This paper presents the field test of our first demonstration cluster with five base stations (BTS) on code division multiple access (CDMA) wireless communication in China, while each BTS was installed with a high temperature superconductor (HTS) receiver. The HTS receivers have the same centre frequency of 830 MHz, a bandwidth of 13 MHz, and a noise figure (NF) of 0.9 dB. After the conventional receivers in the BTSs were replaced by the HTS receivers, a consequent drive test was carried out. A 2.35 dB decrease of the mean mobile transmit power was observed in the demonstration cluster.HTS filter, demonstration cluster, HTS receiver, CDMA, field test Microwave filters made up of high temperature superconductor (HTS) thin films are widely studied in many countries. Due to the very low surface resistance of HTS thin film in microwave frequency, HTS filter shows an excellent performance with both sharp skirt and very low insertion loss [1,2] . Therefore, it can be used to greatly improve the sensitivity and selectivity of wireless receiver systems. Many applications of HTS filters have been reported, such as in wireless communication system [3] , astronomical telescope [4] , digital Television system [5] , and so on. The Superconductor Technologies Inc. (STI), a company in United States, has reported their applications of a large amount of HTS filters in wireless communication base station (BTS) systems.We have reported our first HTS filter for GSM communication system [6] and our first field trial of HTS receiver on a single code division multiple access (CDMA) BTS [7,8] . In this paper, we present the field test of our first demonstration cluster with five CDMA BTSs of China Unicom Corporation, which is one of the largest wireless communication operators in China. Each BTS of the demonstration cluster was installed with an HTS receiver. After the installation of HTS receivers in the demonstration cluster, a consequent drive test was conducted, and an obvious decrease of mobile handset's mean transmit power was observed. Thus far, all the HTS receivers in the demonstration cluster have been operating stably for more than 18 months.We manufactured five HTS receivers with the same performance and installed them on the five BTSs in the demonstration cluster. The drive tests were carried out by Tsinghua University with support of China Unicom, Beijing Branch. HTS filter systemThe HTS receiver for the CDMA BTS consists of six HTS channels, a vacuum cavity, a mini-type stirling cooler, and electrical controller circuits. Each channel in the HTS receiver includes an HTS filter and a cryogenic low noise amplifier (Cryo-LNA), which both operate at a temperature of about 70 K. The HTS band-pass filters, the key component of the HTS receiver, were designed and manufactured using YBCO thin films on 2-inch MgO or sapphire substrates individually. Each HTS filter has the characteristics of center frequency of 830

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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This article presents a six‐pole high‐temperature superconducting (HTS) filter at 2.5 GHz with a compact size of 10 mm × 15 mm on MgO substrate. Twin‐spiral resonators with high simulation accuracy are used in the design procedure. EM simulations verify that the filter response is insensitive to the variations of the cell sizes and the substrate parameters. The untuned measurement of the HTS filter at 70 K shows a high performance. The minimum return loss is 14.7 dB without any tuning. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 141–144, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24018

A novel high temperature superconducting (HTS) filter with split‐end stepped impedance resonators (SIR) is developed on MgO substrate. Spiral feedlines are used to meet the requirement of the external quality factor. A quarter‐wavelength (λ/4) spiral stub is introduced at the input feedline to provide additional transmission zeros at the high frequency end, which can improve both the out‐of‐band rejection and band‐edge steepness. The measured results at 70 K are in good agreement with the simulated ones. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2455–2457, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23688