Wideband dual-mode monostatic simultaneous transmit and receive antenna system

A novel wideband monostatic simultaneous transmit and receive (STAR) antenna system based on eight-arm equiangular spiral aperture is proposed. The eight-arm STAR spiral is configured such that four arms are used for transmitting and the other four arms for receiving. The multi-mode characteristics of the four-arm spiral aperture along with applied excitation enable high TX/RX isolation for diverse circular-polarization modes of radiation (i.e. broadside and split-beam modes). The operational principles of the proposed system are discussed and the feasibility thereof is demonstrated computationally and experimentally. System isolation >40dB is obtained over 8:1 bandwidth for different modes of operation while maintaining similar high-quality TX/RX radiation characteristics.