Dave Shrader wrote:
I don't have an IEEE dictionary so I stand corrected. However, 100 watts
into a Yagi, Quad, Log Periodic, or 4-square and 100 watts radiated is
still 0 dB gain.

Gain = 10 * Log[Pout/Pin] = 10 * log [100/100] = 10 * 0 = 0 dB.

It also has 0 dB attenuation!!!

NB: Valid over either 4*Pi or 2*Pi steradians.

What you've calculated here is efficiency, not gain. It's important to
understand the difference between the two if you want to communicate
with others about antennas.

Roy Lewallen, W7EL