I'm now designing a UHF tag antenna with inductively coupling. For UHF band, the operating range of frequency is from 908MHz ~ 914MHz. However, from my simulation result of return loss - frequency, I found out that the minium point of return loss was left shifted (around 820MHz). How can I improve my design so that the whole curve of return loss can be re-located inside the UHF band?
Thanks for your suggestion. I had made an improvement after adjusting the dimension of patch. However, the diagram of return loss had an undesirable peak at the RHS of the frequency. What should I do to eliminate this peak?
I wonder how you get a positive dB return loss. Is your antenna generating energy?
I'm not familiar to HFSS, but something seems to be wrong in your simulation setup.