Shirong Bu

Development of miniature HTSC microwave bandpass filter with multi-zigzag line structure

On YBCO/LaAlO3/YBCO substrate with the dimension of 10 mm × 20 mm, a miniature HTSC (high temperature superconductivity) bandpass filter with multi-zigzag line structure is developed. At 77 K, the center frequency is 1.2 GHz, the bandwidth is 50 MHz, and the insertion loss is 0.12 dB.

A new design of compact microstrip Wilkinson power dividers

A novel compact microstrip Wilkinson power divider with an easy design and fabrication is proposed in this paper. Through capacitive or inductive loading of both of the quarter-wave transmission lines and the isolated resistor employed in conventional Wilkinson power dividers, reduction of the transmission line segments from λ g /4 to λ g /30 is obtained. Therefore, the proposed structure can distinctly save the occupied area. Furthermore, some useful design equations based on odd-even mode analysis for the proposed circuit model are introduced to provide an accurate method to design compact Wilkinson power dividers. The fabricated power divider designed for the frequency of 800MHz is 84% smaller than conventional ones, and has a 120MHz bandwidth for which the input return loss is better than 20-dB. Within this bandwidth, the insertion loss is less than 0.3-dB and the isolation between the outputs more than 20-dB.

Neural-Network-Based Approach for Extracting Eigenvectors and Eigenvalues of Real Normal Matrices and Some Extension to Real Matrices

This paper introduces a novel neural-network-based approach for extracting some eigenpairs of real normal matrices of order n. Based on the proposed algorithm, the eigenvalues that have the largest and smallest modulus, real parts, or absolute values of imaginary parts can be extracted, respectively, as well as the corresponding eigenvectors. Although the ordinary differential equation on which our proposed algorithm is built is only n-dimensional, it can succeed to extract n-dimensional complex eigenvectors that are indeed 2n-dimensional real vectors. Moreover, we show that extracting eigen-pairs of general real matrices can be reduced to those of real normal matrices by employing the norm-reducing skill. Numerical experiments verified the computational capability of the proposed algorithm.

Compact evanescent mode waveguide duplexers

Evanescent mode waveguide duplexer with coaxial posts and irises coupling sections was presented in this article, and the unload Q factor and power carrying capacity were discussed. Such duplexers are suitable for some integrated systems having volume constraints. One design example simulated by Mode Matching Method was also given. Example duplexer with total 14 sections having upper stopband widths of up to five times the fundamental bandpass center frequency was presented. The center frequencies of two passbands were 1.87 GHz and 2.09 GHz, and the corresponding fractional bandwidth were 6.9% and 7.7%. The insertion losses in both passband were 0.8 dB. With the irises coupling structure which was used to shrink the longitudinal dimension especially for narrow bandwidth devices, the volume of this duplexer was 183 × 30 × 17 mm3, it was 1/5 of its conventional duplexer.

Application of High Temperature Superconductor Technology in a UHF Digital Trunking Communication System

In this paper, the application of high temperature superconductor technology in a UHF digital trunking communication system is introduced. The results of the experiment indicated that HTSC (high temperature superconductor) technology can improve the digital sensitivity of the base station more than 6dB in the complex electromagnetic environment, which equals that the coverage radius of base station is improved about twice, that is to say, the coverage area can be extended to four times.