The Study On Circular Groove Guide Oscillator

Circular groove guide is a new type of transmission medium which was firstly introduced by Hong-sheng Yang et al. Compared with the conventional guides (circular guide and rectangular guide), circular groove guide has some attractive advantages, such as low loss, low dispersion, large structural dimension, higher power handling capacity, this gives an alternative to design the millimeter wave and sub-millimeter wave components.With the rapid development of millimeter wave solid device, millimeter wave circuit and system are bound to use solid device. Among the solid components, Gunn and IMPATT are most commonly used. Circular groove guide resonate cavity and Gunn device were chosen to make a millimeter wave oscillator.In this paper, Finite-difference time-domain (FDTD) method is used to calculate the input impedance of post mount structure in circular groove guide. The relations between position of post mount and input impedance were obtained by the FDTD method. More discussion about radial disk was given based on these analysis. Non-uniform grid and triangular grid are used to approximate the curvilinear metal boundary of circular groove guide. And perfectly matched layer (PML) is applied to the open boundary of circular groove guide. Fine-grid is used to calculate the field's value in the radial disk in which we are interest. Discrete wave equation is used to update the tangential electric value on the boundary of coarse- and fine-grid. At last, the driving-point impedances of the radial disk are obtained from the ratio of the Fourier transform of the voltage to the Fourier transform of the current. By changing the characters of the radial disk, the input impedance figure related to the diameter, thickness and position of the radial disk are gotten.A millimeter wave circular groove guide oscillator is designed based on the analysis. At last, the testing system and testing process are discussed.