An Analytic Method of Designing Broadband Oversized Waveguide Gradual TE01 Mode Bends

An analytic method for improving the working bandwidth of circular TE01 mode oversized waveguide bend is proposed by using the curvature-changing turning curve. The curvature-changing influence of the turning radius on the propagation of injected beam is investigated, and an optimum approach to control the coupling ability between the TE01 mode and the parasitic modes is deduced. Based on the analysis results, a Ka-band oversized waveguide gradual TE01 mode bend using the parabola as the turning curve is designed, manufactured, and measured. The transmission efficiency is over 96% in the frequency range of 23–48 GHz (the relative band is over 70.4%). The obtained radiation field patterns prove the high-purity outputs of the TE01 mode. In addition to high power and broadband, the proposed waveguide bend features a compact and simple structure and is easy to be machined.