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He L.J.,Tianjin University of Technology | Ji L.Y.,Tianjin Hi Technology Superconducting Electronic Co. | Du J.C.,Tianjin University of Technology
Advanced Materials Research | Year: 2013

This paper represents a high-temperature superconducting (HTS) linear phase filter with self-equalization for WCDMA communication system. of the filter have been presented. The principle, equivalent model, theoretical result, coupling matrix, and the simulated result have been presented. The desired filter with 12-pole and 2 cross couplings has a center frequency of 1950 MHz. The measurement results show that the response of practical filters is in good agreement with that of simulated results and theoretical analysis, the group delay variation is less than ±10 ns over 75% of the filter bandwidth. © (2013) Trans Tech Publications, Switzerland.


Gao W.,Tianjin University of Technology | He L.,Tianjin University of Technology | Ji L.,Tianjin Hi Technology Superconducting Electronic Co.
Advanced Materials Research | Year: 2012

A three-channel high temperature superconducting filter is designed for channelized receiver front-end systems. The principle and equivalent model of the filter has been demonstrated. There is 6-pole for each channel of the desired three-channel filter. The bandwidth of each channel is 40MHz.The simulation result is good agreement with theoretical analysis, illustrating the feasibility of this design. Such a structure of high temperature superconducting filters will have a wide application in communication fields © (2012) Trans Tech Publications, Switzerland.


Ji L.,Tianjin Hi Technology Superconducting Electronic Co. | Ma J.,Tianjin Hi Technology Superconducting Electronic Co. | Ma J.,Hebei University of Technology | Sun J.,Tianjin Hi Technology Superconducting Electronic Co. | And 3 more authors.
Science China Information Sciences | Year: 2012

In this paper, a dual-band high temperature superconducting (HTS) filter with 14-pole and 3 cross couplings is presented. The equivalent model, theoretical result, coupling matrix, and the simulated result of the filter are demonstrated. The desired filter is designed and fabricated using double-sided DyBa 2Cu 3O 7 thin films on MgO wafer 2 inches in diameter and 0.5 mm in thickness. The filter has two passbands with frequencies 1920-1940 MHz and 1960-1980 MHz respectively, and insertion loss less than 0.2 dB. The measurement results show that the response of practical filters is in good agreement with that of simulated results and theoretical analysis, with the group delay variation being less than ±20 ns over 90% of the filter bandwidth for the two passbands. © 2011 Science China Press and Springer-Verlag Berlin Heidelberg.


Du J.C.,Tianjin University of Technology | Ji L.Y.,Tianjin Hi Technology Superconducting Electronic Co. | He L.J.,Tianjin University of Technology
Applied Mechanics and Materials | Year: 2013

A high-temperature superconducting(HTS) band-pass filter centered frequency at 127.5MHz was successfully designed and developed. The HTS filter is 14-pole, adopting compact symmetrical dual-spiral resonators. The filter was fabricated on a 3-inch-diameter 0.5-mm-thick LaAlO3 wafer with double-sided DyBa2Cu3O7 thin films. Through the low temperature test, the insertion loss of the HTS filter is under 0.1dB, the bandwidth is 20 MHz, the return loss is better than -22dB and the out-of-band rejection is greater than 80dB. The filter's measurements agree well with the simulation. © (2013) Trans Tech Publications, Switzerland.

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