Yu. V. Prokopenko

Frequency-tunable microwave dielectric resonator

A new type of tunable composite dielectric resonator (DR) has been designed, In the structure of this DR, a controllable insert was used to change the resonance frequency (f/sub 0/) in a wide spectral range, while preserving a high quality factor. The simplest of proposed resonance systems for obtaining f/sub 0/ control is a microwave DR crossed by an air slot, which is controlled by fast piezoelectric actuator. Analytical and experimental techniques were employed for optimization of the composite DR structure. It has been observed that this device can create a change up to 20%-25% in its resonance frequency.

Tunable dielectric resonator: Design and parameters

Dependences of normalized resonance wave-number versus normalized distance between parts of cube, sphere, disk, ring dielectric resonators (DR) and metal-dielectric resonator (MDR) are presented. Influence of resonators geometry and permittivity on resonant frequency alteration is discussed.

Microwave dielectric resonator frequency control

Constituent dielectric resonators and dielectric-metal mirror resonant structures capable of electrically controlling frequency with a preservation of high Q-factor were studied. Resonant frequency control could be realized by means of one structural component small mechanical shift using electrostrictive actuator. Examined dielectric resonant devices allow to change their resonant frequency up to 10-30%.

TEM cell electromagnetic field simulation

The main advantage of the developed software is the possibility to solve the electromagnetic field problem in the case of complicated shapes of shield and septums of TEM cell. It allows design of new and existing TEM cells and improves the uniformity of electromagnetic field and increases operating frequency range (by increasing cutoff, frequency of higher order modes and suppression of unwanted resonance). The software also allows one to investigate the influence of additional elements in the TEM cell design (for example, a lateral waveguide) on parameters and characteristics of TEM cell.

Microwave Annealing of Integrated Ferroelectric Films

Ferroelectric thin films integrated with semiconductors are playing growing role as a key element of future computer memory. One of the film processing stage needs heating in order to obtain a good crystalline-structured ferroeleotric. The principle idea of proposed new method is to use significant distinction between a large microwave absorption of ferroelectrics and low absorption of semiconductors in order to apply microwave radiation energy in immediate region of film integrated with semiconductor in complex sandwich. During the annealing process the less heating of wafer the better, to prevent complicate semiconductor structures from becoming blurred. Metal-oxide electrode(which is interface between semiconductor and ferroelectric) and thin film itself are the main absorbers of microwave energy short pulses. Their power, rise time, duration and-duty can be much more carefully controlled by the modern microwave technique than any other heating processes. Moreover, the microwave-assisted processing of ferroelectric film offers unique possibility for non-electrode and non-contact measurements of film electric parameters simultaneously with the annealing or other processes.

Complex Effective Dielectric Permittivity of Micromechanically Tunable Microstrip Lines

It is considered an influence of physical-topological parameters of controlled microstrip lines where characteristics modification is achieved by signal electrode movement over the substrate on effective dielectric permittivity and electromagnetic energy loss in the line expressed in form of complex permittivity. There are stated the ways of increase of sensitivity of effective dielectric permittivity modification to signal electrode shift and loss decrease. There are determined ultimate characteristics of tuning and loss. There are represented calculations of transfer factor effective permittivity corresponding to experimental results. These results can be used for development of controlled resonant elements and phase shifters with application of electrically tunable micromovement devices, such as piezo- and electrostrictive actuators or microelectromechanic systems. Due to application of invariant relations of physical-topological parameters represented calculations are suitable for estimation of tuning factors and loss of devices with micromechanical control in a wide range of operating frequency with application of wide range of materials.

Microwave structures electromecanical reconfiguration for tunable devices elaboration

Various highly tunable low-loss microwave devices are elaborated by piezoelectrically induced mechanical changes in the microwave structures utilizing high Q dielectrics. In this connection, an effective dielectric constant, epsieff, of used composite structures is controlled by fast actuator that results in energy distribution within the devices. Typical device consist of dielectric and metallic parts with an air gap between them that provides the largest perturbation in the electromagnetic field. By mini-actuator, the size of the air gap is changed and, as a result, the epsieff can be tuned that is used for a device control. Highly tunable dielectric resonators as filters as well as wideband, low-loss phase shifters are realized experimentally

Piezo-tuned microwave filters based on dielectric resonators

The functional possibilities of microwave filters based on dielectric resonators (DR) are extended by the control of their central frequency (f/sub 0/) and attenuation-frequency characteristic (AFC). With this purpose, frequency tunable high Q-factor DRs were used. Commonly accepted designs of DR-filters are unsuitable for such a control owing to the distortion of the AFC during controlling. Hence a new design of DR-based fitters is proposed, in which frequency is controlled with the undistorted shape of AFC. Based on these concepts, simple bandpass and bandstop frequency tuned filters were realized.

Fast Tuned Microwave Resonant Structures Based on Dielectric Resonator Reflected in Metallic Mirror

Constituent structures of 1/2 or 1/4 parts of dielectric resonators (DRs) reflected in the metallic mirrors were studied The structures were studied by electrodynamics in order to optimize constituent devices. By the controlling of air slot between parts of DRs and mirrors (which were waveguide walls), it is possible to change a central frequency of the constituent structure or its attenuation-frequency characteristic. Experimentally examined resonant devices show a high quality factor and allow to fast change of their resonant frequency (up to 20-25%). Based on these concepts, bandpass and bandstop frequency tuned filters were realized. Electronic adjustment of studied devices is possible as well, if the air slot of constituent resonant structure is shunted by the PIN diode.

Thermomechanically induced pyroelectricity and its possible applications

Abstract The feasibility of pyroelectric response creation from piezoelectric crystals has been examined. Performance evaluation of pyroelectric detectors with working substances SiO2, Bi12SiO20, GaAs and other sphalerite crystals has been revealed.