> Could you publish the model you used, including the length
and type of
> feedline you assumed? I'm assuming that you're talking
about out-of -band
> mismatch loss?
>
>> I just ran a quick sweep of a 3el SteppIR model and the
loss in the feedline
>> alone due to mismatch is about 4dB at 1 mHz out and 10dB
at 5 mHz out. Add
>> to that the pattern loss and you're well over 10dB total
out-of-band loss
>> compared to a LPDA. That might not seem like much, but
10dB lower
> >interfering signal is roughly 20dB lower distortion
products. It all adds
>> up.
Why does a non-issue like that matter Jim?
Assuming you don't use a Knight Kit Star Roamer super-regen
who on earth would care if 1MHz signal level was even 50dB
worse?
This reminds me of silly things like claiming reducing
coaxial cable loss improves HF reception, or using a 5kHz
roofing filter to enhance CW reception. What a waste of
time. Virtually 100% of the problem is multiple strong
signals inside the passband of the roofing filter, and noise
floor is set by the noise environment around the antenna and
directivity. Selectivity or gain-bandwidth response of the
antenna is a non-issue. PERIOD.
Even very bad equipment like a TS-2000 or original R4C Drake
would never see any improvement from antenna selectivity.
73 Tom
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