EMRFD Message Archive 14149

Message Date From Subject
14149 2017-07-10 04:04:33 joe living Re: requesting information on feeding balanced antenna with a L matc
Interesting topic.

I am not an expert.

Last year I decided to put up a 160 meter dipole fed with real ladder line, not window line. I reviewed a ton of reports on the proper antenna tuner to use to feed this antenna. I wanted matched currents in both lines feeding and dipole to keep RF out of the shack. I finally decided on a dual L network where there is a coil in each feedline with a capacitor shunting either the input or output of the dual L network. This design has a 1:1 current balun on the input side of the tuner and calls for some way of gang tuning both coils.. I tried making one but settled for a commercially built model that was pricey but would handle my amplifier.

As far as I can tell all the other attempts at feeding balanced antennas using baluns, floating T networks, and even the old Matchbox yield at best matched voltages in each line but not matched currents. A dual L network system like the model offered commercially would seem to be the way to go. The others work but you are not really using a balanced antenna system.

Joe W3GW