K-/Ka-Band Shared-Aperture Phased Array With Wide Bandwidth and Wide Beam Coverage for LEO Satellite Communication

A K-/Ka-band shared-aperture endfire phased array antenna is presented in this article. The antenna has the properties of dual wide bandwidths, orthogonal circular polarizations (CPs), wide beam coverage, and high isolation between the K-band and Ka-band channels. In this work, a new array topology is proposed to enhance the design freedom and the periodicity of the antenna array. Then, the filtering structures used to reflect the crossband coupled power also enhance the isolation between the K-band and Ka-band channels. The crossband mutual coupling is reflected and reradiated to generate the wideband CP beams. The high-order parallel plate waveguide (PPW) mode is suppressed to realize the wide CP beam coverage. The working bands at the boresight are 17.7–21.2 and 27.5–31.0 GHz, respectively. The polarizations are right-hand CP (RHCP) in K-band and left-hand CP (LHCP) in Ka-band. The maximal scan angles are ±60°. The axial ratios (ARs) are below 3 dB at boresight and below 5 dB when the beam scans to ±60°. The isolation between the K-band and Ka-band channels is higher than 40 dB.