Zhengxiang Luo

Development of Integration HTSC Linear Phase Filter With External Equalization

A variety of miniature half-wave multizigzag resonators was given, and an eight-pole high-temperature superconductor (HTSC) quasi-elliptic filter with no cross-line was developed with these resonators. In this paper, a novel single-pole group delay equalizer was also given to flatten a nonlinear phase quasi-elliptic filters phase, which solves the tuning difficulty of the HTSC linear phase filter. Moreover, it cannot only ensure that the finished HTSC filter has a good linear phase characteristic but also solve the integration of the linear phase filter with external equalization. Finally, on YBCO/LaAlO3/YBCO substrate with the dimension of 31.6 mm × 29.2 mm, a miniature eight-pole HTSC quasi-elliptic linear phase filter using external equalization is developed, where the center frequency is 2250.84 MHz, the bandwidth is 14 MHz, the best insertion loss in passband is 2.09 dB, and the return loss is better than 18.97 dB, as per measurements. In passband, the measured group delay response has a good agreement with the simulated response, and its variation is less than 50 ns over 78.5% of the filter bandwidth.

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.