measuring cable loss
On Aug 14, 2:22 pm, (J. B. Wood) wrote:
In article , wrote:
J. B. Wood wrote:
The challenge here is, given a transmission line of certain physical
length, to find a measurable value at the operating frequency(s). An RF
signal source with a surplus (but in proper operating order) General Radio
(Genrad) impedance bridge is good for this type of measurement. Keep in
mind that any coupling from the line to nearby structures will affect the
measurement. Sincerely, and 73s from N4GGO,
Even more of a challenge might be getting that impedance bridge to work
at 1 GHz...grin
Hello, and I must have had a senior moment. Forgot what freq the OP was
interested in. Too many years spent making measurements in the 2-30 MHz
band I guess ;-) Of course now we're looking at a vector network analyzer
to make the measurement (not something most Hams have in the shack). I
wonder if MFJ has anything? Sincerely,
John Wood (Code 5550) e-mail:
Naval Research Laboratory
4555 Overlook Avenue, SW
Washington, DC 20375-5337
Later on in the thread, the OP said he has an Agilent network
analyzer, presumably a VNA, and an HP power meter. Certainly the VNA,
connected to the feed end with the tower end open or shorted, swept
over a fairly narrow range (since he has 200 feet of line) around
1GHz, should tell him enough to characterize the impedance and the
loss. He indicated that he's happy with that solution, some time back
in the thread.
Cheers,
Tom
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