You can't match a 300 ohm antenna with 300 ohm line. A matching section
relies on SWR (read reflections) to match.

once matched, any impeadence feed line may be used from the matched point as
long as it is an electrical half wavelength or multiple at the frequency of
interest.

The only difference will be the SWR on the line. Your rig would still see
the SWR ar the match point.

Given an antenna that has 50 Ohms +J0, feed it with 50 ohm line and the swr
for the system is 1:1, substitute a 1/2 wave of 450 ohm line and the antenna
and the rig are both at 50 ohms. The SWR on the feedline is 450/50 or 9:1.

Look at the half wave of feedline as two back to back 1/4 wave matching
sections. The SWR on the feedline is of no consequece as the losses are so
low as not to have a practical effect.


"Buck" wrote in message
...
I am a little confused, so bare with me.....

I put up an antenna with 50 ohm of impedance. I feed it with any
length of 300 ohm feed less than 1/2 L. Then I run 1/2 L of 50 ohm
feed to the radio and I have the 50 ohm match?

similar:

I put up a 300 ohm antenna. I feed it with 300 ohm twin lead for less
than 1/2 L and 1/2 L of 50 ohm feedline. Is this a 50 ohm match?

(L=Lamda)

Thanks
Buck





On Thu, 9 Jun 2005 00:27:26 -0400, "Fred W4JLE"
wrote:

No buck, the line is always longer than 1/2 wave. It is a matching
section
from what is at the antenna to 50 ohms, and then 1/2 wave from that
point.

"Buck" wrote in message
.. .
Pardon me while I learn from this discussion.

The 450 ohm antenna is designed to be tuned by using exactly 1/2
electrical wave lengths to match both the transmitter and antenna.
This should mean that any differing feedline should work equally as
well (except for the losses) if I am correct....




On Tue, 7 Jun 2005 18:02:43 -0400, "Fred W4JLE"
wrote:

I feed it with an electrical 1/2 wave length of exactly 450 Ohm
feedline.
The 50 Ohms from my antenna is repeated at the other end of the
feedline.
An
SWR bridge calibrated for 50 Ohms and my rig see 1:1.

--
73 for now
Buck
N4PGW


--
73 for now
Buck
N4PGW