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Old September 13th 06, 07:18 PM posted to rec.radio.amateur.antenna
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First recorded activity by RadioBanter: Aug 2006
Posts: 106
Default Antenna Theory

Hello Felix,

Reading your text, I also get a somewhat unpleasant feeling.

As I mentioned in my first contribution, A good GSO is not a
representative figure for efficiency, because the difference between
10% and 100% radiated power is 10 dB.

I am very curious to know your test setup for assessing efficiency. For
me efficiency is ratio between radiated output and input. Matching
networks are considered part of the antenna.

At low frequency, determining efficiency is difficult. You probably
must hire a helicopter to determine the 3D radiation pattern, or you
must rely on "traditional antenna knowledge".

In some cases the efficiency may appear to be higher (based on loss
measurements). If your antenna is close to a structure that has
reasonable coupling to your antenna, It may act as a re-radiator (or
absorber).

I like people that don't follow straight paths; many times it resulted
in better products or better understanding. However, when you claim a
certain efficiency, you should fully state how you measured efficiency
and under what circumstances to enable review by others.

I am a little bit skeptical to efficiency claims, especially when I
have to pay in advance. I was professionally involved in measurements
of very small UHF antennas with wide band, high efficiency
characteristics. In most cases the measurements against standard
antennas did not show the characteristics claimed.

I believe you should give more details about your antenna (mechanical
and electrical).

Best Regards,


Wim
PA3DJS

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