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 was used to calculate the driving-point impedance of radial disk structure in circular groove guide. Non-uniform grid and triangular grid were used to approximate the curvilinear metal boundary of circular groove guide. And perfectly matched layer (PML) was applied to the open boundary of circular groove guide. Fine-grid was used to calculate the field's value in the radial disk in which we were interest. Discrete wave equation was used to update the tangential electric field value on the boundary of coarse- and fine-grid. At last, the driving-point impedances of the radial disk were 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 were achieved. Intuitional figures are helpful for the impedance matching in practice.A millimeter wave circular groove guide oscillator was designed and manufactured based on the analysis. At last, the testing system was established.Experimental results show that the oscillator can operate at 100.1GHz and 193μW .