WSRO Power Boost

[Dale H. Cook]

At 08:54 PM 7/14/2012, Garrett Wollman wrote:

>The most common configuration for a
>two-tower DA generates a cardioid pattern, with a null in one
>direction along the axis and (perforce) the maximum in the opposite
>direction.

I would suggest that, based on 30+ years as a DA CE, most common is the modified cardioid, with a minor lobe flanked by two nulls, all opposite the major lobe. A pure cardioid provides best protection for other stations only in or near the null. In a modified cardioid the spacing between the nulls can be varied, but in general the farther apart the nulls are the more prominent the minor lobe is. They can provide protection of varying degrees in multiple directions on the back side of the pattern. I have seen a number of modified cardioids in my career, and no true cardioids, although one has spacing, phasing, and ratio of 90, -90, .6, with the nulls only about ten degrees apart and the minor lobe barely discernable. It essentially behaves as a pattern with a broad null having about 25% of the peak E field of the major lobe.

Dale H. Cook, Market Chief Engineer, Centennial Broadcasting, Roanoke/Lynchburg, VA
http://plymouthcolony.net/starcityeng/index.html