The Tilted-Branch Comb-Structure and Its Application to Beam Switchable Antenna in Wideband for Indoor Wi-Fi Communication

This paper investigates the radiation characteristics of tilted-branch comb structures and proposes a novel beam-switchable antenna design capable of switching between high-gain horizontal omnidirectional and vertical directional end-fire radiation patterns. Compared to conventional comb-structure-based reconfigurable antennas, the proposed design achieves improved beam-direction stability (0.25∘/100 MHz), while extending high-gain radiation coverage across the 5.1-5.9 GHz band, targeting indoor Wi-Fi applications. The antenna configuration integrates two 0.5kg comb structures with inversely tilted branches and a straight-line structure, interconnected through dual phase modulation networks. Under even-mode operation, the combined tilted-branch comb structures exhibit stable broadband non-frequency-scanning characteristics with less than 2∘ beam-pointing fluctuation over the 5.1-5.9 GHz range for horizontal omnidirectional radiation. Complementary patches are introduced to enforce odd-mode operation in both comb structures, enabling directional end-fire radiation in the vertical plane. A prototype featuring a compact integrated DC bias circuit for direct beam switching was fabricated and experimentally validated. The system demonstrates stable horizontal omnidirectional radiation (θ = 90∘-94∘) and vertical directional end-fire radiation (θ = 0∘) within an overlapping frequency range of 5.1-5.9 GHz (14.65%), with measured gains of 6.0-7.6 dBi and 5.0-5.7 dBi, respectively. Experimental validation demonstrates the designs ability to maintain stable radiation characteristics while addressing dual-coverage requirements in complex indoor environments.