G. P. Ermak

Phase Locking of 2-mm Wave Sources Upon High-Order IMPATT Multipliers

We describe experiments resulting in the phase locking of two electrically tunable 2-mm wave sources based on active high-order IMPATT multipliers. Phase locking modes were tested on a pair of identical multiplying sources (master and slave) with the tuning ranges 138.5+/−1.5 GHz (master) and 140.0+/− GHz (slave). The phase lock loop (PLL) system is used to lock the slave source to the master source. The multipliers of this type can translate the spectra of highly stable centimeter-wave oscillators to any part of the millimeter range with the output power 100÷20 mW over the 30 to 140 GHz range without additional amplification. The phase locked sources operate over a 3% frequency band with low phase noise and rapid frequency tuning. The amplitude-frequency characteristics of the sources are presented with the locking-mode signal spectra.

Particularities of double-diode autodyne characteristics

Calculations of main characteristics of a two-diode autodyne subject to the influence of eigen reflected radiation are performed. It is used, at that, a mathematical model in the form of two mutually synchronized partial oscillators with a delayed mutual coupling between them. Particularities of behavior of amplitude and phase characteristic variations of partial oscillators, frequency and phase difference, along with the response of active elements in the power supply circuit are considered.

Mathematical model of double-diode autodyne

A mathematical model has been developed for a double-diode autodyne oscillator affected by the proper reradiation. The model represents two mutually-synchronized partial oscillators with time delayed coupling between them. It is possible for studying peculiarities of autodyne amplitude variations of the partial oscillators, autodyne variations of frequency and phase difference and, also, in the power supply circuit responses of the active elements.

Modernization and calibration of intrferometer of TOKAMAK “Compass”

This article presents “Compass” TOKAMAK microwave diagnostics calibration and results accuracy enhancing experiment methodology. Main subject is microwave diagnostic system phase measurements description. Additional interest is mistakes, attendant to phase measurement. Emphasis is put on phase detectors measurements mistakes correction methodology; two different phase meter configurations are described. Phase detectors, based on AD8302 CPLD, results processing methodology are presented.

Two-wavelength millimeter wave “unambiguous” heterodyne interferometer

The paper presents the results of upgrading and description a two-wavelength “unambiguous” microwave interferometer for line integrated electron density measurements at the “COMPASS” tokamak. The probing signals in the frequency range of 131 and 133 GHz are generated by IMPATT diode oscillators. Double conversion heterodyne receivers are used for detection. Use of each oscillator is twofold: as a source for the probing signals and as a local oscillator for heterodyne detection. The plasma is probed with two separate waves of different wavelengths traveling along identical paths to meet each other. Each probing beam experiences a different phase shift φ₁ and φ₂ and the “unambiguous” interferometer determines the difference φ₁-φ₂. The phase measurement is realized by using the 3 pieces of phase detectors based on pairs of phase/gain evaluation boards (AD8302). Application of the phase detectors provides information on the average plasma concentration in real time and restore the values of plasma density in the case of phase jumps by an amount > 2π.

Radar sensors for hump yard and rail crossing applications

A radar sensor as part of the automatic shunting system has been developed for the remote control of track occupancy in the hump yard and railroad switch territories, enhanced by the speed control of rolling stock when it passes by the retarder. The sensors are equipped with systems of remote control. They are provided with systems of internal parameter diagnostics and transmission of the radar and service information to the control point and can work in information networks.

Autodyne sensors for hump yard and rail crossing applications

The Ka-band radar autodyne sensors are suggested for railway applications, including the check and remote control of the track occupancy/vacancy and the car speed at hump yards and as part of an obstacle detection unit for monitoring the rail tracks and the block unit lids on guarded and non-guarded rail crossings in an effort to reduce the risk of accident on railroads.

Autodyne effect application for stability analysis of the steady-state mode of UHF oscillating systems

The autodyne characteristics are oifered to use for steady-state stability analysis of the UHF oscillators. Theoretical substantiation of the proposed method is performed on an example of the oscillating systems mathematical model presented in the form of two mutually-locked partial oscillators under a condition of strong coupling between them. Peculiarities of stable functioning zones for oscillating systems are described at different partial oscillator parameters and for various conditions of their mutual coupling. Experimental investigations are performed based on the 8mm-wavelength range double-diode oscillator.

Influence of the autodyne oscillator coupling degree with antenna upon its transfer and noise characteristics

Analysis results of coupling degree influence of the autodyne oscillator with an antenna are presented together with influence of the impedance characteristic type (soft or rigid) of the active element on the coefficients of autodyne amplification, autodyne frequency deviation and power transfer as well as on the noise parameters and characteristics. Analytical and numerical calculations of above-mentioned parameters and characteristics are performed, and results of experimental investigations of the 8mm-range Gunn diode autodyne are given.

Signal analysis of a double-diode autodyne

Analysis results of autodyne signals of the double-diode oscillator, which is under influence of the proper reflected emission from the moving object, are presented. The analysis is performed on the base of the autodyne mathematical model presented in the form of a system of two mutually-locked partial oscillators under condition of strong mutual coupling. Peculiarities of signal formation are considered for various parameters of partial oscillators and coupling conditions. Experimental data are obtained for the 8mm-range Gunn double-diode oscillator of the flange type.