In article zUcMe.6912$rR4.2379@trnddc08,
"Dale Parfitt" wrote:

"Telamon" wrote in message
...
In article .com,
wrote:

Hello Group

I have been wondering if it might be an advantage to remotely tune
this active antenna using a varactor? The remote unit uses a 40673
dual gate mosfet followed by a 2N5109 npn vhf/uhf transistor which
feeds a 30 turn bifilar wound 4:1 balun. Then rg58 to the control
unit. The whip is 58"/1473mm in length. Any thoughts on this?

Yes. People have done this to design a tunable antenna so you can do a
Google search on it. The antenna element of the right type is inductive
and the varactor diode capacitance across it can be used to resonate it
at some frequency.

--
Telamon
Ventura, California

A short whip will not be inductive at frequencies below 150 MHz or so. At HF
they are entirely capacitive probes.

He can use an inductor along with the varactor diode for a resonate
circuit, to which the whip can be directly connected.

--
Telamon
Ventura, California