[BC] Two-tower array designed for 990 running on 1030

[Phil Alexander]

On 8 Jul 2005 at 14:36, Thomas G. Osenkowsky wrote:

> >My assumption is that DA designers
> >like the fact that the shorter spcing produces a bit more gain in front of
> >the pattern and a slighlty narrower pattern without sacrificing much in the
> >depth of the minima behind the pattern.
> 
> While short spacings may appear to have the benefit of a slight gain
> over a non-D counterpart, the downsides are high RSS:RMS ratio,
> poor bandwidth and low drive point impedances. The vectors in the
> main lobe do not add up to the total i.e. there is a residual.
> 
> There is no free lunch!

If I could take any spacing, it would usually be 110 to 135 deg unless
it was one of those unusual cases where 180 would work. The common
point curves are so much better, and cranking is a breeze compared
with a short spaced array. But, with the price of land today, who can
blame the owner for trying to make it smaller? Unless you have a 
10 or a 50 kW, you have to be so close in to the population center
for night with most of the NIF levels up where they are today that 
land is at a premium.


Phil Alexander, CSRE, AMD
Broadcast Engineering Services and Technology 
(a Div. of Advanced Parts Corporation) 
Ph. (317) 335-2065   FAX (317) 335-9037





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