[BC] KKGM

[PeterH5322@aol.com]

>In the major lobe of an end fire AM DA the AM ERP can be
>many times the tx power.

Sure, but end-fires are effectively limited to 6 towers, on account of 
the field ratios of the end towers becoming too small to manage, 
practically.

Some examples ...

The theoretical field ratios for 5 towers are:

1, 4, 6, 4 and 1, or

0.167, 0.667, 1.000, 0.667 and 0.167

whereas the theoretical field ratios for 6 towers are:

1, 5, 10, 10, 5 and 1, or

0.100, 0.500, 1.000, 1.000, 0.500 and 0.100


However, consider a 7 tower end-fire:

1, 6, 15, 20, 15, 6 and 1, or

0.050, 0.300, 0.750, 1.0, 0.750, 0.300 and 0.050

I know of a few 7 towers which were proposed, but none which were 
actually built.


A side-fire can obtain greater directivity (that is, a narrower 
aperture), without sacrificing stability, and often using fewer towers.


And, a side-fire can often protect many more stations than can an 
end-fire, and with differing degrees of protection, too, while an in-line 
end-fire, necessarily, must have a symmetrical pattern.