at best calibrate at the cable end .... then you see the impedance of the antenna alone ...? not with cable (that may rotate you results in Smith)
dg9bfc Sigi
Am 15.01.2025 07:23 schrieb "Fran?ois via groups.io" <18471@...>:
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I calibrated at the S1 port directly.? Then I connected S1 to the feed
line and subsequently
the antenna. The plane I measured would be where the feed line attaches
to the radio.
** Yes, I understood what you did.
It is not a mistake. You measure the impedance of your antenna, brought
back by your cable. It is the impedance that your TX sees in transmission.
Where it is a mistake is the deduction of saying that the antenna is too
long. You could, through software like SimNEC, find (see) the calculated
impedance of the other end of the cable (antenna side). But:
- You have to know how to use SimNEC which is not obvious
- Know what you are doing
- Assume that the cable is the one you are using
- Know the exact length of the cable
Add a length of cable (Tx side) and you will see that the impedance
brought back changes
--
F1AMM
Fran?ois
-----Message d'origine-----
De la part de David Gerhart
Envoy¨¦ : mercredi 15 janvier 2025 07:12
