[TowerTalk] measuring F/B

[K7GCO@aol.com]

 In a message dated 8/29/00 1:22:55 PM Pacific Daylight Time, 
w8ji@contesting.com writes:
   
  Remember that is ground wave F/B, which is useful for low angle 
  signals but does not necessarily reflect the "working F/B" you see 
  on the air.  (OK)
  
  The major flaw with ground wave measurements is the earth greatly 
  attenuates horizontally polarized signals, while vertically polarized 
  signals have much less attenuation.  Because of that, any feedline 
  radiation or scattering has an exaggerated and unpredictable 
  influence on results.
   ***** The proper design of a feed and matching sytem would eliminate 
that variable and make a legitmate test.  
  73, Tom W8JI
  w8ji@contesting.com
  
 Do you have a source or actual test data for that comparison of polarization 
losses statement that has I confess evaded me somehow.  I'm always eager to 
learn new things?  Or were you thinking something else and "dyslectic 
fingers" typed something else like mine often do when I go too fast.  I've 
also been told, read or informed that at high angles Horizontal polarization 
has far more reflection loss than at low angles and vertical polarization has 
low loss at the high angles and high loss at low angles.  

Vertical polarization has such a "Severe Ground Reflection Conflict" at low 
angles over ground that it acts like horizontal polarization for about 6 
degrees creating a null just like the 180 degree phase shift of horizontal 
polarization does.  It's called the "Persudo Brewster Affect".  Horizontal 
polarization doesn't seem to have any "Ground Reflection Skeletons" in it's 
closet.  Salt water chases the "Dyslectic Bad Spirits of Vertical 
Polarziation" away, it acts "Text Book Normal" as if it was "Liquid Copper" 
and even all those ideal patterns in the text books printed on non-conductive 
paper--are for real.  

Would you believe that vertical polarization can create a pattern so low on 
salt water it kicks up a perceptible Mist--"RF Mist" that is.  You can see 
with special (you guessed it) "Polarized Glasses" the vertical pattern of the 
antenna and it also leaves a white salty pattern on the salt water almost 
like Crop Circles.  Unfortunately it doesn't do this on fresh water.  These 
visual patterns are a great aid to antenna testing.  The glasses can only see 
one polarization at a time and you just have to rotate your head 90 degress 
to see the other or 45 degrees for 45 degree polarization.  There is a 
circularly polarized lens in photography to be compatible with modern range 
finders.  This type of "RF Visual Filter" could be of great aid.  That's an 
absolutely true story.  I just made it up.
 
 Reflected Vertical polarization radiated at the highest angles from a 
vertical is of little interest.  I'm not sure what the ground loss has to do 
with F/B unless the ground is somehow selective to the RF from the front 
and/or rear of the beam for either vertical or horizontal beams properly 
installed.  How does it know what end of the beam it came off of?  Wouldn't 
it attenuate either equally?  Did I read something into your statement that 
wasn't in there?  I didn't try to.  Elaborate.  I've swung enough of both 
beam polarization's with clean patterns to have some feel of this over 40 
years.  Share your data if it has some "Technical Clout and Longevity."    
 
 Some time ago I described a vertically polarized beam I've used for over 40 
years that worked great.  Without even knowing what I had, knew any of the 
details or have seen my data, you reminded me that ground reflection losses 
for vertically polarized beams lowered their performance substantially and 
invalidated my claims as seen in Antenna Software and in actual practice.  I 
never claimed more gain.  It doesn't take much lowering of the angle typical 
with horizontal polarization even with say 3 dB less ground reflection gain, 
to give better results on DX.  So I have to ask--which way is it?  Vertical 
polarization has: 
1.) More or 
2.) Less ground loss than horizontal polarization at the low angels?  
I just "want to be sure" to coin one of your very own phrases coincidentally 
directed toward me? 
 
 If there is stronger ground wave from vertical than horizontal antennas, I'd 
say the typical Ground Reflection Factor Angle for Horizontals is higher than 
for a vertical for the same height therefore the major part of the lobe was 
on it way into space before that of a Vertically polarized wave--rather than 
ground losses.  Around Puget Sound I've seen some very very very long Ground 
Wave over Salt water (actually it's a Salt Water Wave).  Any thoughts on 
that?  Lets wring this out with clear thinking and "Advance the State of the 
Polarization Knowledge Art."  Lets all take a vote!  Which is it?  I'll 
compile the votes.  We can't let this conflict academically continue any 
longer in the year 2000.  K7GCO 

--
FAQ on WWW:               http://www.contesting.com/FAQ/towertalk
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com