[BC] High Gain vs Low Gain Antennas

[Richard Fry]

> Wow... so the better signal pattern is the 6-bay... but at ~1.5-2 miles
> from the tower, you have the equivalent signal as 53 miles away!
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In theory the relative field in all of those nulls goes to zero.  The plot 
doesn't show that because the calculations were done at 0.1° degree 
intervals, which didn't happen to capture the zero values.

In practice the nulls measured/received near the ground are to some extent 
filled by reflections, so probably they wouldn't go to zero anyway. And they 
probably won't occur at the calculated distances either, because of the 
affect of the tower on the theoretical, free-space elevation pattern of the 
array.  As you noticed, there can be some "multipath distortion" in the 
nulls, wherever they land.

The 6-bay in this comparison generally has a better signal close to the 
tower, but is it really important to generate fields of nearly 300 mV/m in 
that area?  Receivers don't need that much, and such high fields can 
cause/aggravate blanketing problems.

Over the huge majority of the coverage area these two antennas would give 
equal performance, if they really had the elevation patterns we thought they 
did.  But the system using the 14-bay antenna would need only 41% of the 
applied r-f power needed by the 6-bay system.

RF