Gap-coupled and Hybrid-coupled Half Hexagonal Microstrip Antennas for Dual Frequency Operations

This paper presents two configurations of compact half hexagonal microstrip antennas (HHMSA) employing gapcoupled and direct and gap coupling techniques to achieve dual band performance. Extensive parametric studies on the effects of feed point location and coupling gap have been conducted through simulations and practical experiments, yielding accurate results. For the HHMSA with feed along y-axis, dual frequency ratios ranging from 1.047 to 1.075 for gap-coupled and 1.186 to 1.295 for hybrid-coupled HHMSA were achieved by varying the size of the parasitic antenna. In the HHMSA with feed along x -axis, frequency ratios varied from 1.115 to 1.174 for gap-coupled and 1.217 to $\mathbf{1 . 3 3 7}$ for hybrid-coupled HHMSA. Optimization of the feed point and strip width for direct and gap coupling was crucial in achieving better resonance. These findings demonstrate the potential for tuning dual band performance in HHMSA through precise control of geometric and coupling parameters. The simulated results are validated experimentally.