[Elecraft] K-1 Sensitivity

[James R. Duffey]

Bill - You ask a good question

"What happens to this discussion if we consider using narrowband (eg
High-Q) antennas?"

As long as all the stages in a receiving system are linear, from the antenna
to the earphone (loudspeaker), the frequency response of the entire system
is the frequency response of each individual stage convoluted together. What
this means in plain language is that the narrowest stage will determine the
selectivity of he entire system and hence the bandwidth over which the noise
is integrated. I use 300 kHz for my FL-3 setting on my K-1. For the antenna
to play a role, it would have to have a bandwidth narrower than this. For
the ham bands, most antennas have a significantly higher bandwidth than
this. At 7 MHz, an antenna with a Q of 350 (corresponding to an antenna
loaded with a very good low loss coil) has a bandwidth of 20 kHz, so the
bandwidth is still determined by the receiver. At 160 M, the bandwidth is 5
kHz, and the receiver still determines the bandpass over which the noise is
integrated.

So, for the ham bands at least, the noise received is limited by the
receiver bandwidth, and not by the antenna bandwidth. - Dr. Megacylce
KK6MC/5   
-- 
James R. Duffey KK6MC/5
Cedar Crest, NM   DM65