Phased Array with Switchable Dual Circular Polarization Based on Subarray for Low-Cost LEO Satellite Communication

In this paper, a low-cost K-band phased array antenna is designed for LEO satellite communication. The design reduces the number of T/R components by allowing multiple elements to share a single T/R channel, thereby significantly lowering the overall cost. To facilitate subsequent integration and testing, modular constraints are imposed on the subarray topology. In this implementation, large-scale phased arrays are constructed by stitching together four modular subarrays. The phased array is further designed to support switchable dual circular polarization (CP) states, enabling compatibility with diverse satellite communication networks. By analyzing the phase center variations caused by different internal element arrangements, the configuration that best aligns with the geometric center is selected. A simulation method for large-scale radiation performance is established by evaluating inter-array coupling. To validate the proposed design, a 256-element low-cost phased array is fabricated and measured across the entire frequency band. A near-field calibration strategy is also developed for this new array architecture. Measurement results show that within a ±45° scanning range, the phased array achieves sidelobe levels below –10 dB and maintains an axial ratio below 3 dB across the full operating bandwidth, demonstrating excellent radiation performance and CP characteristics.