Wideband Designs of Offset U-slot and Dual U-slot cut Rectangular Microstrip Antennas

Wideband designs using U-slot consists slot cut in the patch center with the symmetric position of the feed point with respect to U-slot. The U-slot position governs which higher order resonant modes contribute to the bandwidth enhancement. In the literature, U-slot cut configurations using its offset position have not been explored for the bandwidth increment. This paper presents various wideband designs of rectangular microstrip antennas using the combination of the offset positions of the U-slots and the rectangular slots. The detailed resonant mode based study is presented. A bandwidth greater than 300 MHz (>30%) is obtained using two offset U-slots and rectangular slots. This optimum configuration results in peak gain of above 8 dBi and exhibit stable gain characteristics across the impedance bandwidth. Further, a detailed study to explain wideband response in double U-slot cut antenna is also presented. The proposed multiple offset slots cut designs can find application in the mobile communication systems.