Originally Posted by

Ah, the "it works because I made contacts with the following DX"
antenna argument.

This may be an extremely compelling way of measuring performance of an
antenna system if done correctly.

It's certainly the most compelling kind of marketing argument snagging
prospective "magic antenna" buyers, especially those who don't have
another antenna up for comparison. But is there a way to make such an
anecdotal claim and have it mean something?

I'm thinking something along the lines of probability of making contact
with a station with identical equipment, averaged over a very very long
time.

If you know the statistical ionospheric loss for the path, the power
levels involved, and antenna gain (or LOSS) you can calculate such a
thing.

I've heard an argument recently that a particular antenna system must
not be too inefficient because it was able to produce contacts with
stations in Australia and New Zealand. The data below are in the same
category.

How do you know that the RoomCap antenna contacts were not made because
the stations on the OTHER END have much MUCH better antennas?

The dynamic range of signals present on the amateur bands is enormous.
You could have an antenna with a gain of -35dBi and still make regular
contacts. That doesn't mean it's good. How about if we stick to dB
gain relative to some simple reference antenna or the isotropic for
antenna reporting?

...

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