RadioBanter - View Single Post

February 7th 06, 03:18 PM posted to rec.radio.amateur.antenna

wrote:
Please give me some suggestions about a device, which can/should
preferably remain online like a SWR meter, which shows the unbalance of
an antenna connected to the station via a balanced feeder.

To get a relative indication of unbalance on the feeder, run it thru
a toroidal core with a few turns of wire wound around for a secondary
winding. Recitify the secondary voltage, and read with a DC
voltmeter/microamp meter. If you don't have a toroid big enough to fit
around the feeder (likely if you are using 300 ohm line), it should be
ok to transition to smaller line for an inch or so to go through the
toroid.
You are wanting to read the balance of the antenna. The antenna by
itself can be completely balanced, but when you add the transmission
line, the antenna system can become quite unbalanced. The above
detector will give you a relative indication of feeder unbalance, which
I guess you really want to read.
Gary N4AST