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Old December 4th 05, 02:25 PM posted to rec.radio.amateur.antenna
Paul Burridge
 
Posts: n/a
Default how to measure antenna impedance ?

On Sat, 03 Dec 2005 21:13:36 -0800, Roy Lewallen
wrote:

As I mentioned in my earlier posting, most people overestimate their
ability to make accurate RF measurements. It's not at all trivial. Be
sure to check your results frequently by measuring known load impedances
close to the values being measured. How do you find the values of those
"known" load impedances? Well, welcome to the world of metrology!


Roy, I've seen your postings hereabouts over the years and you've
always struck me as one of the most knowledgeable posters on this,
*the* most technically-challenging of all hobbies.
I've recently bought a VNA and am going about the laborious process of
setting it up with precisely-cut interconnects to the T/R bridge. Next
thing I need to know is...
Say I have a mica capacitor (for example) that I want to check for its
SRF. How should I mount this component so as to minimize stray L&C
from anything other than the component itself? IOW, what 'platform'
(for want of a better word) do I need to construct to permit accurate
measurements of this cap's RF characteristics in isolation?
Thanks,
Paul
--

"What is now proved was once only imagin'd" - William Blake