Study on Reconfigurable Coaperture Antenna Arrays Based on Time-Modulation and Retrodirective Techniques

Time-modulation (TM) technique for array design is opening the way for the development of easy-reconfiguration, low-complexity, and high-accuracy antenna systems for modern wireless applications. In this study, four different scenarios of TM-based reconfigurable coaperture antenna arrays are introduced. The aims are to make use of the common antenna elements for the coaperture and to share the RF switches needed in TM technique to form the reconfiguration. For the reconfigurable functionality, the retrodirective (RD) technique is involved, and for the reconfigurable band, the synthesized transmission line (STL) technology is involved. Four proposed arrays are single-band time-modulated retrodirective and self-null-steering array (i.e., single-band TM-RDNA), single-band time-modulated/retrodirective/time-modulated retrodirective array (i.e., single-band TM-RDA), dual-band TM-RDA, and triband TM-RDA. In the single-band TM-RDNA, a frequency offset, which is equal to the TM frequency, between two time-modulated phase conjugators is introduced to realize the array capable of RD and self-null steering simultaneously at retransmitted frequency. In the single-, dual-, and triband TM-RDAs, the introduced TM-RDA functions as a low sidelobe RDA at carrier frequency, and as an extra benefit, it can function as a low sidelobe RDA at harmonic frequencies. The features, superiority, and inferiority of these TM-based reconfigurable coaperture arrays are discussed and summarized. To experimentally verify the feasibility of the proposed schemes, a four-element single-band TM-RDNA and single-band TM-RDA structures are constructed and tested.