[TowerTalk] K7GCO's first-order estimate

[Chris Burger]

K7GCO wrote:

> Only with all 5 of these [director parameters] "totally optimized" will
you 
> get a maximum of about 1 dB... [added to the gain of a Yagi for a single
added 
> director]

and

> So you tell me how a guy wire that is not of a resonant or a certain
length, 
> not in the same plane out front and not of the same polarization going to
upset 
> the beams pattern or SWR?

The answer is simple, at least for beam pattern.  As has been mentioned, the
effect of stray guy radiation is mainly to the nulls in the pattern.
Assuming a null of -20 dB relative to the maximum lobe, you need only 1% of
the power reradiated by a guy to upset the pattern.

On the other hand, to add 1 dB to the gain, you need the reflector to add
around 26% to total radiated power in the favoured direction.




Chris R. Burger
ZS6EZ

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