(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

(Tom Bruhns) wrote in message om...

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.


RFSim99 seems to be a good program, but after 2 years of ADS and
how poorly it predicts how the "bench" should react (esp. at 1-2 GHz),
I'll stick to actual prototypes for now.


Slick

Slick

Dr Slick,
Way back in this thread you alluded to antennas as being
transformers. The more I think about that statement the more I see
it as being fact. Anything that involved coupling which all
antennas do can be drawn as a transformer !
Since the thread migrated all over the place did you feel that
the group agreed with that position?
Regards
Art

(Tdonaly) wrote in message ...


Slick,
You're not going to make many points on this or any other newsgroup just by
using rudeness as an argument. You need to read more books, Slick, so
you'll have more to add to a discussion than an attitude. You should also read

Richard's posts very carefully and try to figure out what he's saying before
you
fly off the handle and assume the attitude of an angry, petulant child. You'll
learn something and possibly avoid being made a fool of by some of the more
technically sophisticated members of this newsgroup.
73,
Tom Donaly, KA6RUH


That's a joke, Tom. Because I was asking the questions, and
Richard gave me the attitude FIRST, in addition to clearly NOT adding
to the discussion like Roy has.


Slick

Dr. Slick wrote:
"What`s the definition of "surge impedance" versus regular old
"impedance"?"

Arnold B. Bailey treats this better than anybody I`ve seen. But, there
are many treatments. The regular old impedance of an antenna depends
upon its termination.

Surge impedance of an antenna depends on its conductor`s inductance per
unit length and capacitance per unit length. In the antenna these are
not uniform as they are in a transmission line, and average values have
been found useful.

Best regards, Richard Harrison, KB5WZI