Planar Dual-Mode Dipole Antenna Formed by Artificial Microstrip Arms Loaded With Multiple H-Slots for Broadband Operation of Vertically Polarized Radiation on UAV Platform

An antenna design is presented for long-distance transmission in the unmanned aerial vehicle (UAV) application. This antenna is in a dipole configuration but with dual-mode operations of both dipole and monopole mechanisms. The monopole behavior becomes apparent when installed on the UAV platform to provide a large ground. To ensure both modes’ good integration to produce a broad bandwidth, the dipole arms are formed by H-slot loaded microstrips to create a slower phase velocity. The separation between adjacent harmonic resonances can be decreased. This antenna has good vertically polarized radiation and maximum gains near the horizontal plane to provide better long-distance connections. Various combinations of H-shaped slots are applied to examine the bandwidth behaviors. The achieved size is 90 mm, roughly 1/3 wavelengths at 1.25 GHz and 1/4 at 0.8 GHz. The bandwidth is larger than 50%. Numerical HFSS full-wave simulation and measurement results are compared to validate the feasibility.