Ron wrote:

On Sun, 09 May 2004 17:26:05 GMT, Dave Shrader
wrote:

SNIP

So you can use the formula I^2*R (which is for finding P) without
knowing the variable "I" to find the resistance (Ra)?

I don't think so. Unless you have a magic wand, Harry Potter :-)

Ron

You certainly can!!

Total power to the antenna SYSTEM = I^2*(Rr + Ra + Rg).

Total power radiated = I^2*(Rr).

When you divide the two terms to get efficiency the I^2 term cancels.
This leaves Rr/(Rr + Ra + Rg). The current terms drops right out!!

DD