Jin-Lin Hu

A new temporal basis function for the time-domain integral equation method

A new temporal basis function that has all-order continuous derivative has been constructed using a nonlinear optimization scheme. This new basis function provides a much more stable explicit marching-on-in-time (MOT) solution, based on the time-domain integral equation (TDIE) method, than that presently available. Two examples are presented to illustrate the superior stability of the proposed temporal basis function.

Synthesis of shaped-beam pattern for mobile antenna

In a mobile communication system, the base station antennas are often required to radiate shaped-beam patterns, which have as low a level as possible toward the interference zone where the same frequency is used and, conversely, have as high a level as possible toward the service zone. So, the synthesis of the shaped-beam pattern is one of great importance to designing the base station antennas. We present a new synthesis method of the shaped-beam pattern by controlling only the excitation phases of the array elements. We first apply array theory and optimization theory to construct an objective function. Then, we employ the quasi-Newton method to minimize this nonlinear problem. Two synthesis examples based on the 16-element linear arrays are presented to demonstrate the efficiency of our method.

RCS computation of jet engine with complex termination based on multiplaten Z-buffer algorithm

The analysis of electromagnetic scattering from the jet engine with complex termination is a very difficult task because the electrical size of the engine cavity is very large and the geometry of engine termination is very complex. In this paper, the shooting-and-bounding rays (SBR) method is employed to analyse electromagnetic scattering from jet engines with complex termination. In order to accelerate the ray tracing and to economise the computation memory, the multiplaten Z-buffer algorithm is employed to model the jet engine. Two jet engine models with the complex termination are analysed. Excellent results are obtained for the two models.

Novel approach to construct temporal basis functions for time-domain integral equation method

Time-domain integral equation (TDIE) methods, for the solution of transient electromagnetic problems have steadily increased in popularity. A novel construction method is presented to design the new temporal basis function. We first specify the principal properties of the desirable temporal basis function. According to these properties and choosing a suitable function with some parameters, we construct a nonlinear programming problem with respect to these parameters, from which the new temporal basis function can be derived. The obtained temporal function has the any-order continuous derivative and is not a truncated version of any function. By using the construction method, a new temporal function, namely, the rational fractional temporal function, is also presented. The numerical result shows that the new temporal function pushes the occurrence of the late-time instability of the transient simulation further down in time when compared to the previous temporal functions.

Design of linearly fed shaped-beam-pattern microstrip antenna array

An 8-element shaped-beam pattern microstrip antenna array for the base station of mobile communication system has been designed. A cosecant pattern in the main beam which allow a constant power distribution in the service zone is achieved by feeding linearly varied amplitudes and phases into the elements of the array. The array operates at 27.5 GHz and at an angle of about 20/spl deg/ from the broadside is obtained. The side lobes are in the order of -10 dB and cross-polarization level about 20 dB.

A fast iteration technique for 2D perfect conducting cylinder scattering

A novel fast iteration technique, based on the interaction between matrix decomposition by the measured equation of invariance (MDMEI) and the method of moments (MoM), is presented. The new iteration can accelerate the MoM iteration process. A numerical example for the scattering of 2D perfect conducting rectangular cylinders with a circumference of 96 wavelengths shows that the computation speed can be increased by up to 2.5 times.