Meander Line Resonator Research Articles

A novel miniaturized microstrip bandpass filter using a meander‐line resonator

AbstractWe report a novel miniaturized microstrip bandpass filter with a meander‐line resonator which exhibits a much smaller size. A very compact prototype, having a size of about λg0/8×λg0/8 at a center frequency of 2.445 GHz, was designed and fabricated for a 2.4 GHz bluetooth application. The measurement results of the proposed filter are in good agreement with the simulation results. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 319–321, 2002.

Microwave properties of YBa 2Cu 3O 7− x resonator under optical and thermal perturbations

Optically and thermally induced changes in the resonant frequency have been investigated for superconducting meander line resonators fabricated with YBa 2 Cu 3 O 7− x thin films. The variation of resonant frequency and resonant peak width is monitored as a function of the optical pulse energy P incident in the superconducting films, and temperature T in the range of 20 K to 80 K. The pair breaking effects induced by these two perturbations are well described by a squared dependence of the change in the resonant frequency, Δf(x) ∼ ( x x c ) 2 in the range of x x c = 0.26 to 0.72 where x = P , T . The results suggest that the optical response of the superconductor is bolometric.

High temperature superconducting microstrip line resonators for measuring surface resistance

Microstrip line resonators with transmission-line structures have been investigated to characterize microwave properties of rf sputtered YBa 2 Cu 3 O 7 − δ thin film deposited on LaAlO 3 substrates. Microstrip line resonators were designed to have fundamental resonant frequencies at 0.45 GHz and 7 GHz for meander line and straight line type resonators, respectively. With these resonators, the surface resistance of high T c superconducting films was measured and discussed as a function of temperature, input power and frequency. The low surface resistances of about 300 μΩ and 700 μΩ were observed at 0.458 GHz and 7.015 GHz, respectively. Experimental results of high T c superconducting resonators show pronounced improvement in unloaded quality factors Q u , compared to those of gold resonators. The resonant frequency shift with temperature was also verified.

Microwave compatible YBa2Cu3O7−δ films on (001)MgF2 substrates

High quality YBa2Cu3O7−δ (YBCO) films have been epitaxially grown on low dielectric constant, low loss tangent (001)MgF2 substrates using a double buffer layer scheme. The YBCO films are (001) oriented, exhibit Tc’s of 88–89 K with transition widths ≤0.5 K and Jc’s of 4×106 A/cm2 at 77 K in zero field. Dielectric resonator experiments indicate unloaded Q values in excess of 30 000 at 77 K and 24 GHz in the unpatterned films. Films patterned into meanderline resonators and operating at 10 GHz, 79 K, exhibit surface resistance (Rs)<1 m Ω suggesting near-future realization of low loss superconducting components in the millimeter-wave region.

Measurement of the surface resistance Rs of structured Y-Ba-Cu-O films on different substrates in the lower gigahertz range

A method for measuring the average surface resistance Rs of high-Tc superconducting thin-film strips on different substrates in the lower gigahertz range is presented. The method is based on quality factor measurements of a half-wavelength meanderline resonator in inverted microstrip form. The quality factor depends on the Rs of the conductor and the loss factor tan delta of the substrate. The evaluation takes into account the coupling between the neighbouring lines of the meanderline structure. Special geometrical dimensions allow the measurement of the quality factor between 15 K and the critical temperature. The surface resistance of the conducting material can be determined from the relation for the quality factor using a numerical program. Measurements were carried out between 0.5 and 4.0 GHz with Y1Ba2Cu3O7 films on Al2O3, YSZ, MgO and LaAlO3. Best Rs values were obtained on LaAlO3 around 0.5 m Omega at 77 K and 0.760 GHz.

YBCO thin films on Yttria stabilized Zirconia and LaAlO 3-growth and properties

Abstract Laser deposition was used to deposit YBaCuO thin films on Yttria-stabilized Zirconia substrates, at substrate holder temperatures of 710–765 °C. We observed a transition from singlecrystalline to polycrystalline growth at a temperature of ∼750 °C. All films were highly c-axis oriented and had critical temperatures between 89.5 and 92 K. In the twinned singlecrystalline films, the lowest measured microwave surface resistance was 0.37 mΩ at 4.2 K and 21.5 GHz, and the highest critical current 5×10 6 A/cm 2 at 77 K. The polycrystalline films had up to a factor of 50 higher surface resistance and a factor of 10 lower critical current. A meander line resonator made of a film on a LaAlO 3 substrate, showed a microwave surface resistance of 5μΩ at 4.2 K and 2.5 GHz.

Microstrip resonators using two-sided metalorganic chemical vapor deposited Er-Ba-Cu-O thin films

We have measured very low microwave losses in microstrip resonators produced in a newly developed process which deposits high-temperature Er-Ba-Cu-O superconducting films by metalorganic chemical vapor deposition on both sides of a LaAlO3 substrate. These in situ films have critical temperatures of 92 K. High Tc superconductor (HTS) linear microstrip resonators demonstrated Q’s of 3500 at 10 GHz and 4.2 K, corresponding to surface resistances less than 330 μΩ, which is 45 times better than measured silver resoantors. HTS meanderline resonators with a fundamental frequency of 1.3 GHz have Q’s of 9600 at 4.2 K. Identical silver meanderline circuits have 300 times more surface resistance than HTS circuits.