[Scanner] scanner antenna

[Edmund F Leavitt]

Hi Don,

Nearly all "gain antennas" only provide gain at a relatively narrow range
of freqs.   If you are using a Ham antenna with 10 dB gain, it probably
rolls off to zero gain if you go a few MHz out of its intended range.  
Generally speaking, the better the gain, the narrower range of freqs that
still produce gain.  The only exception that comes to mind is a log
periodic dipole array (LPDA), where it is both broadband, directional,
and exhibits gain in varying degrees depending on its design.  Bandwidth
for an LPDA is typically in the range of several octaves.  Unfortunately,
LPDAs are apt to be expensive.  The one exception to that would be the
traditional TV roof antenna, intended for VHF-Lo to UHF.  With that in
mind, you might consider turning a TV antenna 90° on its boom to make it
vertically polarized and see if it gives you what need.  Other than that,
be prepared to dig fairly deeply in your pocket.

I personally have high regard for the much scorned Discone antenna if you
want omnidirectionality, and gap-free performance over four or more
octaves.   As with any antenna expected to work UHF, don't "cheap out" on
the feedline.  For a 50 foot run, 1/2 hardline is probably ideal.  But if
that's too painful,  the lowest loss braided coaxial cable you can find
should be used.  I would suggest  LMR400,  Belden 9913 or Belden 9913F7.
****************************************************************
Edmund Leavitt                   Ph:    253 582-5034 
Ham / MARS / FEMA:        KA7UKN / AFA5AH / KPS654 
Lakewood, WA                   N 47° 09'   W122° 31'
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On Tue, 17 May 2005 11:18:45 -0500 "Don" <wxfreqrs at cableone.net> writes:
> HI ALL
> looking for the highest gain scanner antenna
> it will be 40 in the air here on MS GULF COAST
> prefer a vertical as i don't have a rotator but will consider yagi 
> type if 
> gain is exceptional over my ham antenna of 10.4 which i am using 
> now
> scanner is bc780xlt
> Don
> SEMPER VIGILIS
> EAGLES  may soar, but weasels don't get sucked into jet engines
> http://www.veteransparty.us/MS01.htm Ms Veterans Party
> http://www.jcmsara.org Ham radio link
> http://myweb.cableone.net/wxfreqrs/  Pascagoula Ms Real Time 
> Observations 
> 
> _______________________________________________
> Scanner mailing list
> Scanner at mailman.qth.net
> http://mailman.qth.net/mailman/listinfo/scanner
> 
> 


****************************************************************
Edmund Leavitt                   Ph:    253 582-5034 
Ham / MARS / FEMA:        KA7UKN / AFA5AH / KPS654 
Lakewood, WA                   N 47° 09'   W122° 31'
****************************************************************