For my station setup it was a requirement to only use one single dish for QO-100 operation.Very familiar are two solutions:a. POTY Antennab. HELIX AntennaI searched for the total antenna gain and both antenna types are nearly equal for me.Difference test between both solutions will follow, but I started with a POTY Antenna.
First Measurements (without dish)
This solution is okay for the first step (rough SWR setup), but for the final setup the dish had high influence to the antenna system, like a refector on a yagi system…
Final Measurements (with dish)
Best measurements shall be done with the dish and directly on the poty device, without additional cable. The cable loss / adapter loss has higher impact on the impedance measurement as on the short wave! Attached some measurements taken with miniVNA Analyzer. Perform for the desired range a new calibration, mandatory!
Minimum is in expacted range…
With the dish, TWO dips are there, but not optimized for desired operating frequency range.
Tuning the POTY Antenna
After some tests with the POTY antenna, I want to optimize antenna matching.Mainly the distance between front plate and rear plate can be modified to tune the antenna. Also additional plastic material can be used.You have to try out…My final results are not perfect, but better than before.
Final measurement / mechanical details of POTY Antenna
The figure below shows my measurements of POTY antenna: