This review is devoted to main research results of autodyne oscillators, which are stabilized by the additional high-Q cavity. We consider the practically interesting case of the strong reflected emission, when its amplitude is commensurable with the amplitude of the natural oscillations. In this case, at signal analysis in the stabilized oscillator, the account of not only non-linearity of the frequency function of resistive component of oscillating systems has the essential importance, but the reactive component non-linearity. The analysis of such a case is analyzable with difficulties by the analytical methods, and therefore it was performed with attraction of numerical methods on the base of developed mathematical model of the autodyne oscillator. We consider the point reflector model as the radar target. The autodyne equivalent circuit is presented by the parallel connection of the following conductivities: the operation cavity, the active element with negative conductivity, the stabilizing cavity with the coupling circuit and the load representing the impact of the reflected emission. As a result, we obtain the equation system describing signals’ formation in the both case of the weak and strong reflected emission. On the example of hybrid-integrated 8mm-range oscillator on the Gunn diode, the experimental research are preformed, which results qualitatively confirm the theoretical conclusions. As a result of the fulfilled researches of autodyne UHF oscillators, which are stabilized by the external high-Q cavity, we show the distinguished features of frequency, amplitude and phase characteristics under conditions of the high impact level of the proper reflected emission. The main results consist in the following. The main reason of anharmonic distortions of the autrodyne response in the case of the strong reflected emission is the anharnomicity of resistive and reactive components variation of the complex load conductivity as uniform variation of the reflected wave phase, as well as nonlinearity of frequency functions of resistive and reactive components of the oscillating system. Internal oscillator properties, such as its non-isochronity and non-isodromity, as well as a presence of frequency offset of the stabilizing cavity with respect to oscillating frequency, are the additional factors causing its distortions. However, the appropriate frequency correction of the stabilizing cavity allows compensation of oscillartor non-isochronity influence and thus to achieve of dynamic range widening of the autodyne system. For distortion level reduction of the autodyne response at the high level of reflected emission we can recommend the usage of the strong coupling between cavities, at that, one should tune the stabilizing cavity on minimum signal distortion. Under this condition, achievements of the single-circuit oscillator, which has the linear frequency functions of oscillating system conductivity, and the stabilizing oscillator, which provides the high frequency fixing capability, are simultaneously realized. Besides, when using of the autodyne sensor under conditions of the strong reflected emission, it is expedience to introduce additional damping, for instance, by means of the attenuator to reduce the distortion degree. It is stated that at strong reflected emission, the boundary value of the feedback parameter of the stabilized autodyne, at which the autodyne characteristics smoothness is lost, has the value less than 1. Reasons of such a deviation from the known condition for the case of weak emission are caused for features of the nonlinear behavior of the load reflection factor. Results of this review areconsidered as useful at interpretation of experimantal research od stabilized autodyne oscillators, which interacts with thre proper reflected emission, at analysis of autodyne signal formation, at calculations of characneristics, as well as at optimization of UHF oscillator parameters intended for the autodyne sensors etc.
Translated title of the contributionModern hybrid-integrated autodyne oscillators of microwave and mm-wave ranges and its applications. Part 13. Autodynes stabilized by an external cavity at strong reflected emission
Original languageRussian
Pages (from-to)5-27
Number of pages23
JournalУспехи современной радиоэлектроники
Volume74
Issue number1
DOIs
Publication statusPublished - 2020

    Level of Research Output

  • VAK List

    GRNTI

  • 47.00.00 ELECTRONICS. RADIO ENGINEERING

ID: 12460054