Tamio Kawaguchi

Miniaturized High-Temperature Superconductor Bandpass Filters Using Microstrip S-Type Spiral Resonators

At frequencies currently used by mobile communications, many of the microstrip half-wavelength resonators are too large to realize miniaturized filters. For this reason, very small-sized microstrip spiral resonators and filters, using high-temperature superconductors (HTS), have been studied recently. In this paper, the resonant and coupling characteristics of microstrip G-type and S-type spiral resonators are investigated first by using an electromagnetic simulator. Then small-sized 4-pole, 8-pole. and 16-pole Chebyshev bandpass filters using S-type spirals are designed, respectively, with a midband frequency f 0 = 1.93 GHz. The frequency responses of the filters satisfy well the desired specifications, and the measured frequency response of the 8-pole HTS filter agrees well with the theoretical prediction.

A Miniaturized High Temperature Superconducting Bandpass Filter Using CPW Quarter-Wavelength Spiral Resonators

A novel compact high temperature superconducting BPF is developed by using coplanar waveguide quarter-wavelength spiral resonators. The filter is a 5-pole Chebyshev BPF with a midband frequency of 5.0GHz and an equal-ripple fractional bandwidth of 3.2%. The CPW spiral resonator is made as small as 1.02times2.1mm2. As a result, the 5-pole filter occupies an area of only 7.65x2.11mm2, less than one-third that of a newly reported CPW interdigital filter. The filter is fabricated by using 0.5mum YBCO film deposited on an MgO substrate. No bond-wire air-bridges are used and no post-tuning is made in the experiment. The measured filtering characteristics agree well with EM simulations and show low passband insertion losses in spite of the small size of the filter

A novel compact high temperature superconducting CPW bandpass filter

A novel high temperature superconducting interdigital bandpass filter is proposed by using coplanar waveguide quarter-wavelength resonators. The CPW resonators are arranged in parallel, and consequently the filter becomes very compact. The filter is a 5-pole Chebyshev BPF with a midband frequency of 5.0GHz and an equal-ripple fractional bandwidth of 3.2%. It is fabricated using a YBCO film deposited on an MgO substrate. The measured filtering characteristics agree well with EM simulations and show a low insertion loss in spite of the small size of the filter.

A Novel Compact HTS Interdigital Bandpass Filter Using CPW Quarter-Wavelength Resonators

A novel high temperature superconducting interdigital bandpass filter is proposed by using coplanar waveguide quarter-wavelength resonators. The CPW resonators are arranged in parallel, and consequently the filter becomes very compact. The filter is a 5-pole Chebyshev BPF with a midband frequency of 5.0 GHz and an equal-ripple fractional bandwidth of 3.2%. It is fabricated using a YBCO film deposited on an MgO substrate. The measured filtering characteristics agree well with EM simulations and show a low insertion loss in spite of the small size of the filter.