[Antennas] Matching a Mobile Antenna

Sat, 09 Feb 2002 10:59:45 -0600

Tom,

Normally you want a match from the radio to the transmission
line AND a match from the transmission line to the antenna. 
With coax at 50 or 75 ohms a match at the radio is almost
certain and the match at the antenna is normally done with a
tapped coil at the base of the whip.

If you leave off the matching coil at the base of the whip,
you will have higher losses in the transmission line and
will need an antenna tuner of some type at the radio. 
However, those losses should not amount to much in a mobile
installation with a coax run of probably less than 15 feet. 
The biggest losses in a mobile are in the poor efficiency of
the antenna itself.

Regards,
Frank Kamp
K5DKZ

Tom Bates wrote:
> 
> Greetings to the list...
>  When matching a shortened vertical ( center loaded mobile ), is the antenna
> efficiency ( read effective radiated power ) affected much by the location of
> the matching network ?  I am wondering if a matching network at the base of the
> antenna will have any advantage over an ATU right near the transceiver.  My
> understanding of what W2DU had to say is that it doesn't matter--a match is a
> match anywhere in the system ???
>    Thank you, all.   73,  Tom  AA1NZ
> 
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