Antenna Polarization

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v     Horizontal vs. Vertical Polarization

There are 2 main types of radiation polarization. (Yes, for those of you more experienced, there is circular polarization, but the main intent of this is a simple, easily understandable format created for new hams.) There is horizontal polarization and there is vertical polarization. Generally speaking, hams commonly use vertical polarization for FM and horizontal polarization on SSB & CW modes in the V/UHF bands. On HF many radio signals will have a mixture of each of the components (horizontal & vertical) arriving at the receiving antenna. This is due to the ionosphere refracting the signal as the ionosphere may be changing. On V/UHF, if you are using the opposite polarization from the transmitting antenna's polarization there is approximately 18 dB of theoretical signal strength difference. Depending on distance, power, height, and other factors, this may mean hearing the station or not hearing them.

On HF, there are hams that make use of each of the polarization in their antennas. They may be able to toggle with an antenna switch to see if one antenna makes an improvement over the other. They may use a diversity reception antenna as well. A diversity reception antenna is basically 2 antennas with different polarization characteristics or physical separation with the signals, fed to the radio as one, to enable the radio receiver to use the signal from the antenna which receives the best at that finite point in time. A received signal may shift back and forth between both polarizations in one transmission.

For those of you new hams, one usage for circular polarization is for satellite communications. There is left-handed and right-handed circular polarization depending on the direction the radio signal rotates. Think clockwise and counter-clockwise. They also are not compatible with one another as there will again be a loss of signal strength due to cross polarization.

Some hams purposely use the opposite polarization when RDF'ing (Radio Direction Finding). They do this to attenuate (decrease) the desired signal they are trying to locate when they get closer to the source.

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