I am attaching a paper which explains that if we insert additional patches inside the mail patch, it's parastic reactance helps in better S11 and Gain.
Same way I started from a basic structure @25 G Hz. I was having a radiation efficiency around 68 %. However when I added 2 patches inside the main patch, although the S11 improved, but the radiation efficiency badly effected to 33%.
Where am I wrong, please guide. I am attaching the discussed above
Regards
Radiation efficiency is reduced because of the impedance mismatching. When parasitic patches are inserted, the impedance matched feed point is disturbed which effects the results. The inset feed width may enhance the S11, gain, and radiation efficiency. Try to modify the feed line width and check if it helps.
I think you probably don't have enough of the original patch left to be resonant, so you may only have radiation from the two new patches. The small strips left around the outside of those patches are very narrow, and I am not sure what the centre part will do. Radiation is from the edges nearest to and furthest from the feed line and I would expect that radiation from the edge nearest the feed will be nearly nothing with the new patches inserted. I think you may need more of the original patch remaining.
Thanks both of you. I tried both of the suggestions. The feed width variation has shown significant effect on S11 parameters but still I could notice only a marginal effect on the radiation efficiency. As suggested by White, I could notice marginal improvements when changes are made in radiation edges. I was expecting a good variation in S11 parameters w r t radiation edges and efficiency improvements w r t non radiating edges variation, which could not happen. Let me try some more iterations with some changes in substrate thickness.
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