RadioBanter - View Single Post - 50 Ohms "Real Resistive" impedance a Misnomer?

July 17th 03, 12:02 AM

(Dr. Slick) wrote in message . com...
(Tom Bruhns) wrote in message m...

But for ham applications, do you really care about all this? There's
probably not a need to, if you're just trying to get power to an
antenna, but if you care because you simply want to learn how to build
a precision system and make precision measurements, that's fine too.
You should be able to find lots of info on the web about that...try,
for example, to find Hewlett-Packard/Agilent ap notes on RF
measurements and calibrations.

Cheers,
Tom

When you are trying to design a 9 element Chebychev low-pass
filter, it becomes important to test it will a 50 Ohm dummy load that
doesn't drift all over the place at higher frequencies.

RFSim99 lets you easily see how (in)sensitive such a filter is to load
resistance and reactance. And if you're going to use it in a
transmitting (or receiving, for that matter) application, it might be
good to know that, since it may be rather difficult to control either
the load or the source impedance, especially over a wide frequency
range.

Cheers,
Tom