Wideband via-Loaded Cylindrical Open-Ended SIW Cavity Antenna

A composite cavity-based antenna is proposed and presented in this work. Three kinds of modes of the composite structure are involved to obtain a wide bandwidth: the TE111/2 cavity mode of a cylindrical open-ended substrate integrated waveguide cavity, the odd TEM mode generated by loading two rectangular via holes inside the cavity, and the higher-order loop modes (L-3 and L-5) of a circular ring detached from the cavity by a circumferential slot located at the cavity's side wall. In the implementation of the antenna, slot coupling feeding methodology is applied, which also introduces a resonance for the bandwidth enhancement. A simulated fractional impedance bandwidth of 57.3% with vertical bar S-11 vertical bar < -10 dB from 24.9 GHz to 44.9 GHz is achieved (vertical bar S-11&VERBAR = -9.7 dB at f = 27.7 GHz is ignored). The antenna has a broadside radiation pattern within the operating frequency band and a maximum simulated broadside gain of 10.6 dBi at f = 27 GHz. Multi-layer technique and metallized via holes processing, which become commercial nowadays, are two critical techniques of the presented antenna. The simple structure is benefit of the fabrication and the integration with other planar front-end circuits. The antenna is fabricated and experimentally verified. A small difference is observed between the measurement and the simulation. A measured fractional bandwidth of 52% from 27 GHz to 46 GHz (vertical bar S-11&VERBAR = -9 dB at f = 29 GHz is ignored) and a measured maximum broadside gain of 9.5 dBi are achieved.