Dipole filtering antenna with quasi-elliptic peak gain response using parasitic elements

A dipole filtering antenna with a quasi-elliptic peak gain frequency response is proposed. It consists of a driven dipole, a parasitic resonator and a parasitic meandered resonator with the same resonant length. By introducing these two parasitic elements, the proposed antenna has two reflection zeros in the passband and two radiation nulls in the stopbands. An antenna prototype centering at 1.85 GHz is fabricated. Measured peak gain and radiation efficiency achieve minimum values of -7.95 dBi and 4.23% at 1.73 GHz and -4.17 dBi and 7.78% at 1.92 GHz, respectively. The roll-off factor of peak gain is 182.52 dB/GHz at the lower sideband and 281.27 dB/GHz at the upper sideband, respectively. Measured results verify the effectiveness of the proposed design. Compared to conventional dipole antennas, the proposed antenna achieves widen impedance bandwidth as well as filtering frequency performance such as flat passband gain, steep sideband selectivity and high stopband suppression.