I'm sorry, I didn't say what I intended to. What I meant for step 2 was:

2. Assume for a moment that all the power was in a single front lobe.
Calculate how much, in dB, that front lobe power would be reduced by
putting the fraction in the rear lobe which you calculated in step 1.

It's been a long, long time since I took an amateur exam. But I'd think
the ability to make these calculations would be within the reach of
anyone who passed the General class exam.

Roy Lewallen, W7EL

Roy Lewallen wrote:
*Sigh*. Guess I'll try one more time.

Suppose that the Yagi has a front/back ratio of only 6 dB, and that the
angular span ("height" and "width") of the rear lobe is the same as that
of the front lobe.

1. Figure out how much power is contained in the rear lobe compared to
the front lobe.

2. Express that ratio in dB.

That's the amount you'd gain by eliminating all the power in the rear
lobe, and moving it into the front lobe -- if you can do it without
increasing the angular span of the front lobe.

Repeat with a 10 dB front/back ratio or whatever you think your present
Yagi has.

Now, that wasn't so hard, was it?

Roy Lewallen, W7EL