hasan schiers wrote:

What would be the simplest matching network to use to produce a flat match.
My primary use would be 80m low angle work at 3.7 and 3.5 Mhz, but also want
to be able to use it (with a tuner, of course) for a local net at 3.97 megs.


EZNEC ver. 3.0

Vertical over real ground 5/28/2005 6:39:29 AM

--------------- SOURCE DATA ---------------

Frequency = 3.71 MHz

Source 1 Voltage = 29.15 V. at 0.61 deg.
Current = 1 A. at 0.0 deg.
Impedance = 29.15 + J 0.308 ohms
Power = 29.15 watts
SWR (50 ohm system) = 1.715 (75 ohm system) = 2.573

Hi hasan, If you don't want to use capacitors in your matching
circuit, just shorten the antenna a couple of feet. That will add some
capacitive reactance at the frequency of interest. Then you can use a
shunt inductor to get a 50 ohm match. What you will really have is an
"L" network with a series cap and shunt inductor. You tune the
capacitor by changing the length of the radiator, and tune the inductor
by adding or removing turns.
An example, if you shorten the antenna until the impedance is around
29-j25 at 3.71mhz, a 2.5uH shunt inductor will give a 50 ohm match.
Gary N4AST