An Integrated Dual-Band Dual-Circularly Polarized Shared-Aperture Transmit-Array Antenna for K-/Ka-Band Applications Enabled by Polarization Twisting Elements

An integrated dual-band dual-circularly polarized (dual-CP) transmit-array (TA) antenna operating at K- and Ka-bands is proposed. Antenna-filter-antenna (AFA) based polarization twisting TA cells possessing high cross-polarized and low copolarized linearly-polarized (LP) transmission characteristics are designed. These TA cells possess highly efficient circular-polarization transmission with flipped handedness without using any 180 degrees phase shifting lines, thus bringing about benefits such as symmetrical structures, design simplification, and more consistent circularly polarized (CP) transmission magnitudes. In addition, the dual-band dual-CP transmissive beamforming characteristics are realized by arranging K- and Ka-band cells in the same aperture and employing a hybrid phase compensation strategy. For reducing the overall device profile, right-handed CP (RHCP) and left-handed CP (LHCP) planar arrays operating at K- and Ka-bands are fabricated as feeds for the TA. A dual-band dual-CP TA antenna with independently controllable beam directions is synthesized and experimentally demonstrated. The measured 2-dB gain and axial ratio (AR) bandwidths are 11.7% and 10.2% for K-band RHCP and LHCP beams, and the two CP beams own bandwidths of about 7.5% at Ka-band. The proposed dual-band dual-CP TA antenna can be a promising candidate for satellite communications and so on.

Automated summary

This paper proposes an integrated dual-band dual-circularly polarized transmit-array antenna for K- and Ka-bands. Antenna-filter-antenna based polarization twisting TA cells are designed to achieve efficient circular-polarization transmission without using phase shifting lines. The dual-band dual-CP transmissive beamforming characteristics are realized by arranging K- and Ka-band cells in the same aperture and employing a hybrid phase compensation strategy. The measured results show that the antenna has independently controllable dual CP beams in K-band and Ka-band.