Dual-circular polarised patch antenna array on LCP for 60 GHz millimetre-wave identification

This paper presents a design of a dual-beam circular polarised patch antenna array operating at the 60 GHz frequency band. The circular polarisation is achieved by using circular-polarised patch antenna elements and sequential rotation technique to construct a four-element array. Two separate feed networks are implemented to excite the left- and right-handed circular polarisations. One of the feed networks produces a normal beam whereas the other excites a beam with a notch in the broadside direction. The two beams can be used for direction finding of tags in millimetre-wave identification applications. The antenna array is designed and manufactured on a multilayered liquid crystal polymer substrate and the design is validated through S-parameter and radiation pattern measurements.