A Hybrid Radiator Filtering Antenna With -Shaped Patch and Annular Dense Dielectric Patch

In this letter, a hybrid radiator filtering antenna utilizing a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">θ</i>-shaped patch and annular dense dielectric patch (DDP) as radiators is proposed. Within the antenna's passband, the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TM</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> mode and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TM</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub>-<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">like</i> mode of the annular microstrip patch, and the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">HEM</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11δ</sub> mode of the annular DDP are excited. Two parallel branches loaded on the microstrip line introduce a low-frequency radiation null, while mutual coupling between the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">θ</i>-shaped patch and the DDP produces a high-frequency radiation null. The proposed hybrid radiator filtering antenna has been fabricated and measured for validation. Ultimately, the relative bandwidth reaches 11.65% (3.72-4.18 GHz), with an average realized gain of 8.27 dBi and a peak realized gain of 9.53 dBi. The realized gain ​​exhibits​​ relatively flat behavior within the passband. The proposed filtering antenna offers​​ advantages of low profile, high selectivity and flat realized gain.