Dual-Band Multipolarized Aperture-Shared Antenna Array for Ku-/Ka-Band Satellite Communication

A dual-band multipolarized aperture-shared antenna array is presented, achieving Ku-band dual linearly polarized (LP) operation and Ka-band dual circularly polarized (CP) operation. Its dual-band aperture-shared structure is fed by two groups of independent feed networks, from the side and the bottom, using the quasi-planar coaxial waveguide line (QCWL) and the hollow-waveguide (HW) feed structure, respectively. The Ku-band antenna and Ka-band antenna are carried out through the same quad-ridge waveguide aperture and have the same array spacing. Thus, the large element spacing at high-frequency band inevitably leads to high sidelobes. The parasitic elements are adopted to suppress the high sidelobes in the E-plane and H-plane, and the realized gain of the high-frequency antenna is increased accordingly. In addition, a 1/ $2\lambda $ short-circuited stub is designed in the QCWL-based feed network for isolation enhancement. To demonstrate, a $4\times $ 4 element Ku-/Ka-band multipolarized antenna prototype is fabricated and measured. Experimental results show that the impedance bandwidths of 19.4% (14.4-17.5 GHz) for dual LP and 7.4% (32.5-35 GHz) for dual CP are achieved. The peak gains of the dual LP are 18.4 and 18 dBi, while those of the dual CP are 23.4 and 22.9 dBic.