Compact Surface-Wave Assisted Beam-Steerable Antenna Based on HIS

The concept of taking surface wave as an assistant role to obtain wide beams with main directions tilting to endfire is introduced in this paper. Planar Yagi-Uda-like antennas support TE₀ surface wave propagation and exhibit endfire radiation patterns. However, when such antennas are printed on a thin grounded substrate, there is no propagation of TE mode and beams tilting to broadside. Benefiting from the advantage that the high impedance surface (HIS) could support TE and/or TM modes propagation, the idea of placing a planar Yagi-Uda-like antenna in close proximity to a HIS to excite unidirectional predominately TE surface wave in HIS is proposed. Power radiated by the feed antenna, in combination with power diffracted by the surface wave determines the total radiation pattern, resulting in the desired pattern. For verification, a compact, low-profile, pattern-reconfigurable parasitic array (having an interstrip spacing of 0.048 λ₀) with an integrated DC biasing circuit was fabricated and tested. Good agreement was obtained between measured and simulated results.