Dual mode cross-slotted filters realized with superconducting films

Abstract

A planar superconducting single stage dual mode filter has been investigated and tested. The basic element of the device is a square patch resonator diagonally crossed by unequal slots to provide both a size reduction and a simple way to couple the two degenerate modes. The effect of further cuts, realized on the conductor surface, is also investigated with respect to the power handling capability and miniaturization requirements. Two different filter topologies operating in C band with 1% fractional bandwidth have been designed and fabricated using Nb and YBa2Cu3O7 films grown on 10×10×0.5 mm3 LaAlO3 (100) substrates. Device response is studied performing power and intermodulation measurements. Third order products start to appear above the noise floor (−120 dBm) at input power Pin≈−20 dBm, whereas thermomagnetic breakdown is observed above 20 dBm.

Superconducting dual‐mode dual‐stage cross‐slotted filters

“…In this last configuration the filter shows a clearly enhanced selectivity with better global expected performances. The possibility of realizing quasi-elliptical and Chebyshev configurations has been verified also for filters with the patches directly connected through a 50°microstrip line of an appropriate length D. In this case only cross slots on the surface conductors (cross-type configuration [5]) are presented, proving that the presence of transmission zeros is mainly related to the cross slots, which introduce a phase shift between the modes [3]. In particular a 10% fractional bandwidth filter has been simulated by considering ⌬L ϭ 940 m and D ϭ 5.2 mm.…”

“…The simulated Chebyshev response, reported in Figure 3 (solid curve), was obtained by considering ⌬L ϭ 90 m, D ϭ 9 mm, Q Ext ϭ 100, and H ϭ 50 m, and all the other parameters unchanged in respect to the single-stage filter [5]. Because a relatively large distance is present between the two patches, the couplings K13, K24, and K14, are negligible.…”

“…A complete dispersion compensation scheme in systems using fiber Raman amplifiers have been discussed, where complete dispersion compensation indicates that the cumulated dispersion is compensated to zero [4]. It has also been investigated that for bit rates of 40 Gb/s or higher, the optimal dispersion compensation ratio (DCR) may be in the range of 80 -90%, rather than 100% [5]. This Letter analyzes the interactive effect of dispersion and nonlinearity with launched signal power, transmission length, and amplified noise taken into consideration.…”

“…According to these principles, C-band single-stage filters, with different values of the bandwidth, have been previously designed and realized with the use of high-quality 360-nm-thick YBCO film grown by a coevaporation technique and Tl 2 Ba 2 Ca 1 Cu 2 O 8 (Tl-2212) 1000-nm-thick films grown by MOCVD technique [5,7]. The single-stage YBCO filters have been characterized in terms of power handling, showing for a 10% bandwidth device a power handling at T ϭ 77 K higher than 33 dBm(2 W), limited by power supply.…”

Miniaturized dual-mode bandpass filter using inductively loaded cross-slotted patch resonator

“…In [8], a cross-slotted patch resonator is successfully developed to demonstrate the simultaneous size and loss reduction, and further to build up a novel dual-mode bandpass patch filter by suitably selecting the unequal cross-slot lengths along the two orthogonally diagonal planes. Since its proposal, this dual-mode filter has been gaining an increasing application in the exploration of superconducting filter blocks due to its advantageously high power handling capacity [9], [10].…”