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From: mcovingt@athena.cs.uga.edu (Michael A. Covington)
Newsgroups: sci.electronics
Subject: Re: How to upgrade factory whip antenna
Message-ID: <1991Apr3.161011.1815@athena.cs.uga.edu>
Date: 3 Apr 91 16:10:11 GMT
References: <978@igor.Rational.COM>
Organization: University of Georgia, Athens
Lines: 24

If your FM antenna is a whip, and is 30 inches long and is vertical,
your reception is already about as good as it can be in your location.

There are two kinds of after-market antennas: those with a 75-ohm
coaxial cable, and those with 300-ohm twinlead.

To connect a 75-ohm coaxial one, simply collapse the whip antenna to
minimum size. Then connect the cable as follows:       
  --- inner conductor to the whip;
  --- outer conductor (shield) to system ground, i.e., the outer ring
      of the headphone connector or any audio connector that's convenient.

To connect a 300-ohm twinlead antenna, use a balun (transformer) to convert
its output to 75 ohm coaxial. (Exactly like the little transformers used
on cable TV connections, but backward.)

If you want better FM reception, the main thing you need is *height*.
Propagation is line-of-sight and raising the antenna even a few feet
can make a big difference. 
-- 
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Michael A. Covington | Artificial Intelligence Programs
The University of Georgia  |  Athens, GA 30602   U.S.A.
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