antenna-theory.com

[JulianCavinaugh]

Dear,

I am designing the microstrip patch antenna. The criteria is reflection coeffient is below -20dB at the resonant frequency at 15 GHz, the range of frequency to optimize runs from 12 to 18 GHz, the reflection coefficient in this range needs to be less than -10dB for the wide area scanning. However, the best results I could achieve is -35dB at 15GHz, and from 12 to 14 GHz, the ref. coef is approximately 0dB, which is really bad results. This results is from the optimization of the dimension of the patch. My patch is fed by 200 ohm microtrip feed. Do you have any idea for enhance to dimension of the patch to get the better results for refl. coef. Please help.

Thank you very much

[admin]

That design sounds extremely difficult, if not impossible.

The bandwidth of patch antennas is not large, so it will be tough to get the required bandwidth. Try the following:

1) Increase the height of the substrate (the dielectric between the ground plane and the patch). Higher heights give wider bandwidth
2) Use air for the dielectric
3) Increase the width of the patch (which will increase the bandwidth and also decrease the input impedance, so you will need to optimize the feed position)
4) You may need to place parasitic resonators around the patch, or cut u-shaped slots. This increases bandwidth as well.