Design of a rectangular waveguide to cylindrical cavity mode launcher for TE₀₁₁mode with maximum quality‐factor

Abstract

This article presents the design of a mode launcher for launching TE011 mode in a cylindrical cavity. In the given design, TE011 mode is excited from the top wall of the cylindrical cavity using a rectangular waveguide. This type of top wall excitation of the cavity has been used keeping in view the application of the proposed launcher in coupling analysis of a coaxial magnetron. The proposed design is verified by launching TE011 mode in a cylindrical cavity, which is designed to operate at 9.3 GHz with the maximum quality factor. The value of quality factor obtained analytically is 31 030 and the same is verified by comparing it with simulation results obtained from CST and HFSS. Return loss and insertion loss of the mode launcher are obtained as 40.24 and 0.12 dB at 9.3 GHz, respectively. The frequency tunability of the cavity is also studied by changing the length of the cavity by making the bottom wall movable and a tuning range of 200 MHz is achieved. Performance of the top wall excitation is also compared with the conventional TE011 mode excitation from the rectangular waveguide through the side wall of the cavity, and both are in good agreement.

Calculation and Analysis of Characteristic Parameters for Lossy Resonator

“…At first, area 1 was considered as a typical circular waveguide [26] and regions 2 and 3 were regarded as circular waveguides filled with a lossy dielectric. For a specific mode, the change of electric field and magnetic field in the φ direction should be the same for all 3 regions.…”

Cylindrical Multimode Waveguides as Focusing Interferometric Systems

“…Photonic crystal waveguides enable realization of integrated versions of such systems. − Mode interference has also formed the basis for beam-steering applications in antenna arrays . Mode converters and launchers are used to couple between waveguide and free space modes or different types of waveguide modes . For example, in gyrotrons, quasi-optical mode converters are used to convert higher-order waveguide modes of gyrotron oscillators into a Gaussian field distribution .…”

“…19 Mode converters and launchers are used to couple between waveguide and free space modes or different types of waveguide modes. 20 For example, in gyrotrons, quasi-optical mode converters are used to convert higher-order waveguide modes of gyrotron oscillators into a Gaussian field distribution. 21 A commonly used type of mode converters is the Vlasov launcher, 22 which consists of a stepped-cut cylindrical Vlasov launcher, an elliptical and a parabolic reflector, and can be designed using ray-optical calculations.…”