How can I increase my antenna impedance bandwidth?

[liling_03]

Dear all,

Please help me!
Currently I am doing antenna design, Rectangular patch antenna with a novel coplanar waveguide fed diamond patch for UWB application, the ground layer and diamond patch are the same later on PCB, another layer of PCB have no copper plane.
The frequensy range required is 2.27GHz to 10.63GHz.
With my pre-design based on some reference design searched on web. I only able to obtain freq range of 4.5G to 10GHz (simulation result).
Below are some of my modification done, wrt the pre-design:
1) Increase distance of patch and ground plane->freq range: 3.5G-9.5GHz
2) Increase the board substrate(RT/duroid 5870 Er=2.33) thickness->freq range: 4.1G-9.9GHz.

Appreciate if you have any other idea on achieving the frequensy range hence to obtain higher impedence BW?

Regards/Lingling.

 

[zorro]

Hi Lingling,

That frequency range is a lot for a patch antenna. With which VSWR do you define bandwidth?
BW can be increased creating multiple resonances.
Techniques for achieving that include coplanar parasitic elements or stacked patches (one more layer required) among others.
regards

Z

 

[liling_03]

Dear Mr.Z,

Thank you for the post
Yes. The patch antenna is for the UWB application. I using VSWR=1.95 (S11= -10dB).
The impedance BW to be achieved is (7.5G-8.36GHz), however, I do have 6GHz at this moment.
May I know if multiple resonances is a good or bad phonomena for antenna circuit?
Appreciated for the recommendation. I am reading it now

Best regards/Lingling.

 

[zorro]

Hi Lingling,

Multiple close resonances is a good phenomenon used as a way to broaden the bandwidth of the antenna.
The topic is discussed in the bibliography. If yuo can, take a look at this book:

Microstrip Antenna Design Handbook (Garg, Bhartia, Bahl, and Ittipiboon - Artech House, 2001), Chapter 9, "Broadbanding of Microstrip Antennas".

Regards

Z