antenna-theory.com

[opticalc]

On the Impedance page
http://www.antenna-theory.com/basics/impedance.php

there is an equation just under Figure1 that I dont understand how the equation was derived. I know all the ohms law equations regarding volts/ohms/amps/power but this one just seemed odd.

I understand what the equation is trying to convey, I just dont get where it came from.

The tutorial says "From circuit theory, we know that P=I*V." and that is very familiar, but then they have power = (V*V*Za) / (Za+Zs)^2 and I just dont have any idea where that one came from.

[admin]

Power Delivered to antenna = (Voltage Across Antenna)*(Current Through Antenna)

What is the current through the antenna?
What is the voltage across the antenna?

And that is where the equation comes from