Look into the nanoVNA.
$40 well spent for an antenna analyzer.
Spend a bit more ($60-80) and get a nanoVNA S-A-A V2 that goes to 3GHz and you can check your transponder and ADS-B antennas with confidence too.
(Still have to try the DDRR as comm antenna)
N214FL RV-4 Mazda 13B Renesis First flight 20 Feb 2021
N46AZ RV3-B Mazda 13B EFI -- Bought -- Flying
N993FL RV-3A Mazda 13B NA 575 hours