Dual-band microstrip filtering antennas with symmetrical slots

Abstract

Two dual-band microstrip antennas with filtering responses are proposed in this letter. By introducing symmetrical slots (One is a U-shaped slot, and the other is an inverted H-shaped slot) at the edge of rectangle patches, additional resonant modes are induced, and both of the antennas have dual operation bands. More importantly, extra radiation nulls are observed between the two bands. In addition, the proposed antennas are fed by microstrip lines with two pairs of symmetrical open stubs, which offer two more radiation nulls at low frequencies. Thus, dual-band filtering responses for the proposed antennas are obtained. Simulated and measured results show good agreements with unidirectional radiation patterns, as well as high selectivity of realized gains.