How to increase bandwidth in dual-band antenna??

[raymondli]

Hi all,


I design dual-band microstrip antenna using the formula of Freq=light speed / 4( length+width) for both lower and higher operating freq. There is a U-shaped slot on the radiating element........

However, it seems that the higher freq one always has a narrower bandwidth.......narrower than the lower freq one. So I want to find out what method can do improvement on its bandwidth for the higher operating freq?????

 

[jbartos]

Suggestion: Visit

http://www.eng-tips.com/viewthread.cfm?spid=247&newpid=247&sqid=48092&tmac=logc

http://www.ece.queensu.ca/hpages/faculty/freundorfer/V5/wireless/antennae/aper_coup_ant_1.html

http://www.cwc.nus.edu.sg/~chenzn/MOTL-0802.pdf

etc. for more info. The physical design needs to be finetuned. There may be cross-polarization, etc.

 

[buding]

What kind of feed system do You use? Maybe it is possible to improve bandwidth by making better feed circuit.