Circularly Polarized Sub-THz Antenna Design for Distributed Deployment

Sub- THz deployment is challenging due to high propagation losses, necessitating dense deployment. To reduce cost, RF signal can be distributed via plastic fiber to remote radio units to increase coverage area. In this paper, we propose an antenna-in-package concept for the single-layer substrate on low-cost embedded wafer level ball grid array (eWLB) packages. To suppress the distortion in the broadside pattern from the coplanar waveguide feed line, the circularly polarized patch antenna is surrounded by an integrated loop structure. The loop also enhances the antenna bandwidth by adding a second resonance. Simulation results show that the proposed antenna offers broadside coverage with the 10 dB impedance and 3 dB axial ratio bandwidths of 14.2% and 11.2% at 145 GHz, as well as realized gain of 7.8 dBi. The antenna shows good promise for array implementation on eWLB packages.