Full Duplex Filtering Antenna with Nonreciprocal Transmission Characteristic Using SIW and Spatiotemporal Modulation

Full duplex (FD) filtering antenna with nonreciprocal transmission characteristic, implemented by substrate integrated waveguide (SIW) integrated with spatiotemporal modulation (STM) method, is proposed. The design features three input/output ports: transmitting (Tx), receiving (Rx), and antenna (Ant). It consists of three 120° fan-shaped SIW cavities that are coupled in a delta topology through electric-magnetic coupling structures, thereby forming a stable second-order filtering response for each transmission channel created by two adjacent SIW cavities. Three STM signals of the same amplitude and frequency, but with a progressive 120° phase difference, are applied to the non-linear capacitors placed on the EMC structures, resulting in the formation of a filtering circulator. Additionally, a radiation slot antenna is etched on the top layer of the SIW cavity of the Ant port, enabling the radiation function. This design seamlessly integrates the functions of a bandpass filter, a circulator, and an antenna into a single, integrated device.