Matching/Transformation Network for Freq depndt Impedance?

Hi,

I feed to feed a Patch Antenna (Edge Fed with MStrip Line) where the Input impedance at the edge of my antenna varies from rapidly over my band of interest. Note: I have resonance at the centre freq but below and above that its comples Impedance.

Any suggestion on what kind of matching/transformation circuit (MStrip) can be used to address such problem. I am not talking about perfect matching. Anything better than fixed matc at centre freq is wellcome.

Thanks.

The bandwidth of this edge-feed patch antenna is very narrow.

Suggested matching method:
1. Single stub matching
2. cut slot matching

I designed a 2.4 and 4.9Ghz antenna using method 2. My experience is that the width and the length of the cutting slot is very sensitive to impedance. I suggest you start from width=0.5mm and length=2.0mm and increase the length every 0.5mm each time. You may see the bandwidth increase.

The slot of my final design are:
2.4GHz: length=8mm; width=0.5mm
4.9GHz: length=4.5mm; width=0.5mm

Below is a link for centre-feed patch antenna.

h**p://www1.i2r.a-star.edu.sg/~chenzn/IEEE-T-AP-0303.pdf

Good Luck!

NY