A substrate integrated waveguide (SIW) based self-quadruplexing antenna and its design approach in Ku-band (12–18 GHz) is presented in this paper. This consists of splitting of TE220 mode of square-shaped SIW cavity by incorporating the two diagonal arrays of metallic vias. Accordingly, four orthogonal dominant mode triangular shape SIW cavity (DMTC) resonators are formed. This methodology ensures enhanced isolation. To achieve the broadside radiation, the cavity structure is fed using microstrip lines and rectangular slots are loaded on the top layer of each DMTC. The length and position of each rectangular slot being chosen such that quad-resonances are achieved at 13, 13.5, 14.3, and 15 GHz for the respective DMTC. The equivalent circuit model of the proposed design is also developed, and the tuning of each frequency band is analyzed without affecting the others. The proposed antenna is producing high isolation (>28 dB) among all four ports and a unidirectional radiation pattern with a high front-to-back ratio (>26.8 dB).

This paper presents a cavity-backed dual-slot antenna in 0.13-μm SiGe BiCMOS technology. The dual-slot structure is excited by a cross-shaped strip line and a cavity which is formed by the topmost metal layer connected to the bottom metal layer through vias in between. By adopting dual-slot and cross-shaped feed line, the bandwidth is significantly enhanced by 196% compared with the single-slot antenna with straight feed line. The reason for bandwidth enhancement has been analyzed. The proposed antenna shows a measured impedance bandwidth of 15.2 GHz from 248.2 to 263.4 GHz for |S11| < −10 dB. The simulated and measured peak gains of the cavity-backed dual-slot antenna are −1.3 and −2.1 dBi, respectively. The simulated radiation efficiency is 31.1%. The total size of the antenna is 0.46 mm × 0.48 mm.