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Semianalytical design approach to a triple‐mode resonant, wideband null frequency scanning sectorial monopole antenna is proposed. As is demonstrated, TE3/5,1, TE9/5,1, and TE3,1 mode within a 150°, circumferentially resonant sectorial monopole are simultaneously excited to realize null frequency scanning functionality. The prototype antenna exhibits a wide impedance bandwidth of 75.3%, ranging from 1.40 to 3.09 GHz. Within the frequency band of 1.55–2.70 GHz, the radiation null linearly scans from θ = +90° to +8° with a null frequency scanning sensitivity of 12.9 MHz/°. Moreover, the antenna possesses maximum gain of 2.5 dBi in the backfire, ‐x‐direction, which indicates that it should exhibit quasi‐unidirectional radiation pattern in the azimuth plane. [ABSTRACT FROM AUTHOR]

Design approach to a planar unidirectional, complementary dipole antenna under quadruple mode resonance is proposed. The design initiates from a planar complementary dipole antenna, with a pair of flat electric dipoles to be closely incorporated with a slot element. As theoretically predicted by the equivalent multi‐source model, quadruple mode can be successfully excited to yield unidirectional antenna with a height of about 0.04‐wavelength. As have been numerically demonstrated and experimentally validated at the 2.5‐GHz band, the antenna can be implemented on air substrate of 5 mm (i.e., 0.041‐wavelength). The prototype antenna can exhibit a wide impedance bandwidth up to 31.5%, in which an available quadruple‐mode bandwidth of 5.2% is attained: The antenna can exhibit a maximum front‐to‐back ratio up to 13.0 dB, with nearly equal radiation patterns in both E‐ and H‐planes. As is concluded, the quadruple resonant mode has been successfully incorporated to a slot element and then to yield fully‐integrable, unidirectional, planar complementary dipole antennas for the first time. [ABSTRACT FROM AUTHOR]