Investigation of coaxial TE01 mode converter from high to low radius ratio structures

This paper investigates the characteristics of coaxial waveguide modes in variation to the cross-section geometry and proposes the solutions for broadband and high-purity conversions of lossless coaxial TE₀₁ mode at low terahertz-wave regime. Four-wave, eight-wave, and sixteen-wave rectangular waveguide power dividers/combiners are developed to excite the desired coaxial TE₀₁ mode but to suppress the potential parasitic TE₂₁, TE₄₁, and TE₈₁ oscillations at radius ratios 4.05, 1.64, and 1.36, respectively. Accordingly, the simulated results reveal the broad -1dB back-to-back transmission bandwidth of 13.5 GHz (14.3%), 12.7GHz (13.5%), and 18.7 GHz (19.9%) at W-band. Notably, these three converters with different cross-sections are designed to be capable of concentric integration, which yields a three-channel (3C) high power rotary joint for long-range and high-resolution radar applications.