On Thu, 9 Jun 2005 16:30:18 -0400, "Fred W4JLE"
wrote:

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.


Ok, just to reiterate so I know I understand (and you can see if I
don't), If I feed a 20 meter dipole cut for my favorite frequency, I
can feed the radio with exactly 1/2 wave of 450 ohm feedline and it
will match the radio? Of course, coax will make a better match (with
less loss?)

Now, if I understand, the principle of the 130 foot dipole matching
the rig is based on the length of 450 ohm twin-lead. The twin lead is
always 1/2 WL long. The coax and rig are 50 ohms, but according to
the smith chart, the impedance of the various frequencies range from
20 to 100 ohms. This would make me wonder why I don't get the same
impedances at my rig, or at least at my feed point of 50 ohm coax.

Thanks


--
73 for now
Buck
N4PGW