[TowerTalk] elevated verticals....radial config.

[Terry Conboy]

According to modeling in EZNEC, as long as the two radials are symmetrical 
(180 degrees apart, same slope), the azimuth and elevation patterns are 
very uniform, and the horizontal radiation cancels quite well in the far field.

I modeled a 40m ground plane made from 33 foot lengths of #12 copper wire 
with the feed at 50 feet over "average" earth and 45 degree sloping 
radials.  The elevation patterns with 2 and 4 radials are nearly 
identical.  There is a very slightly oval azimuth pattern (+/- 0.2 dB) with 
2 radials, with the slight maximum broadside to the radial plane.  The 
maximum of the horizontally polarized signals were down 18 dB from the main 
lobe.

The pattern with 4 radials was omni within 0.01 dB, at all the elevation 
angles I checked (15, 30 & 45 degrees).

Certainly, in the real world, other nearby metal conductors (house wiring, 
gutters, etc.) will modify the pattern.

73, Terry N6RY

At 05:52 PM 2005-06-12, Jim Jarvis wrote:
>If you have a limited number of radials, as in 2,
>you will definitely have favored directions.
>
>In fact, even with 4 or more, you have to consider
>that the mean vertical angle of the lowest lobe will
>vary....being lower where the radials are present, and
>higher in between, as Dale observes, below:
>
>>-0-
>>When I was a kid living in Whittier, CA, I had a roof-mounted 14avq with the
>>requisite pair of radials cut for each band.  The radials were strung out
>>the length of our house roof -- North-South.  I'm sure the years have
>>obscured/warped my perception of what I may have experienced, but it seems
>>like I worked a truckload more stations in the pacific NW/VE7/KL7/JA/UA than
>>to the east and west.
>>
>>dale, kg5u