[TowerTalk] Vee beams?

[Tom Rauch]

> When a VEE BEAM in terminated
> This basically removes the REAR LOBE -
> Does it affect the forward GAIN?

There is not much change to the forward lobe. A better way to 
make the antenna unidirectional is to place a V behind a V with 1/8 
to 1/4 wl spacing, and phase them. Then you will gain around 3 dB. 
 
> Does sloping the VEE beam legs down 
> so the ends are near the ground - help or hinder
> radiation at low angles???

It generally hurts overall performance, including low angle performance.
 
> One broadcast engineer told me he liked to 
> terminate VEE BEAMS with 800 ohms NON INDUCTIVE.
> Either by connected the elevated VEE beam legs
> with a wire with 800 ohms in center OR
> terminating  the sloping ends with 400 ohms each to ground
> rods and still connecting the rods with wire - so performance
> would be independent of changing ground conductance.

Anything you do will probably have some problems. V's are not 
easy to terminate.
 
> This individual also liked legs 3.3 time 1/2 wavelength
> if termination was used as very effective ( for gain ).
> This seems kind of short to me?

Gain peaks about 3.3 to 4 WL per leg (not half-wavelengths) 
according to actual measurements, and that is for a V mounted 1/3 
of its leg length above ground or higher. It is virtually impossible to 
force enough current out on the wire beyond that point to improve 
gain with additional length, and at lower heights losses will 
increase over normal soil making the useful length shorter.
 
> Any feedback on VEE BEAMS would be Appreciated

I looked at them because I have a very tall tower and lots of empty  
pasture to string wires across. They don't seem to model that well, 
so I never installed them.

If anyone has modelled some V's that look good for gain on any 
band, please let me know the dimensions!! I'd still like to try one 
myself, but I want some assurance it will be better than a small 
yagi.

Maybe I missed something in my research.
73, Tom W8JI
w8ji@contesting.com

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