Sub-THz On-Chip CPW Monopole on InP with Cross-shaped Slot for Bandwidth Enhancement

THz communications call for highly integrated wireless chips. This paper presents the first, on-chip sub-THz coplanar waveguide (CPW)-fed monopole antenna covering the full J-band (220-330 GHz), on an Indium Phosphide (InP) substrate. The antenna is designed on a high-permittivity Indium Phosphide (InP) dielectric substrate with a single layer of metallization. Targeting multi-GBPS communication applications, the antenna is designed to have an S
11
bandwidth covering 230–330 GHz. Through the addition of a cross-shaped slot to the monopole's radiator, the fractional bandwidth is improved by nearly three-fold, from 11.1% to 29.6%. The designed antenna features stable radiation patterns throughout the entire operational frequency range, with a single element gain over 3.8 dBi, while maintaining a small footprint of 330 µm x 225 µm (0.25λ × 0.17λ
0
at 230 GHz).