Anatoli Deleniv

Narrowband Y-Ba-Cu-O filter with quasi-elliptic characteristic

The compact meander-shape configuration of planar resonators is suggested for applications in narrowband filters with quasi-elliptic characteristic. The quasi-elliptic frequency response with two transmission zeroes at the edges of the passband is provided by the specific symmetry of the coupled resonators and is controlled by an appropriate choice of the resonator dimensions and the couplings between the resonators. The 12-pole quasi-elliptic filter with 0.5% fractional bandwidth at 1.775 GHz has been designed using meander-line microstrip resonators and manufactured on a double-sided YBCO film on a LaAlO/sub 3/ substrate. The filter exhibited the in-band insertion loss less than 0.5 dB at T=60 K, the return loss of 20 dB, the out-of-band rejection better than 75 dB, and 40 dB/MHz slope of the characteristic.

Tunable ferroelectric filter-phase shifter

Design of a tuneable filter-phase shifter is presented. Thin ferroelectric film varactors are used to provide voltage tuneable phase shift in a silicon coplanar waveguide (CPW). Varactors with zero bias capacitance 0.17pF, loss tangent tan/spl delta/-0.04 and 20% tuneability provide continuous voltage tuneable phase shift up to 90/spl deg//spl plusmn/5/spl deg/ at 19 GHz with 10% bandwidth. The figure of merit is about 30/spl deg//dB. The sizes of the phase shifter silicon chip are less than 2/spl times/5.5mm. The phase shifter is designed for possible integration in silicon MMICs.

Development of CAD tool for a design of microwave planar HTS filters

Accurate design of microwave planar high-temperature superconducting (HTS) filters is obtained using a computer-aided design tool, which provides simulation of characteristics of the multicoupled transmission-line structures. The quasi-static spectral-domain method is applied. In order to achieve a good correspondence between measured and simulated filter performance, correct models of the microwave propagation characteristics of HTS planar transmission lines have to be used in the simulation procedure. The goal of this paper is to demonstrate that it is possible to design the planar HTS filters that do not need additional trimming after manufacturing. The trimmingless filters can be used in mass production for the next generation of mobile communication systems.

Millimetre-Wave Phase Shifter Based on Dielectric Rod Waveguide

In this work we propose a novel millimetre-wave phase shifter targeted on thin ferroelectric film technology. Architecture of the phase shifter is proposed to use a dielectric rod waveguide with a periodic printed array of electrically small dipoles loaded with a ferroelectric varactor (pin diode, Schottky diode, etc.) with the function of control the phase of the propagating wave. The proposed architecture of the phase shifter is verified by measuring two prototypes, where the tuneable elements (ferroelectric varactor) are replaced by non-tuneable capacitors with 10 fF and 15 fF respectively. The measurements revealed a considerable phase shift and small insertion losses. It is demonstrated that the proposed periodic structure using the dielectric rod waveguide allows to fully realize a potential of known tuneable elements at millimetre-wavelengths.

LTCC compatible ferroelectric phase shifters

Two phase shifters with novel topologies are presented. The phase shifters are based on LTCC compatible ferroelectric films with /spl epsiv//sub r/=200, and tan/spl delta/=0.04 at 10 GHz. A Ku-band phase shifter is designed to provide DC bias independent matching in the wide frequency range. It has microstrip design where ferroelectric film is used as a substrate and requires relatively low DC bias voltages. The phase shifter showed -15dB matching in /spl sim/50% bandwidth and 15/spl deg//dB figure of merit. In X-band phase shifter, the ferroelectric film is deposited on the low permittivity substrate. Using such two layered substrate a loaded line phase shifter based on coplanar-plate varactors is realized. The varactors are included in the circuit ground and are connected with the microstrip using vias. This designed allows reduction of overall loss due to more efficient use of ferroelectric. The figure of merit of this phase shifter is 207dB at 10 GHz.

Orientation and direct current field dependent dielectric properties of bulk single crystal SrTiO3 at microwave frequencies

The dielectric properties of bulk single crystal SrTiO3 (STO) are studied in the temperature range 30–300 K, under dc field 0–10 kV/cm at 1.0 kHz and in the frequency range 0.3–2.0 GHz. Two sets of circular disk shaped parallel plate resonators have been fabricated and tested experimentally. In the first set thin YBa2Cu3O7 films have been epitaxially grown on both surfaces of [100] STO disks. In the second set, three crystal orientations of SrTiO3 [100], [110], and [111] have been used to make parallel-plate resonators with evaporated Cu/Ti electrodes. No peculiarities in field dependent dielectric permittivity are detected for STO with smaller densities of impurities. For samples with larger impurity densities double loop hysteresis is observed in the dc field dependent permittivity. For all orientations the losses are minimum at temperatures about 50–55 K. The losses at microwave frequencies increase with the applied dc field regardless of the orientation of the STO crystal. At relatively high dc fields...

High-temperature superconductor filters: modeling and experimental investigations

10-pole HTS microstrip band-pass filters with central frequency 1.75 GHz have been designed, manufactured, and investigated without any trimming in the linear and nonlinear regimes. A high filter performance with insertion loss not more than 0.5 dB and power handling capability up to 10 W of input power at T=60 K has been observed. Different commercial and home-made software were used to simulate the filter characteristics.

Open resonator technique for measuring multilayered dielectric plates

A generalized formulation of an open resonator technique including multilayer dielectric plates is proposed. It is used for experimental characterization of the permittivity and loss tangent of one of the layers. An experimental measurement system is developed and used to measure the dielectric properties of high-permittivity ferroelectric films, which demonstrates the utility of the approach. The loss tangent of the layer studied is obtained with the analytical formula derived, which speeds the data processing procedure. It is experimentally shown that the air gap between the sample and the plate mirror may significantly reduce the accuracy of the open resonator technique. It is also shown that the formulation developed here provides the means to deal with the problems associated with the air gap.

Two-pole tunable bandpass filter based on YBCO plated single crystal KTO disk resonators

This paper addresses design and experimental characterization of a two-pole 1.5% bandpass tunable filter operating at 0.9 GHz and 77 K. The filter is based on two YBCO plated KTaO/sub 3/ disc resonators (0.5-mm-thick, 10 mm in diameter) and utilizes the TM/sub 020/ mode. The tunability is achieved through the nonlinear DC electric field dependence of the relative dielectric constant of KTaO/sub 3/. About 5% tuning range is achieved at 500 V driving voltage. Although the insertion losses are relatively high (about -5 dB at 500 V) the shape of the passband is essentially stable. A rather good agreement between simulated and experimental performances is found.

Design of an interdigital hairpin bandpass filter utilizing a model of coupled slots

A design methodology of an interdigital hairpin filter based on a full-wave model of coupled slots is developed and discussed. It is applied to design a five-pole bandpass filter centered at 1.7 GHz; with 1.75% relative bandwidth. A low level of in-band insertion loss is achieved using high-temperature superconductor electrodes. Experimental data are presented and compared with the simulated response. A model of coupled slots embedded in a layered lossy media is developed on the basis of the spectral-domain approach. The multiport admittance (impedance) matrix of the coupled slots is formulated using the E-H duality principle. It is successfully applied in the design of the filter.