A. Usikov Institute of Radio Physics and Electronics,
National Academy of Sciences of Ukraine
12, Academician Proskura Str., Kharkiv 61085, Ukraine
Detection and Measuring Methods in the Analysis of the Multipath Channel Characteristics
The paper considers the parameter detection-and-measuring problem for a multielement target against the backgrounds of the nongaussian noise. A multielement target can serve as a signal acquisition simulation in a multipath channel due to re-reflection from the underlying terrain (land, sea) or elevated inversion tropospheric layers. The correlated nongaussian noise is described by the Markovian process with the given densities of the transition probabilities and the unconditional density of distribution. This pattern is typical for the noise due to the reflection from water surface, vegetated areas, elevated inversion layers in the troposphere, when the radar resolution cell is smaller than the representative scale of the surface inhomogeneities, e.g. the sea wave length. An exploratory model is suggested for the interference effects in the propagation channel. The number of sources and their characteristics are determined on the basis of the Fisher criterion for the significance estimation of signal source number.
A. Usikov Institute of Radio Physics and Electronics,
National Academy of Sciences of Ukraine
12, Academician Proskura St., Kharkiv 61085, Ukraine
Slot Resonances in Axially Symmetric Radiators of Pulse-Modulated and Monochromatic TM0n-modes
The resonances of TEM-modes supported by narrow radial and coaxial circular waveguides are analyzed. By exciting such resonances it should be possible to effectively control the electrodynamic characteristics of classical axially-symmetric radiators.
A. Usikov Institute of Radio Physics and Electronics,
National Academy of Sciences of Ukraine
12, Academician Proskura Str., Kharkiv 61085, Ukraine
Radial Three-Layered Dielectric Resonator with Perfect Conducting End Walls
The equation for complex frequencies of a radial three-layered cylindrical dielectric resonator with perfect conducting end-walls has been obtained. The influence of the middle layer filled different substances on a frequency and quality-factor of the resonator has been studied. Spectral and energy characteristics of a whispering gallery made have been studied for different values of the middle layer thickness and its position along the radius. Different behavior patterns of a resonator eigen frequency is revealed, on filling a middle layer by liquid with both small and large losses.
Synthesis and Analysis of Reflective and Mixed Active Multifunctional Plane Layered Media
Modeling a Digital Frequency Detector in the Micro-Cap 7 Environment
Nonlinear Phase Radio-Range Station for Measuring Distance to Radio Emission Sources
A. Usikov Institute of Radio Physics and Electronics,
National Academy of Sciences of Ukraine
12, Academician Proskura Str., Kharkiv 61085, Ukraine
The Diode Slit L-Cathode Electron Gun
A detailed consideration is given to a diode electron optical system (EOS) which is designed to form ribbon-shaped high-current density electron flows (EF). A slit-type L-cathode has been used as an emitter in the EOS. This cathode is formed along the line of joining the lateral surface of two different-in-structure materials. The emission current is extrated and an electron flow is formed in the homogeneous electric field with the EOS being arranged in the magnetic field which is close to the homogeneous one. A cathode system has been designed and developed, and the results from the experimental studies into its characteristics over the interval of accelerating voltages U=0.2-2.5 kV are presented. Conclusions are made about the possibility of using the electron streams that are generated by the EOS in electromagnetic oscillators operating in the short-wave part of the mm-wavelength range.
A. Usikov Institute of Radio Physics and Electronics,
National Academy of Sciences of Ukraine
12, Academician Proskura Str., Kharkiv 61085, Ukraine
Experimental Research into Static Ripple of Sheet Beams in Short-Millimeter Vacuum Tubes
The ripple level of a sheet electron beam from a diode gun is treated considering the action of electric field transverse components existing in the cathode area in view of the cathode assembly design. Experimental studies an amplitude ripple of beam versus cathode-anode separation and magnetic field induction are discussed. On this basis, some practical recommends are developed for improving the electron beam structure in the drift space of the millimeter wave oscillators.
A. Usikov Institute of Radio Physics and Electronics,
National Academy of Sciences of Ukraine
12, Academician Proskura Str., Kharkiv 61085, Ukraine
Automated Submillimeter Laser Power Stabilizing
The automatic power stabilization of submillimeter HCN-laser (l = 0.337 mm) has been investigated. The designing and testing results of power stabilization system realized on the base of MSP430 microcontroller and step driver are presented. If we use this system, laser output stability amounts to 2 % in more than 2 hours, it is enough for most measurement purposes.