[TowerTalk] Conclusion, G5RV vs. Dipole

[K7GCO@aol.com]

In a message dated 10/16/00 9:10:57 AM Pacific Daylight Time, K7GCO writes:

<<  a message dated 10/16/00 5:23:56 AM Pacific Daylight Time, n4kg@juno.com 
writes:
   "4. The G5RV is probably a better antenna for NVIS because of the
  vertical 
  component of the parallel transmission line."   K6HI
  
  HUH?
  
  First, a good transmission line will NOT radiate so there should be 
  NO vertical component.
  
  Second, vertical radiation will be primarily at low angles, 
  NOT what you want for NVIS.
  
  de  Tom  N4KG
   >>
 
Tom: You are right.  There is no radiation from the feedline IF a good balun 
is used for the coax.  Without it there will be some RF Spill over and 
vertical polarization at a low angle.
 
 I also recommend using 300 ohm all the way into a tuner.  However for lowest 
reactive load for balanced tuner on each band, use my "magic length" of 300 
ribbon all the way from the initial 300 ohm length into a balanced tuner.  
Use length = 492/3.562 MHz X VP for the "additional length".  I haven't 
checked the VP of 300 for 30 or so years with a GD Meter so I'm not sure what 
it is.  450 ohm ladder line with a .89 VP can be used or 600 ohm open wire 
line with .98 VP can be used also.  If the tuner has a fair range, the 
antenna can be used on 30,17 & 12M also. You need a GD Meter to check 
feedline length (short out both ends and support 5' off the ground) and for 
many antenna needs.  K7GCO 

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