you should albsoutely calibrate on cable end and use one as short as it is practical (just a few inches would be best!!)
only THEN you have exact values to type into simsmith .. then calculate parts .. solder them in and THEN measure AGAIN ...
(does the transmitter have exctly 50 ohms or is the matching also to transform the trx outputs impedance to antenna impedance???)
just thinking
dg9bfc sigi
Am 24.02.2025 um 17:32 schrieb Nico via groups.io:
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John,
Thanks once again for the precious advices. As I’ve put the antenna exactly as I t has been manufactured, could I simply populate the matching network instead of stretching the spirals ? C-L-C network is planned on the pcb, it only misses the parts. I’ve installed simsmith software. Once I’ve put the values from the vna, I will be ready to order the correct caps and inductor to match.
I measured my ground plane yesterday night after posting and it does not have exactly the same size as provided in the data sheet. Mine is a little bit wider and shorter. I would suspect that does not help.
If I want to give it a try and stretch or squeeze the spacing, which direction will increase or decrease the résonnant frequency ?
Thanks,
Nicolas
