340-GHz SIW Cavity-Backed Magnetic Rectangular Slot Loop Antennas and Arrays in Silicon Technology

A 340-GHz on-chip antenna (OCA) with highgain and high-radiation efficiency is designed using a standard 0.13-mu m SiGe BiCMOS technology without any postprocesses. In the proposed OCA structure, a rectangular slot loop is etched in the upper wall of a substrate integrated waveguide (SIW) to form a magnetic current loop radiator. The SIW structure forms a back cavity to suppress the surface waves and separate the radiation aperture from the low-resistivity substrate. Furthermore, the side wall of the SIW cavity and the edge of the slot form a lambda(g)/4 resonator to reflect the power back to the slot loop. As a result, the radiation efficiency is improved. By etching a slot properly in the SIW upper wall, another resonating point is constructed and hence, the bandwidth is broadened. Single antenna element and a 2 x 2 array are both designed and fabricated with-and without-the slot structure; a maximum gain of 7.9 dBi with the radiation efficiency of 48% at 340 GHz is achieved for the proposed SIW cavity-backed antenna structure.