Antenna Polarity

[Rippey574]

I am trying to figure out how you change the antennas polarity or determine its polarity. Now the definition of polarity I am using is +/- polarity. I am working on my sat scanner and use SatScape to track satellites. Now the satlites have a polarity symble on their names on the screen.
(examples {Oscar III -}, {AO-51 +} )
Now I know if my antennas polarity is wrong the signal is 100 times weaker. I am perty sure that my antenna is a + polarity, I can almost always get a lock on the + polarity satellites.

 

[RadioRon]

Although I am new to this stuff, I had a look at the Satscape forum and over there it was explained that the + and - signs after the name of the satellite indicate whether it is operational (+) or not operational (-). Doesn't seem to have anything to do with polarization.

As far as I can see, most satellites use circular polarization. This means that if you are using a linear polarized earth station antenna (like a vertical monopole, yagi or similar) then you don't have to worry about polarization, but you will always suffer a 3 dB hit to your link budget. The only way to make up the 3 dB is to use a circularly polarized ground antenna and then you have to make sure that you use RHCP (Right hand circular polarization) if that is what the satellite is sending. If you use an antenna with the opposite circular polarization (like LHCP (Left hand ...) in this example) then you will suffer a lot of loss, maybe 20 dB or more.

Like I said, if you are using an antenna that is linearly polarized, as most are, then you shouldn't have to worry about it since circular polarized signals coming from the satellite contain equal amounts of any one linear polarization. No matter which way you twist your one yagi, you will always receive the same power.

Easiest way to determine what polarization your antenna has is to post a photo of the whole antenna (or the whole array if that's what you use) and let us guess.

 

[Rippey574]

LoL, guess I should have read the SatScape form. The antenna I am using is a home brew J-pole.

 

[RadioRon]

I guess you've already figured out that you've got a linear polarized antenna, and its polarization depends on whether its standing straight up or has been blown over by the wind. Anyways, have fun.

 

[Rippey574]

Ya, its linear, I just started sat bouncing, I was reading another guide and I guess it was referring to Horizontal and Vertical Polarizations. Here is a pick of my J pole, hard to see its been painted brown to match tree bark.