Wideband Differentially Fed Patch Antennas Under Dual High-Order Modes for Stable High Gain

Wideband differentially fed patch antennas under dual high-order modes for stable high gain are proposed in this communication. The working principle is verified on a differentially fed circular patch antenna operating in TM 31 and TM 12 modes at first. Two open slots are loaded to the patch's edge to reconstruct the current distribution of TM 31 mode, thus substantially increasing the broadside radiation. An additional slot is introduced at the patch center to perturb the TM 12 mode and reshape its current to be more in-phase, by which sidelobe radiation is dramatically reduced. With use of loading of slots and shorting pins, the two modes are allocated in resonant frequencies to make up an enhanced bandwidth of 13.4% and produce high gain up to 13.7 dBi, with the beamwidth and gain level nearly unchanged in band. Then, the proposed method is further developed on a rectangular patch antenna, where three cascaded slots and four shorting pins are loaded to perturb TM 21 and TM 03 modes, and reshape their current distributions. In a similar way, the broadside radiation of TM 21 mode is enhanced and the sidelobe of TM 03 mode is suppressed. At last, the antenna obtains a bandwidth of 12.4% and stable realized gain as high as 14.0 dBi.