realized gain vs gain hfss

Recently, I'm simulating an antenna using HFSS. And I found Gain and Realized gain. I read the manual but do not understand. I think Realized gain is the gain we usually refer to. But what does the Gain in HFSS stand for? Please give me some instructions. Thank you.

Hi,

First u need to understand the following

incident power (Pinc) = 1W
accepted power (Pacc) = Pinc * (1 - s11^2 ) (ie mismatched loss)
radiated power (Prad) = Pacc * radiated efficiency

and the gains are calculated as followed:

realised gain = 4piU / Pinc
gain = 4piU / Pacc
Directivity = 4piU / Prad

If you think carefully, realised gain is smaller than gain. But of course realised gain has included all the facts that an antenna has some mismatching loss and loss in efficiency. While gain and directivity excludes one of these losses respectively.

But which is the gain we mostly refer to, GAIN or REALIZED GAIN?

Given that you are measuring your 'gain' through your 50ohm coaxial cables, you will experience some mismatched loss and loss in radiation efficiency in your antenna system. So I think realised gain is what you expected to be measured.

I see. Thank you!