On 6/30/2015 12:40 PM, Tom W3TDH wrote:

I know that what I am about to say is provocative to some but I still
think it is worth saying. If you look at the way that commercial and
military radios are matched to antennas you will notice that most of
the matching is done as close to the feed point as practical.

Since only the power that actually reaches the antenna can be
radiated I have a hard time seeing the point of matching the
transmitter to the feed line. Matching at the feed line connection
point will prevent damage to the transmitter but if that were the
main objective a dummy load would accomplish that.

When you couple the antenna to the load at the feed point you can
have extremely low losses in the feed line. When you do the matching
at the feed point you will transfer the most energy possible to the
antenna and will get the highest available effective radiated power.
Since the objective is the transfer of the highest practical amount
of power to the antenna the place to do that is at the feed point
were possible.

I do realize that it is often simpler and easier to match at the feed
line connection but I felt obliged to point out that is is not the
most effective place to do the job.

Has it occurred to you that it might be important to match impedance
both at the transmitter and at the antenna? When the feed line is not
impedance matched to the transmitter output the maximum power is not
transferred into the feed line. Then you have already lost power that
can't be recovered by the matching at the antenna even if it is perfect.

Your statements are not really provocative, they are just incomplete
and/or wrong.

--

Rick