[isw]

In article ,
Gary A. Edelstein wrote:

On Tue, 22 Aug 2006 12:50:52 -0400, Norman
wrote:

Hi,
I have 2 similar table model FM radios, with similar reception problems. I
connected a homemade folded dipole (made of twin lead) to the 300 ohm
antenna terminals of one and had good results. The other radio has only a
short length of wire as the FM antenna. I tried to increase the length
somewhat but there was no appreciable change. I would like to connect a
folded dipole to it but since it now has only the single wire antenna, no
300 ohm terminals, where would I connect the 2 dipole wires?

The wire is probably 75 ohm.

Actually, probably not; it's probably a high-impedance input. Those can
work quite well with a "short" antenna, something a 75 ohm input cannot
do. The difference lies in whether the input of the receiver wants
signal power (matched impedance), or just signal voltage (high
impedance).

Oddly enough, if the input impedance is "infinite", the signal voltage
(not power) picked up by the antenna is independent of its length.

Isaac