Original article from: Wayne Sarosi 
 Reposted by Rob Dennis,Moderator HAM_TECH,for use of the FIDO HAM_TECH echo.
  THIS POST/SERIES NOT TO BE USED IN ANY CDROM COMPILATIONS FOR COMMERCIAL
 SALE WITHOUT EXPRESS WRITTEN PERMISSION OF ORIGINAL AUTHOR(S) OF THIS POST.
               ALL AND ANY COPYRIGHTS RETAINED BY AUTHOR(S).
SUBJECT: Circular Polarized Antenna - part one
 There has been a request for a series on 'CP' antennas. The term 'CP' eluded
me at first as I was not familar with the abriviated designator for circular
polarization. At work, we just use the entire words.
 I'm going to begin this ten part series with the basics.
 After researching CP designs with a few engineers and fellow hams,I found
that they knew very little about the subject. I also found I didn't know 
uite
as much as I thought I did about circular polarization.
 So starting at the begining will help all out.
 First, let's discuss the circular polarized wave.
 There seems to be conflicting standards used by the world of physics and the
IEEE. I found this to be true in four reference manuals including the ARRL
Antenna Handbook. At least it's stated right up front but biased according to
which text you read. We will follow the IEEE/ARRL standard in the following
series for obvious reasons.
 There are two types of circular polarization; right and left.
 All of us agree up to this point. According to the ARRL Antenna Handbook,the
following statement:
 'Polarization Sense is a critical factor, especially in EME work or if the
satellite uses a circular polarized antenna. In physics,clockwise rotation of
an approaching wave is called  "right circular polarization," but the IEEE
standard uses the term "clockwise circular polarization" for a receeding 
ave.
 Amateur terminology follows the IEEE standard, calling clockwise 
olarization
for a receeding wave as right-hand.'
 Confused yet? I read it five times before it sunk in. Physics uses 'right',
IEEE uses 'clockwise',the ARRL follows the IEEE and calls it 'right-hand'.
 Just remember the 'right-hand' or 'clockwise' is for a receeding wave or one
that is going away from you.
 [You have one minute to flap your lips with your finger and read the above
paragraphs again.] ;-)
 Ok,now we know a reference we can base "right-hand circular polarization" 
n.
 Now I have an experiment for you to try.
 Obtain a hard rubber ball from the kids or a neighbor's kid and try this:
-drop the ball with a "right-hand polarization" spin and watch which way the
ball spins as it bounces towards you. You'll find it will spin in the 
pposite
direction [this works great with a super ball].
 This is exactly what happens in EME work. The "right-hand circular 
olarized"
signal returns in the opposite polarity.
 The same holds true for passing satellites using circular polarization.
 An approaching satellite's circular polarized wave will reverse as it 
asses.
 Another quote from the ARRL Antenna Handbook states that the circular
polarized wave and a linear wave are mathmatically special cases of an
elipical wave.
 When the magnitudes are the same and phase angles are 90 degrees in time,we
have circular polarization.
-WS
--- GoldED 2.42.G1219
---------------