A waveguide magic tee at W band is analyzed exactly and developed. The analysis approach is a combination of the mode expansion method and finite element method,whic h is based on the weak form of Helmholtz equation. Mode expansion instead of PML (Perfectly Matched Layers) is used to truncate the computing space of finite element. A magic tee at W band (75∼110 GHz) with the structure,whic h is easy for manufacture,is developed. Calculated results are presented and compared to those in experiments. Agreement has been observed. A sensitivity analysis is carried out, which shows the influence of the tolerance of manufacture on the performance of the magic tee. And the power carrying capacity of the designed magic tee is also evaluated.

Field structures of waveguide Y -junction circulators containing irregular shaped ferrite material,suc h as Y -junction with partial-height cylinder/triangle ferrite posts and metal step impedance transformer, Y -junction with a ferrite sphere, and dual higher order modes circulator,whic h are classified as different junction resonance modes, are depicted to illustrate the circulating process. The analysis method used is a combination of the mode expansion method and finite element method,whic h is based on the weak form of Helmholtz equation. Calculated results (return loss,insertion loss and isolation) of these structures are shown and compared respectively to those in literatures. Consistencies have been observed.

It is a difficulty problem to measure permittivity of a dielectric material accurately whose permittivity is very close to unit. Open cavity method and interferometer method have been used in the past. In this paper, the sensitivity of these two methods to a small disturbance of permittivity is simulated and compared. Based on the simulation a new approach combining merits of the open cavity method and the interferometer method is proposed, and its advantages are described.

A novel diffraction lens quasi-optical monopulse antenna/feed is proposed and analyzed using finite-difference time-domain (FDTD) method. The structure consists of diffraction lenses, a quasi-optical sum- difference network, matching lenses and horns connecting waveguide. This antenna structure is novel, low-loss and compact and may be designed to be polarization-independent. Owing to its low absorptive loss and relative easy for manufacturing, this monopulse antenna/feed structure is suitable for millimeter wave and submillimeter wave application. The parameters of the structure are selected to some extent to get better performance. Calculation results are presented to show its properties.

In this paper the frequency dependence and focusing performance in focal plane of a diffractive lens is analyzed by FDTD method at millimeter wavelengths. Binary lens and four-level lens are onsidered. The field distribution on the focal plane of the diffractive lens for the incident wave at different frequency is presented, which shows the frequency dependence and focusing performance of the lens.