Millimeter-Wave Low Side- and Back-Lobe SIW Filtenna Array Fed by Novel Filtering Power Divider Using Hybrid TE₁₀₁/TE₃₀₁ Mode SIW Cavities

Abstract

In this article, a novel and simple design approach of millimeter-wave (mm-wave) low side- and back-lobe substrate integrated waveguide (SIW) filtenna array is investigated by using predefined filtering power divider (FPD). The FPD consists of two coupled SIW cavities operating at TE101 and TE301 modes, respectively. The TE301 mode divides the energy from Cavity 1 into three parts equally and three outputs are loaded to Cavity 2 for power distribution, making the FPD design simplified. Based on this, the predefined power splitting ratio (1:1:1 and 1:3:1) of the FPDs can be obtained easily by controlling the output external quality factor (Qe). Accordingly, the side and back lobes of the filtenna array are suppressed by using the proposed FPD with predefined power splitting ratio of 1:3:1. To verify the proposed approach, a 3 × 3 filtenna array prototype centered at 27.2 GHz is designed, fabricated and measured. The measured results show an impedance bandwidth (|S11| < -10 dB) of 1.8 %. The filtenna array performs good gain-passband selectivity with an in-band peak gain of 11.1 dBi, and the side lobe is suppressed more than 20 dB while the front-to-back ratio is over 30 dB. Good agreement is achieved between simulated and measured results.