A Low-Profile Wideband Patch Antenna With Consistent Radiation Patterns Based on Dual Antiphase Modes

A low-profile wideband microstrip patch antenna (MPA) with consistent radiation patterns is proposed based on dual antiphase modes. First, a pair of narrow slots and a differential-fed scheme are introduced to excite antiphase modes with dual resonances. The mechanism is analyzed by the electric fields and magnetic current distributions. The antiphase TM<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">20</sub> mode has broadside patterns due to in-phase magnetic currents. Second, a pair of wide slots is etched to eliminate the radiation null produced by the antiphase TM<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">22</sub> mode and to suppress the unwanted TM<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> mode. Thirdly, four shorting pins are loaded to improve impedance matching and to achieve a dual-mode combination, which further enhances the bandwidth. Besides, the bandwidth variation of antenna evolution is investigated. Measured results show that the bandwidth can be significantly enhanced to 45.7% [(5.9 to 9.4) GHz] with a low profile of 0.02λ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub>. The proposed antenna achieves consistent broadside radiation patterns with a peak gain of 9.48 dBi.