single patch antenna design

Hi,

I am designing a single rectangular patch antenna for 2.4Ghz. i am using inset feed. I used the std formulas available in Balanis to cal the length and width of rectangular patch.

The length = 30mm, width=38mm, Er=4.4,height of substrate(fr4)=1.6mm. The feed width was 0.5mm.
I am using ADS software for stimulation. The results were

@2.322GHz |S11|=-11db. which means the return loss is 11db. This was my max return loss. @2.4Ghz the return loss was around 5db.
I would like to improve my results....
I want a return loss greater than 17db at least.And the frequency should be very closer to 2.4Ghz.I have planned for fabrication .so i cant change the Er.
so pls tell me a way to improve my result.

Thanks
shobi

Heya Shobi (and apologies for not having any EM simulators to hand at this moment for some better guidance) but ... perhaps check/optimise your feed network?

I recall designing a similar patch (same frequency, FR4, same thickness) some time ago using a coaxial probe feed. From memory, the patch size was ~28 x 38 mm. The 28 mm dimension was a sensitive function of the substrate permittivity and the desired resonance frequency. With the middle of the patch grounded, I found feeding the patch at a point offset ~7.5 mm from the centre (along the short dimension) gave a pretty good match into 50 ohms (S11 < -25 dB). The bandwidth (over which S11 < -15 dB) was approximately 70 MHz. With FR4, don't put too much faith in the simulated results, as I found when the design was put into production, the centre frequency wandered around +/- a few 10's of MHz (primarily as a result of substrate Er variations). Similarly, the match varied between batches, but was always well < -20 dB.

Good luck!

(Try letting ADS's optimiser loose on the patch length and feed network and see what it comes up with

Hello everybody,

I am trying to design 2.45GHz patch on ADS using FR4 substarte.But i am unable to find the substarate paramters i.e thinkness,height and dielctric constant.

I dnt know how should i proceed.

---------- Post added at 16:09 ---------- Previous post was at 16:03 ----------

Hello everybody,

I am trying to design 2.45GHz patch on ADS using FR4 substarte.But i am unable to find the substarate paramters i.e thinkness,height and dielctric constant.

I dnt know how should i proceed.

SIM001
I am also newbie here but I think you can check dielectric constant of FR4 from your software. Before designing a patch antenna you should first set e, f, and h height of substrate, then calculate the w,l width and length of your patch.