Q: What does polarization mean?
Q: Is the radiation pattern of the horizontal simply flipped 90 degress as opposed to the vertical?
Q: Very few antennea seem to be horizontal polarized and tend to cost quite a bit more. Why are horizontal polarized antennae costlier?
Q: I built a homebrew antenna. How do I find its polarization?
A: Here is an answer from:
http://www.larsenantennas.com/technical/basics.html
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Antenna Polarization
Polarization is defined as the orientation of the electric field of an electromagnetic wave. Polarization is in general described by an ellipse. Two often used special cases of elliptical polarization are linear polarization and circular polarization. The initial polarization of a radio wave is determined by the antenna that launches the waves into space. The environment through which the radio wave passes on its way from the transmit antenna to the receive antenna may cause a change in polarization.
With linear polarization the electric field vector stays in the same plane. In circular polarization the electric field vector appears to be rotating with circular motion about the direction of propagation, making one full turn for each RF cycle. The rotation may be right-hand or left-hand.
Choice of polarization is one of the design choices available to the RF system designer. For example, low frequency (< 1 MHz) vertically polarized radio waves propagate much more successfully near the earth than horizontally polarized radio waves, because horizontally polarized waves will be cancelled out by reflections from the earth. Mobile radio systems waves generally are vertically polarized. TV broadcasting has adopted horizontal polarization as a standard. This choice was made to maximize signal-to-noise ratios. At frequencies above 1 GHz, there is little basis for a choice of horizontal or vertical polarization, although in specific applications, there may be some possible advantage in one or the other. Circular polarization has also been found to be of advantage in some microwave radar applications to minimize the "clutter" echoes received from raindrops, in relation to the echoes from larger targets such as aircraft. Circular polarization can also be used to reduce multipath.
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Basically, the radiation pattern is independent of the polarization. If you take 2 vertically polarized antennae and turn one on its side, you'll receive almost no signal between the two - this is called cross-polarization. If you're having trouble visualizing polarization, think of it in terms of light; it works the same way w/ other electromagnetic radiation such as WiFi. LCD panels work on the principle of polarization, by the way. the dark bits of the screen have the polarization 90 deg off.
The reason the vertically polarized omni antennae tend to be cheaper is that they are usually collinears, which are cheap and easy to make because basically, they are just plastic tubes with some wire inside. A slotted waveguide is an example of a horizontally polarized omni - they are big metal tubes which are machined at close tolerances, so you can see why the materials and labor cost more.
Asked by TheSovereign and rerunn
Answered by lincomatic