[RFI] Polarity Tests -- Great Work, Wrong Word

[Tom Thompson]

Hi Jim,

Thanks for the correction.  OMG what a mess.  Polarity appeared 
everywhere in my text, in my folder names in my links, in my html 
heading...  I think I got it corrected.  Here is the corrected link:

http://tomthompson.com/radio/AntennaPolarization/Antenna%20Polarization%20Measurements.html

Tom   W0IVJ

On 6/13/2017 12:09 PM, Jim Brown wrote:
> 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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