A Low-Profile Broadband Filtering Dielectric Resonator Antenna Based on SISL With the Improvement of Suppression Level

To achieve a low-profile, wide-bandwidth, and highly selective design, this paper presents a substrate integrated suspended line (SISL) based broadband filtering dielectric resonator antenna (DRA) with the improvement of suppression level. The dielectric resonator is cylindrical and fed from the bottom by a microstrip-coupled slot. The dual head structure with the designed open stub can provide two radiation nulls on both sides of the passband for the filtering function and can excite three resonant modes (HEM
$_{11\delta} $
, HEM
$_{11\delta} $
, and TE131 mode) at different resonant frequencies to enlarge the impedance bandwidth of the proposed antenna. Then, adding a metal branch perpendicular to the feeder can offer a radiation null to eliminate the undesired resonances in the right stopband. Finally, the suppression level at high frequency is improved further by filling Sub2’s cavity with FR4. A prototype has been manufactured and measured for demonstration. Measurement shows that the proposed antenna has a - 10-dB impedance bandwidth of 32.9% (2.98-4.15 GHz), a flat gain within the passband, and the gain suppression level within the stopband exceeds 15.5 dB.