Total radiation efficiency = antenna efficiency

I have some dilemma on the antenna design parameters which I need some of the forumers expertise.

I design antennas that showed me

-reasonably good S11 but lower total radiation efficiency ~30%
-bad and out of band resonant S11 but much better total radiation efficiency ~40-50%

I suspect energy had been drain for the antenna with 30% efficiency. but is it normal for the second case which has a S11 of -3.9dB?

During design stage, should we always focus on making sure we get high radiation efficiency before checking and tweak the S11?
is equation below make sense?

Total radiation efficiency = (antenna efficiency) x (mismatch loss)

where can I study more on this?

million thanks :)
Spid3rx

The last equation make sense and is not something special to explain. Total radiation efficiency includes also the power lost due to poor VSWR (or mismatch loss).
Usually steps for antenna tuning are, first tune for best antenna efficiency and second for good VSWR. But this is not mandatory, can start tuning whatever you want, just make the overall antenna performances good.

@vfone,

thanks for the information. since total radiation efficiency is a multiplication of antenna efficiency and mismatch loss, with higher
antenna efficiency, usually it can try to offset the minimal loss of S11 at -4dB ?

how do we calculate based on the equation in terms of %? lets say ant efficiency ~ 80%, mismatch loss ~ 10% , hence total radiation efficiency ~ 80% ?

thanks

I think you have to multiply the radiation efficiency and the (100% - mismatch loss).
This will give you a total efficiency of 72%

For example if 1W of total power gets to the antenna
0.1 W is lost because of the mismatch (10% mismatch loss)
From the remaining 0.9W are 80% radiated = 0.72W
So the total radiation efficiency is 72%

hi, can you help me for write the equation for efficiency in J class in harmonic balance?
is it true?
100*pload_w/(vcc[0]*i_dc.i[::,0])
in my circute gives me 0.002% but in the paper gives 60% why?
do you give me your email to send my file and solve my problem? pleaseeeee
thank you