Dual band patch antenna with slot

[Hana Rashid]

Hello all.

I have a question. Is there any tutorial on designing dual band rectangular antenna.
I am working on dual band antenna, using CST, rectangular patch on FR-4, to resonate at 2.4GHz and 5.2GHz. I have tried inserting slot on my single patch (2.4GHz) but the gain keep reducing (from -24dB to -16dB).
Any tips on designing?
I know some basic rules: Length of slot = lambda/2. But what about the position of slot? And width? and material on cst-is it nickel for slot?

Please help! I am at my wits end.
Thanks in advance.

 

[vfone]

but the gain keep reducing (from -24dB to -16dB).

If the antenna gain is in dBs, -16 is greater number than -24, which makes the antenna gain increasing and not reducing.

 

[Hana Rashid]

If the antenna gain is in dBs, -16 is greater number than -24, which makes the antenna gain increasing and not reducing.

vfone, sorry my mistake. its the return loss S-11

 

[vfone]

All right, but better or worse S11 not always make the gain of the antenna higher or lower.
If your S11 is better than -10dB (VSWR 2:1) on both bands the antenna should be fine from this point of view, and you can spend time for improving the Antenna Radiation Efficiency, which actually is the real gain parameter of the antenna.

 

[Hana Rashid]

Yes but the problem is my 2nd resonant seen to be at 3.3 GHz. I want it to resonate at 5.2GHz and it seems far from it. Anyone have done simulation on dual band slotted patch antenna? Pls advice me on how to get the frequency resonant at 5.2GHz; what would be the best slot dimension (LxW), slot position and shape (H, U, E or any). Pls. Need help on this.
Thanks