antenna-theory.com

[sridhara]

Sir i have designed rectangular patch antenna in HFSS software and it resonating at 3different frequencies , i need to modify patch geometry to introduce slot on patch how to do that ,and how to make antenna to resonate @ UMTS band

[bigSteve]

Lets say you have an antenna that is resonating at frequency f1. If you want that antenna to resonate at a different frequency (say f2), then you can scale all dimensions of your antenna by the scale factor S = f1/f2.

That is, if your patch resonates at 900 MHz and has length L, width W, etc, you can get that to resonate at 1800 MHz by changing the length L to L*900/1800 = L/2, W can change to W*900/1800 = W/2, etc.....

Why do you want to add a slot to your patch antenna? I assume you are trying to increase the bandwidth or something like that? The way this is done in practice is to carve out a U-shaped slot or something, and adjust the slot width, length, shape iteratively until you get it to do what you want.

On a computer simulation, you would do the same thing. Make surfaces that represent the slot which overlap the patch surface, and then subtract the slot from the patch, and you have your patch antenna with the slits in it.

You can probably find some ideas on U-shaped slots and things in the IEEE Antennas journals, but don't try to recreate them exactly. Just start with the general idea and then tweak it to get it to do what you want. Play around with the parameters and figure out what works, then do it. Pretty simple actually.

Have fun