Highly isolated broadband five-port circuit for V-band high data-rate wireless communications

Abstract

This paper presents an improved design of highly isolated broadband multi-port (five-port) circuit. The proposed structure is designed to operate over the unlicensed 60 GHz millimeter-wave frequency band, using very thin ceramic substrate (9.9 relative permittivity and thickness of 127 pm). This circuit is implemented using three rounded Wilkinson power dividers, and a 90° hybrid coupler to achieve a high isolation level between RF port inputs, and broadband operation. The S-parameter analysis of the proposed configuration demonstrates very good amplitude and phase balance, while maintaining a good return loss at all output ports, in the 57–64 GHz frequency band. These performances make the designed five-port circuit potentially suitable for unlicensed indoor V-band high data-rate communication systems according to the Federal Communications Commission (FCC).