[TenTec] Value of RX Only Antennas

Steve Hunt steve at karinya.net
Tue Oct 1 17:34:19 EDT 2013


I agree!

But it's worth noting that the gain of a beam, referenced to a dipole at 
the same height, varies with take-off angle; so how much louder you will 
be on your beam compared to a dipole in exactly the same position will 
vary depending on what path you are working.

Over real ground you typically only get close to the Free Space dBd 
figure at very low elevation angles; at higher angles the gap closes.

Steve G3TXQ



On 01/10/2013 21:18, Jim Brown wrote:
> The dB reference was for a dipole mounted at exactly the same point as 
> the beam.  The result is particularly useful, because "ground gain" 
> (that is, the addition of the ground reflection to the direct signal) 
> is cancelled out.
>
> I see this as a particularly useful way to present the data -- that 
> is, it answers the question,  "if I replace my dipole with X beam, how 
> much louder will I be?"  And they also answer the question, "how does 
> X beam compare with Y beam under the same conditions?"
>
> 73, Jim K9YC
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