Microstrip square-ring antenna with capacitive feeding for multi-frequency operation

In this paper, a new compact microstrip square ring antenna is presented, which can be operated at multiple frequencies. It can be stated that within a stacked microstrip square ring configuration, a third square ring is accommodated, which operates at a higher frequency than that of the stacked configuration. Thus, three resonators are arranged in a compact form and fed capacitively to successfully operate at three frequencies.