A Linearly Polarized Low-Profile Complementary Antenna with Enhanced Bandwidth and Wide Broadside Beamwidth

A linearly polarized low-profile complementary antenna with enhanced bandwidth and wide broadside beamwidth is proposed. To realize a wide half-power beamwidth (HPBW), an equivalent electric dipole is introduced by the strip on the bottom layer at first. As seen, it not only contributes to the beamwidth enlargement in yz -plane due to the superposition of complementary sources but also introduces a lower resonance. Then, in order to obtain a broad bandwidth, a stub is crossed on the strip to make the lower resonance move up, meanwhile merging with the higher one. After this, a tapered aperture structure is employed to reduce the input inductance for a further bandwidth enhancement. Finally, antenna prototype of center frequency 5 GHz is fabricated and tested. As experimentally demonstrated, a wide HPBW up to 180° and a broad bandwidth around 30% are achieved under a low-profile about 0.035λ0 as well as excellent gain flatness property, which outperforms most of the reported counterparts.