Design and Characterization of Wideband Dual-Polarized Double-Slot Lens Antenna with Low Cross-Polarization at sub-THz in SiGe-BiCMOS

Abstract

This work details the design and characterization of a wideband on-chip dual-polarized double-slot antenna for sub-THz frequencies, integrated in SiGe-BiCMOS technology. The proposed design features two perpendicularly arranged double-slots that provide dual-linear polarization and efficient illumination of dielectric lenses through the silicon substrate. To decrease the level of cross-polarization, a number of parasitic slots are added. Two feeding architectures have been studied, leading to two different prototypes. The first is designed in a 130 nm SiGe-BiCMOS process and is tailored for integration with single-ended circuit topologies. It achieves a maximum antenna efficiency of 63% in its operational bandwidth of 170-250 GHz, with a cross-polarized component lower than −22 dB up to 240 GHz. The second prototype is designed in a 90 nm process and is suited for differential circuits. A 55% fractional bandwidth is achieved around the central frequency of 287.5 GHz, with a maximum antenna efficiency of 56% and a cross-polarized component lower than −19.5 dB. The port isolation is better than −37 dB up to 300 GHz. Both prototypes are characterized in the 200-325 GHz frequency range, with very good agreement between the measurements and simulations.