The paper reports on advances in the development of high temperature superconducting 40 MHz bandwidth fourpole bandpass filters with elliptic frequency response for 3.4 -4.2 GHz (extended C-band) output multiplexers of communication satellites. By employing the concept of "edgecurrent-free" disk and ring resonators the filters possess a small size but can handle 60 W transmitted power with sufficiently low insertion loss and intermodulation. Measurements of the unloaded Q-factor and power handling as function of the temperature, performed at single disk resonators made from YBa2Cu307.p on LaA103 and sapphire substrates indicate the conditions under which the required Q-factor of about 1.5.105 and sufficiently low nonlinear response up to an oscillating power of 15 kW can be obtained. Approaches for shifting the resonant frequencies of unwanted modes relative to the resonant frequency of the employed TMolo-mode are outlined and shown to be necessary for the envisaged multiplexer applications.
This paper presents the field trial results of a high temperature superconductor filter system (HTSFS) in a code division multiple access (CDMA) mobile communication base station (BTS) in Tangshan, China.The center frequency of the HTSFS is 830 MHz with 1.4% fractional bandwidth. The noise figure (NF) of the HTSFS, including connectors and cables, is 0.8 dB. The field trial results show that after the HTSFS was installed in the receiver front-end of a CDMA base station, the transmitting power of handset was decreased by 3.1 dB on average. Up to now, the HTSFS has been running steadily in the base station for more than 22 months, demonstrating the reliability and stability of the system.
HTS, filter, mobile communication, LNAIn recent years, the rapid growth of the mobile communication in China [1] urges the wireless network operators to do their best to optimize the mobile communication system. The excellent performance of HTSFS can greatly improve the receiving sensitivity and selectivity of the BTS, leading to an increase in the capacity, coverage and ability of anti-interference of the mobile communication network. So the HTSFS has become a competitive resolution for wireless communication companies [2][3][4][5][6] .At present, thousands of HTSFSs are used in wireless communication BTSs in USA. The HTSFSs have proved their advantages over the conventional ones [7] . In this paper, we presented the results of the first field trial of our HTS filters in a CDMA mobile communication BTS of China.
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