significantly better, at least in this example.
So I’ll stick with the 20m EFHW inv vee and be qrv on all bands in seconds. Without reconnecting and complex mast construction.
And focus on the qsos.
73 Chris
Chris,
In order not to be misunderstood, the expressed reservation related exclusively to the test procedure used (incomplete definition of the test setup, test signals from unknown directions and distances, subjective assessment of the sum of noise and signal levels) and a very generalized conclusion based on this.
The facts have been known in antenna theory and practice for a long time, at least before SOTA existed. Of course there are many myths about this too, hi.
73 gl ar, Heinz
An antenna field test is always exciting … but unfortunately often only valid for the current test scenario.
Under other conditions, completely different results can be obtained:
For example, a weak antenna may have better reception characteristics, because the actually stronger antenna happens to have a deficiency in the diagram exactly at this received station.
But the test shows general tendencies! And that is what you want. I carry out my tests also in such a way!
73 Armin
Heinz, I agree with you 100%. The theory of wave propagation is well known and extensively described. In addition, we now have affordable measuring equipment.
Nevertheless, there are still myths from the bygone era of amateur radio that are passed on from generation to generation.
I enjoy questioning them and, if necessary, disproving them.
Allow me the following anecdotes: I was newly licensed in 2013 often portable with the FT-817 and had a shortened EFHW (12m total length) with a 1:49 transformer. At qso within DL I explain my antenna. The answer: “It can’t work that way. By the way, your report is 58”
73 Chris
… and motivates me to keep going.
Until our next qso. By the way, while our spontaneous and completely unexpected cw s2s on 10m, you on the Canary Islands, I also had the EFHW inv ve at the start.
73 Chris