Efficiency and Gain Enhancements of 140-GHz On-Chip Microstrip Patch Antenna Without Enlarged Aperture

In this letter, a 140-GHz on-chip microstrip patch antenna in 130 nm SiGe BiCMOS is proposed. Limited by the low thickness between the patch and ground plane, the radiation gain and efficiency of the on-chip patch antenna are deteriorated. The defected ground structures (DGSs), which are utilized for bandwidth or isolation improvement in previous works, are introduced to increase the effective profile of the on-chip patch antenna, thus obtaining 1.3 dB gain and 15% efficiency improvements than the conventional on-chip patch antenna. Then, the location and dimension of DGSs are analyzed to develop a design guideline. For experimental validation, a prototype is fabricated and tested, and the measured results show agreement with the simulated one. Most importantly, the proposed antenna has a very simple structure without any off-chip loading components and possesses the same aperture as the conventional on-chip patch antenna.