[SixClub] Verticals

[Christopher Boone]

Folks,
forget trying to reuse 11 mtr antennas.....Kenyon, if it does not have 
radials, it is likely a 1/2wave antenna.....thus it has a matching 
network at the bottom to match the HI impedance of the antenna 
(2000ohms) to the 50ohm feedline....this cannot work on 6 without 
redesign...cutting the whip does not work here..

THE ONLY 11m ANTENNA THAT CAN BE CUT and SHORTENED for use on 6 is the 
simple 108inch long 1/4wave ground plane with NO matching elements at 
the feedpoint. Thus cutting the element moves the resonant freq...the 
match for a 1/4wave is 1.2 or so to 1 (a 1/4wave vertical is 36 ohms..if 
you cut the element for min SWR, you are NOT 1/4wavelength long and your 
take off angle of radiation may be WORSE....don't worry about a little 
SWR...and it aint the true indicator of antenna resonance)

Before cutting those exotic CB antennas which won't work on 6, go buy a 
4ft piece of tubing, mount it to an insulator (wood, etc), attach 3 to 
four ground radials (whips, wire, what have you) at a common point, feed 
the vertical from the center of your coax and attach the shield to the 
ground radials...
and there is a simple cost effective 1/4wave gnd plane for 6 FM...

Chris
WB5ITT

Kenyon Lenart wrote:

> Ive got a 2 section 11meter vertical.No Radials. How much do I cut off 
> the top section for 6 meter FM? Can I just use the DiPole formula?
> 
> Kenyon

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