CDMA移动通信用高温超导滤波器的研制

本文提出了一种新型H型环带谐振器,具有结构紧凑,尺寸小,Q值高,非相邻耦合弱等优点.该谐振器在一侧设置了一个开口,改变开口位置,可以在较大范围内改变谐振器谐振频率,并且能够改变基频和二倍谐频之间的频率间隔.对于直连型馈线引入方式,H型环带谐振器容易实现外部Q值的匹配,同时对输入/输出端谐振器的谐振频率影响很小.本文还基于H型环带谐振器,采用2英寸双面YBCO高温超导薄膜设计并制作了用于CDMA移动通信系统的12节高温超导滤波器.该滤波器的中心频率为832MHz,相对带宽为1.6%.在70K温度下的测试结果显示滤波器的带内插入损耗低于0.28dB,反射损耗优于-15.5dB,带外抑制约为75dB,通带低频端带边陡峭度超过30dB/MHz,高频端带边陡峭度超过20dB/MHz.

AN HTS FILTER SUBSYSTEM FOR CDMA SYSTEM

In this paper, we presented a novel H-type resonator which has an open gap in its side. The resonator shows its character of the compact size, higher Q-factor, and weaker nonadjacent coupling. The resonance frequency can be easy changed by changing the position of the gap in a large scope to meet the requirement in different frequency band need, and easy to carry out for adjusting the space between main resonate frequency and second harmonic. The direct connection method was used for the feed line, it is convenient to match the external Q factor with sufficiently input/output of resonance frequency. A 12-pole HTS band-pass Filter with a 1.6% fractional bandwidth at 832 MHz was designed and fabricated using H-type resonator for CDMA mobile communication system. The measurement showed an excellent performance at 70K and agreements with the simulation prediction. The filter exhibits less than 0.28 dB insertion loss, 15.5 dB the return loss and a higher than 75 dB out-of-band rejection. Furthermore, the skirt slopes more than 20 dB/Mhz in the high frequency end was obtained.