TM high order mode of rectangular double-gap cavity with a coupling slot in the center

The eigenfrequency and the characteristic impedance of π-TM high order mode of rectangular double-gap cavity with a coupling slot in the center are calculated by analytic method. The influence of sizes and the position of the coupling slot on the frequency and the characteristic impedance of π-TM mode are discussed. The results of the analytic calculation are compared with ISFEL3D simulation results, and it is shown that the analytic results are consistent with the simulation results on the whole, especially for the TM310 mode. Our research shows that the width of the coupling wall in double gap cavity has little influence, while the position and the sizes of the coupling slot have strong influence on the frequency and the characteristic impedance of π-TM modes. Meanwhile, it is found