A 5 GHz high-temperature superconducting reaction-type transmitting filter based upon split open-ring resonators

作者：Futatsumori S^*; Hikage T; Nojima T; Akasegawa A; Nakanishi T; Yamanaka K

来源：Superconductor Science and Technology, 2008, 21(4): 045014.

DOI：10.1088/0953-2048/21/4/045014

A new kind of high- temperature superconducting ( HTS) transmitting filter based on a reaction- type resonator is presented. The purpose of an HTS reaction- type filter ( HTS- RTF) is to eliminate the intermodulation distortion noise generated by microwave power amplifiers such as those employed in mobile base stations. An HTS- RTF enables both higher power handling capability and sharper cutoff characteristics compared to existing planar- type HTS transmitting filters, since a reaction- type resonator does not resonate with high power fundamental signals. To achieve steep skirt characteristics and high power handling capability simultaneously, a 5 GHz three- pole HTS- RTF using a split open- ring resonator is designed. This split open- ring resonator offers low maximum current densities and a high- unloaded Q factor with low radiation. The designed prototype filter has Chebyshev characteristics with a centre frequency of 4.95 GHz and a bandwidth of 1.5 MHz. The HTS- RTF is fabricated using a double- sided YBa(2)C(3)O(7-delta) thin film deposited on a 0.5 mm thick MgO substrate. The measured filter shows an insertion loss of less than 0.1 dB and a third intermodulation distortion value of - 56.7 dBc for a 40 dBm passband signal. In addition, adjacent channel leakage power ratio ( ACLR) measurements using an actual wideband CDMA signal confirm an ACLR improvement of about 10 dB for a four- carrier signal with power up to 40 dBm.

• 出版日期2008-4