On Fri, 3 Mar 2000, Matt Taylor wrote:
>
> In my anechoic chamber, I measure the performance of my horn using a
> network analyzer. That network analyzer's impedance is fixed at 50
> ohms.
But is it really? How can one know how the power output of any signal
source varies with load impedance? Different signal generators and
transmitters may vary widely in this regard. If the definition of gain
includes these effects, then the gain of the antenna will depend on
the kind of transmitter connected to it.
> I cannot complex conjugate match the antenna for each frequency
> point. I could measure VSWR, and then back out the impedance
> mismatch loss from the gain mathematically, but the fact is that no
> one I know does this.
Nevertheless, I feel that publishing VSWR curves vs frequency for any
antenna is important.
> They report what is currently defined as "realized gain", i.e. the
> gain including mismatch loss. Current industry practice reports
> realized gain, but they call it "gain". It is not in synch with the
> current IEEE definition.
I am not aware of that industry practice, but if it is true, then it
seems that people are trying to oversimplify the situation.
Bob
Robert S. Dixon
Chief Research Engineer | Voice 614-292-1638
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and
Senior Systems Developer/Engineer | Voice 614-728-8100 X232
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| Email rdixon_at_oar.net
Received on Wed Mar 08 2000 - 03:21:22 EST
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