"Roy Lewallen" wrote in message
...
Yuri Blanarovich wrote:

What I had in mind is the difference in "capture area" related to
physical size of antenna like rhombic vs. similar gain, say Yagi. It
appears that rhombics perform better than corresponding Yagi thanks to
larger physical size (5 - 10 wave lengths) interacting with the
environment (more like diversity effect?).

That's a commonly believed myth, but myth it is.


Perhaps "myth" based on actual experiences. W6AM had a rhombic farm and
results in contests and comparison with locals using competitive antennas
seem to give it edge over calculations. I had rhombic once also and
experienced exceptional reports. I know it is anecdotal "evidence" but those
who used it, know the difference. Professional installations used them and I
have not seen them replacing it with the "same gain" Yagis.

It seems that rhombics perform better than calculated
gain/capture area figures.

So do EH, CFA, Isotron, Rai-beam, and more other antennas that I can
count. That's because modeling programs just don't account for the magical
effects.


I would not put rhombics in the same category, that is a stretch.
We saw the "infallability" of modeling programs using lumped inductors as
loading elements.

We will have opportunity to do some tests of rhombics farm vs. some
classics soon. It will be interesting to see the results.

Maybe. Even fairly simple RF measurements are very difficult to make with
even modest accuracy. Antenna measurements are more difficult yet.

Roy Lewallen, W7EL

Very simple RF measurement is when comparing two antennas, one hearing the
signals, while another one is not.
One example at VE1ZZ: he has few beverages for Eu. Regular one, phased pair,
staggered pair and the "weird" one terminated on a stainless steel hubcap in
the salt water, very similar to the Regular one. The SS beats all the others
most of the time. They are about the same length ~870 ft, can the modeling
figure out wasaaap?

I am just trying to find excuse for seemingly superb performance of
rhombics, attributing it perhaps to diversity effect by being stretched over
large area. I am not selling any, but have access to about 30 of them over
salt water marsh and will play with them.

73 Yuri, K3BU