Analyses of the effects of slots loading on the microstrip patch for dual-frequency operation

The electromagnetic characteristics of a slotted rectangular microstrip antenna is studied. The microstrip antenna is fed by a single probe feed and has a slot with a pair of step-slotted arms embedded close to the patch's radiating edge. By varying the length, the spacing of the two arms, the narrower-section width, and the wider-section width of the slot, a tunable frequency ratio ranging from about 1.127 to 1.616 can be obtained. Details of the antenna performance and simulated results are presented and discussed.