[TowerTalk] Phasing verticals and stubs

[Ian White GM3SEK]

Don Havlicek wrote:
>The 'right triangle' system utilizes two verticals per selected 
>direction with the third 'floating'. The 'equilateral triangle' system 
>uses all three verticals simultaneously,

Any triangle system can be used with either two or three elements 
energized - check with ON4UN's book for details. In either case, the 
most practical and versatile system for beam switching is the 
equilateral triangle.

When only two elements at a time are used (the third being 
disconnected), an equilateral triangle gives three directions along the 
sides. With three identical elements and ground-planes, you have easy 
reversal for a total of six directions.

When all three elements are used, usually one is driven with 100% 
current, and the other two are driven at the same phase with about 50% 
current each. The beam directions are off the top or the bottom of the 
triangle (so they are moved around 60deg compared with the two-element 
case). The gain is higher using all three elements, but beam switching 
is much less simple so you may be practically restricted to only three 
directions.

Any right-angled triangle would be less versatile than either of these 
equilateral cases.



-- 
73 from Ian GM3SEK