Design Approach of Radiation Pattern Reshaping for TM12 Mode and Its Application in Bandwidth Enhancement

Abstract

An approach for the radiation pattern reshaping for TM₁₂ mode is proposed in this communication. Initially, the working principle is theoretically investigated by far-field calculation. It demonstrates that by decreasing two key factors, <inline-formula> <tex-math notation= LaTeX >$n$ </tex-math></inline-formula> and <inline-formula> <tex-math notation= LaTeX >$W/\\lambda $ </tex-math></inline-formula>, the radiation of TM₁₂ mode could be effectively transformed into the broadside type without sidelobes. Thus, after combining with the fundamental TM₁₀ mode, the proposed approach is well suited for dual-band or wideband applications. Finally, a wideband prototype is designed, fabricated, and tested. The simulated and measured results are found to be in good agreement with each other, illustrating that the proposed antenna simultaneously achieves compact dimensions, wide bandwidth (18.6%), stable broadside gain (8.55–10.07 dBi), and low cross polarization (−22 dB).