SU572700A1 - Frequency-selective limiter on nuclear resonance principle - Google Patents

Description

one

The invention relates to radio spectroscopy and is intended to selectively selectively selectively limit interference with a known frequency spectrum and can be used in various radio engineering devices in which the signal is extracted at the level of interference.

The known frequency selective limiter, based on turf magnetic resonance and including resonators and a working substance, has a narrow frequency band.

The closest technical solution to the present invention is a frequency-selective limiter on nuclear magnetic resonance, made in the form of a bridge circuit with input and output transmission lines and with included in the shoulders of the bridge through inductive loops resonators with the working substance.

The selectivity of such a limiter is determined by the width of the nuclear magnetic resonance absorption line, and the passband is determined by the inhomogeneity of the constant magnetic field. The balance condition of the bridge in this limiter is influenced not only by the absorption signal of the working substance, but also by its dispersion signal, which disrupts phase balancing bridge, which also reduces the working frequency band.

The disadvantage of this limiter is a relatively narrow operating frequency band, which determines the difficulty of creating a highly inhomogeneous constant magnetic field, which would also provide compensation in a wide frequency band of the dispersion signal. Such a limiter circuit is not suitable when using ferromagnets as a working substance, because in ferromagnets there is no possibility of compensating for the dispersion signal by the method described, since control of the internal multiple magnetic fields of the substance is not possible. At the same time, the use of a ferromagnet as a working substance is particularly promising from the point of view of reducing the size of the limiter by eliminating permanent magnets, as well as from the point of view of possible increase in the working medium.

frequency bands.

The aim of the invention is to increase the frequency band and reduce the size of the limiter; This is achieved in that in the proposed

the limiter, the working substance, for example, a paramagnetic or ferromagnetic, is placed in both resonators, and the switching on of the resonators is antisymmetric. Inductive loops are made in different sizes. AT

The shoulders of the bridge circuit include attenuators, and in one shoulder they reach the resonator, and in the other after the resonator.

FIG. 1 and 2 show possible block diagrams for implementing the proposed limiter at high frequencies; in fig. 3 - the principle of action of the limiter.

FIG. 1 and 2 the following notation is accepted: 1 and 2 are resonant systems with a working substance, 3 and 4 are input and output tees, 5 and 6 are output and input communication elements (inductive connection loops): 7 is an attenuator, i / in, t / o - input and output signals, respectively.

A different power level in resonant systems is achieved in the circuit depicted in FIG. 1, due to the different sizes of the communication loops at the input and output of the resonant systems in the various arms of the bridge, and in the circuit shown in FIG. 2, due to the inclusion of attenuators in one arm to the resonator, in the other - after the resonator. Anti-phase removal of signals from resonators 1 and 2 is achieved by reciprocating the input coupling loops in the resonators of the various arms by 180 °. If paramagnets are used as the working substance, both resonators are placed in a constant magnetic field; when using a ferromagnet, a constant magnetic field is not needed.

FIG. 3 is indicated: Search is the input signal level corresponding to the saturation of the working substance in the resonant system with a high power level (resonator 1, fig. I, 2); Ll is the input signal level corresponding to the saturation of the working substance in a resonant system with a low power level (resonator 2, figs. 1, 2).

When a weak signal limiter is applied to the input (signal I), the working substance in resonator 1 is in saturation, and in resonator 2 it is not in saturation, as a result

there is an imbalance. - the bridge and at the output of the limiter the signal is proportional to the input. The dispersion signal does not disturb the phase balancing of the bridge, since, due to its independence from the power level, it is the same for both arms of the bridge. Thus, the dispersion signal is automatically compensated. When applied to the input limiter strong signals (signals And and III), the working depth

in both resonators on the go in saturation,

the bridge will be balanced and the signal will not exit

will not be. Dispersion signal and in this case

automatically compensated.

The invention allows to obtain automatic compensation of the dispersion signal, using not only paramagnetics, but also ferromagnets as a working substance, which leads to an increase in the working frequency band.

Claims (3)

Invention Formula A frequency selective limiter on sod magnetic resonance, made in the form of a bridge circuit with input and output transmission lines and with included in the shoulders of the bridge through inductive loops resonators with a working substance, characterized in that, in order to increase the working cavity of the frequency and size reduction of the limiter, the working substance, such as a paramagnetic or ferromagnetic, is placed in both resonators, and the inclusion of the resonators is made antisymmetric. 2. The limiter according to claim 1, characterized in that the inductive loops are made of different sizes. 3. The limiter according to claim 1, characterized in that the shoulders of the bridge circuit are included attenuator, and in one shoulder - to the resonator, and in the other - after the resonator. L L Out J (/, ig sh