Sequential-rotation arrays of circularly polarized CPW-fed aperture antennas in the MCM-D technology

This paper describes the design and characterization of a 2×2 sequential-rotation array (SRA) of novel circularly polarized antenna elements. The required feed phase-vector is achieved using a coplanar feeding network. The network is, for the first time, built using CPW lines in MCM-D technology. The array operates in the K-band around 25 GHz. The analysis is carried out both theoretically and experimentally. The results show that the sequential rotation increases the axial ratio bandwidth and enhances the isolation between the RHCP and LHCP polarizations. The proposed antenna element and sequential-rotation array enjoy high impedance bandwidth, high circular polarization bandwidth, and good isolation between the RHCP and the LHCP modes.