How to improve return loss of microstrip fed slotted patch antenna?

I have made a microstrip fed slotted patch antenna. The patch antenna is fed by coupling between the microstrip line and 2 patches. I have got the dip at the right freq but it is of only -2.2db.

Any ideas on how to improve this figure?

pls send your hfss file here

Faced with this kind of question I would build a parametric model where I could change the various features (one at a time only) to see what the particular antenna sensitivity. Once I found what to manipulate tuning can proceed. Various software tools exist but the same thing can be done with copper tape and a razor blade. I would prefer to use HFSS for this problem. Opinions vary. Some of the 2D solvers might actually be better for this problem (cheaper and faster).


Physical experimentation is easier at lower frequencies (l and s bands). You could also consider scale models as a way te ease the process.

This is my antenna design. The original IEEE paper that i am implementing said that the microstrip line was 3mm wide but I have modified it to be 7.5mm because 3mm was having a dip of -2.2db and 7.5mm has a dip of -4.2 db.

I will be greatful for help. And yes, I used parametrics to select the suitable microstrip line value.

I am just wondering that if the IEEE paper had the results, y cant I get the same by making the exact design.

What is the name of the IEEE paper?