Broadband Filtering Dielectric Resonator Antenna With Wide Stopband

A low profile stacked dielectric resonator antenna (DRA) and a microstrip metasurface (MS) antenna are investigated and compared in this communication. It has been found that very similar radiation performance including resonant modes, reflection coefficients, boresight gains, and radiation patterns can be obtained between them, indicating that the dielectric superstrate of stacked DRA plays analogous role with MS in enhancing the antenna bandwidth and realized gain. Based on this observation, a broadband, low profile, and high gain filtering cylindrical stacked DRA is inspired by an MS-based filtering antenna. Four resonant modes including the higher order HEM
_31δ
mode and HEM
_13δ
mode are simultaneously excited in the DRA to provide a broad bandwidth of 61.4% and a peak gain of 11.4 dBi within passband, whereas a shorting via and two pairs of transverse stubs are introduced into the feeding microstrip line to generate radiation nulls in stopband and realize filtering function. Second harmonic suppression has been achieved without increasing the footprint of the antenna, and an out-of-band suppression of more than 23 dB is obtained within the wide stopband.