I am now in the final phases of my rotor build, and I am starting to look at antennas.
I have not looked at all the satellite transmission specs, but I am wondering what polarization I should consider.
Am I correct in presuming the VHF antenna would be either Horizontal or Vertically polarized? If so, I would have to switch between them based on the satellite.
Same question about the UHF band - LH or RH polarization?
In an ideal world, I would have 4 antennas and switch between them based on which satellite I am tracking.
Does this sound right? I am aware that a single rotor could handle 2 antennas, but I would have to select an antenna that has one or the other polarization and switch between them or run them through an RF combiner. I had seen someone on the forums who implemented a switch, so I am not so worried about that.
If I select one polarization at each frequency, am I losing the ability to see a couple of satellites or a whole bunch?
Great info on antenna combining and poilarization - thanks.
The big unanswered question is this: Are the satellites that can be monitored by a Satnogs station (UHV of VHF) primarily of one polarization? If I set up a horizontally polarized VHF antenna and a RH circular polarized UHF antenna, will I be able to pick up most/all of the satellites in the Satnogs database?
I’d suggest trying to set up circular polarised antennas on both VHF and UHF. (Right-hand circular is probably best, as that’s the polarisation of many weather sats).
Remember that the relative orientation of a linearly polarised sat with respect to your receiving station will change over the course of a pass. This means the apparent polarisation will change too, and so a fixed polarisation receive antenna will be mis-matched at some point in the pass.
Using a circularly polarised antenna does mean that you always have a 3db loss compared to a perfectly matched linearly polarised antenna, but it also means that you won’t experience strong fading due to bad polarisation mismatch (e.g. when the antennas are 90 degrees apart).