Discussion Forum

Note: I use the RF module, which as I recall has most of the same variables as the wave optics module, so the notes below may work for you.

There are at least two ways to compute the radiation efficiency:

1. You can evaluate the input power at the feed and separately evaluate (integrate the normal component of the Poynting vector) over the external (absorbing or scattering) boundaries. The radiation efficiency = power radiated / power input.

2. Alternatively, you can compute the resistive power lost (aka, heating) in/on the antenna, again via an appropriate integral (surface or volume). In that case, the radiation efficiency = 1 - (resistive loss / power input).

Note that if the efficiency is high (as it often is), the second method will likely yield more accurate results, since power radiated and net power input are often very close and the code always has some numerical errors associated with the discretization.

Finally, if you are instead thinking about the aperture efficiency, that would be quite different. See https://en.wikipedia.org/wiki/Antenna_efficiency .

Thankyou sir, How to evaluate input power at the feed gap.

Well, I don't know what kind of feed you have. If it is an aperture feed, integrate the normal component of the Poynting vector over it. If it is a lumped circuit-type feed, you can multiply V by I there. Perhaps you should post your geometry and file so that the question is clearer.