Thanks for the great work, but you're using the wrong word to describe
it. The correct word is "polarization," which describes the orientation
of a field in 3-dimensional space. We most often control the
polarization of a field by the orientation of the antenna that produces it.
"Polarity" is the positive or negative sense of the waveform. We change
polarity by reversing the pair of wires carrying a signal, or by passing
it through an inverting gain stage. Historically that has WRONGLY been
called "phase." It is NOT phase -- phase is a continuously variable
function and is measured in degrees.
The effects of phase and polarity are VERY different. Phase varies with
frequency, time, and the nature of the electrical circuit (including
antennas) that carry a signal. Phase is defined for a single frequency.
If, for example, we add a length of line to provide a 180 degree phase
shift, the phase shift is different at every frequency. If, however, we
reverse the sense of the signal, the result is that the two signals
cancel at ALL frequencies (provided that the antenna doesn't also modify
the phase, which it often does).
73, Jim K9YC
On Tue,6/13/2017 10:48 AM, Tom Thompson wrote:
Some of you have mentioned in the past about using a tuned loop for
tracking RFI. A question has sometimes arose about the direction of
the null of the loop. Larry Benko, W0QE, and I did some polarity
tests using various orientations of both the transmitting short dipole
and a receiving loop and a receiving short dipole. The results are
shown here:
http://tomthompson.com/radio/Antenna_Polarity/Antenna%20Polarity%20Measurements.html
73, Tom W0IVJ
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