Bidirectional Scanning Antenna Based on Surface Wave Mode

A bidirectional scanning antenna (BSA) based on surface wave mode is proposed. The bidirectional scanning capacity is achieved by two back-to-back placed frequency scanning tapered slot antenna (FSTSA) elements. The corrugated slot array in inner edges enables the BSA to support two surface wave modes to propagate along the inner edges with different phase constants. Due to the dispersion characteristic of surface wave mode, the phase difference between two modes varies with frequencies, then frequency scanning is achieved at the endfire. Slot arrays are also etched on the outer edges to reduce current flowing. By separately configuring two back-to-back FSTSA elements, the BSA could form a rotationally symmetrical, mirror symmetrical, or asymmetrical bidirectional scanning pattern. Three prototypes with rotationally symmetrical, mirror symmetrical, and asymmetrical pattern are designed and fabricated to verify the principles. Since the scanning plane is parallel to antenna surface, the proposed BSA has a low cross section, which makes it suitable for wireless communication in tunnels and coal mines where good air ventilation is required.