THE INFLUENCE OF ACCOMPANYING AM ON THE FORMATION OF SIGNALS FROM AUTODYNE SHORT-RANGE SENSORS WITH FM

摘要

This paper presents the results of studies on the peculiarities of signal formation from autodyne short-range radar systems with combined amplitude-frequency modulation. Expressions are obtained for calculating the autodyne signals of a single-loop oscillator with an arbitrary law of simultaneous amplitude and frequency modulation in the general case of an arbitrary ratio of the reflected radiation's delay time and the period of the modulating function. Calculations for the characteristics of amplitude selection and their cross sections, as well as the time and spectral diagrams of autodyne signals for the modulation of the amplitude and frequency according to a harmonic modulation law, have been conducted. This paper considers cases when the delay time of the reflected radiation is much briefer than the duration of the modulation period, as well as when their values are comparable. Experimental studies were carried out using a Ka-band Gunn diode oscillator. Variants of electrical frequency control using a varicap and a Gunn diode's bias circuit are investigated. The obtained results made it possible to formulate the requirements for the parameters and characteristics of hybrid-integrated circuits and frequency modulation modules while also outlining ways to further improve them.