Gong Shuxi

Microstrip fractal patch antenna for multi-band communication

A novel square microstrip fractal patch antenna in a Sierpinski carpet is proposed for three-band operation. Theoretical analysis and measurement of the antenna are carried out. This antenna is an attractive candidate for wireless, satellite and mobile communication applications.

Design of a wide-band Yagi-Uda antenna using differential evolution algorithm

This paper presents a wide-band Yagi-Uda antenna with X-shape driven dipoles and parasitic elements using differential evolution algorithm (DE). In the optimization process, a method of moments code, NEC code simulates the antenna designs generated by DE. In order to illustrate the capabilities of the method, a nine-element Yagi-Uda antenna is given. The measured and simulated impedance bandwidth of VSWR<1.8 reaches 19.0%, which is three times the bandwidth of the Yagi-Uda antenna using a dipole driven element. The maximum gain over the operating frequency band is 12.7dB. The results are compared with Nelar Mead method in an equally spaced array design.

Complex Rays Expansion of Three Dimension Radiation Pattern Using Buckyball Grid

The method of complex rays expansion of three dimensions radiation pattern is proposed basing on the Gauss characteristic of the paraxial far fields from complex source. The Gauss beams shooting from the origin to the gird nodes of the Buckyball distribute uniformly in all directions. The effect of the parameters of beam width and discrete interval to the simulation of pattern are analyzed, and the experiential choices of the parameters are given. The simulative results show a high simulative precision.

Improvement on the Forward-backward Iterative Physical Optics Algorithm Applied to Computing the RCS of Large Open-ended Cavities

The method of initial value succession is introduced to the forward-backward iterative physical optics (FBIPO) algorithm. The initial residual error is reduced by inheriting the current values. Combined with a relaxation parameter, the method improves the convergence of the FBIPO algorithm for cavity scattering problems. The accuracy of RCS calculation is also enhanced by using a more precise mixed-face model. Then, the RCS of a jet inlet model is calculated, with its results in good agreement with the experimental ones. The method is also used to calculate the RCS reduction of a circular waveguide by coating the inner wall with a thin absorber layer.

Design of a shaped beam base station antenna using genetic algorithm

Genetic algorithm is used to optimize a base station antenna in order to achieve a shaped beam in a frequency band. During the optimization process, different antenna models have been evaluated using the Method of Moment (MoM). As a result of this optimization, a shaped beam antenna with suppressed sidelobe smaller than −18dB, backlobe smaller than −30dB and filled null point larger than −15dB is achieved. The proposed method is closer to reality compared with previous methods and can be used to optimize complicated antennas. The result is very useful for engineering and theoretical analysis.

A combined full-wave BCG-FFT method for radiation of microstrip antenna arrays

A method of combining BiConjugate Gradient(BCG) with Fast Fourier Transform(FFT) to analyze the radiation of microstrip antenna arrays is presented, where the spatially discrete BCG-FFT for analyzing microstrip structure is used and the del operators on Green’s functions are transferred from the singular kernel to the expansion and testing functions. The resultant equations are solved by using BCG method in which the matrix-vector product is evaluated efficiently with FFT. The calculated patterns are in good agreement with the measured data.

New expressions for equivalent edge currents

It is known that the results of the incremental length diffraction coefficients (ILDC) (Mitzner 1974) and the method of equivalent edge currents (MEC) (Michaeli 1984) differ by terms due to the physical optics (PO) current. These PO components become infinite for certain aspects of observation and illumination, by the extraction of the PO contribution from MEC. ILDC, unlike MEC, predicts finite currents for certain directions of observation. However, as already observed by Mitzner, ILDC also displays infinities for certain combinations of observation and incidence directions, though the range of singular aspects is reduced in comparison with MEC. Michaeli (1986) derived a set of expressions for the fringe current components of the equivalent edge currents, those expressions are finite for all aspects of illumination and observation, except for the Ufuntsev singularity. However, for certain non-singular aspects of the ILDC expressions, there is a wide divergence between Michaelis (1986) results and Mitzners results. In this paper, new expressions are derived for the fringe current components of equivalent edge currents, which are advantageous over those of Mitzner and Michaeli in both accuracy and versatility. A numerical example of the bistatic RCS of a square plate is given.