[TowerTalk] Side by Side, Elliptical polarized yagis for 6m?

K7GCO@aol.com K7GCO@aol.com
Wed, 25 Jul 2001 14:40:51 EDT

 In a message dated 7/19/01 2:21:35 PM Pacific Daylight Time, 
ve9aa@nbnet.nb.ca writes: << 
  Hi Everyone,
  Mike VE9AA here.
  Brand spanking new to the list and I am going to fire off a question right
  off the bat.
  Has anyone tried side by side, each slanted 45 degrees, (tops pointing
  towards one another), fed IN-PHASE
  for elliptical polarization? (I don't want RHCP/LHCP)
  I am primarily a 6m DXer so local tropo, EME, etc. usually does not interest
  me much.
  I'm thinking of a pair of the K6STI long 5 elements spaced 5/8wl apart up @
  58' or so.
  Have 5 "other" 6m antennas here, so wanna try something "new".
  Mike VE9AA
  Michael, Coreen & Corey Smith
  (VE9AA,  VE9AAA & Baby)
  271 Smith Rd
  Waterville, NB
  E2V 3V6
 Any polarization coming in that is different than you have, it can be 
effective as the angle of radiation is different if at the same height as the 
other antennas.  If I were to do this I'd model it in Eznec along with all 
the other antennas you have at the same height and see what the major angle 
of radiation is over real ground.  If it's different than the rest it can be 
of some value if you can switch between them on receive.  Are you sure the 
polarization is elliptical with your configuration?

On a blind call you are not sure what the optimum angle is on transmit 
without first making the contact and then running comparisons.  If it is at a 
different height than the rest it could have about the same angle(s) of 
radiation as the rest and be of little value.  Being of the same polarization 
(or mostly) as of what is coming in is always an advantage but it's not 
always constant as polarization shift occurs.  I have a beam with 6 
polarization's and switching between them eliminates about 75% of the QSB 
which is a significant advantage--all the time. 
 If both are at 45 degrees to a vertical masts there will be RF coupling to 
it, distortion to the pattern and degraded performance.  Quads have an 
advantage of bottom feed where the feedline is mostly out of the direct 
antenna field.  With a fiberglass mast you could get 45 degree polarization 
from corner feed and very little coupling to supporting metal members below.
 Horizontal yagis have very little coupling to a vertical tower.  I ran 
patterns with the simulated tower and mast and found horizontally polarized 
Quads with their bottom feed have more coupling to a tower than a yagi.  It 
can be reduced with an insulated coupling(s).  The 2 element tapered quad 
fiberglass elements had less RF absorption to the mast/tower than a 2 element 
with a 8' boom.   K7GCO    

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