"Jerry Stuckle" wrote in message ...

On 9/27/2015 9:46 PM, Wayne wrote:


"John S" wrote in message ...

On 9/27/2015 1:20 PM, Wayne wrote:


"rickman" wrote in message ...

On 9/27/2015 10:41 AM, kg7fu wrote:

Matching the antenna won't make the Return Loss go away but it will
make
the transmitter happy.

Can you explain this? I thought matching the antenna would *exactly*
make the return loss go away because it would eliminate the mismatch.

Not wanting to put words in his mouth....
I read that to mean that the high SWR between the ATU and the antenna
would remain, but the transmitter would be happy with the SWR on the
transmitter/ATU coax.


# Rick is correct. If the antenna (load) is matched to the line, there is
# no return loss, hence no SWR. The ATU will be adjusted (hopefully) to
# make the transmitter operate properly with the impedance as seen at the
# transmitter end of the line.

# Yes, the SWR due to mismatch of the antenna (load) and line will remain.
# Even if the real part of your load impedance is matched to the line, you
# will still have a high SWR if the reactance remains.

# Does this make sense?

Yes. That's what I was trying to say using SWR instead of return loss.
Return loss numbers get bigger with lower SWR.
For example: SWR 1:1 = infinite return loss.


# Incorrect. Return loss increases with an increased SWR. An SWR of 1:1
# has no return loss because there is no returned signal to lose. 100% of
# the signal is radiated.

Return loss is the difference in dB between the forward power and reflected
power.
Less reflected makes a bigger difference and the return loss goes up.

I did a very quick Google and came up with this page that will calculate
SWR, return loss, and reflection coefficient.
Give it a try with SWR of 3, 2, and 1.

http://cgi.www.telestrian.co.uk/cgi-....co.uk/vswr.pl