SU1483522A1 - Bandpass filter - Google Patents

Abstract

The invention relates to the field of radio engineering and can be used in microwave receiving paths operating under out-of-band interference conditions. The purpose of the invention is to increase the selectivity and dynamic range. This goal is achieved by introducing a pump signal shaping channel, including a directional coupler 6, narrowband amplifier 7, frequency converter 8, pump amplifier 9 and 10. Each reflecting element 2 or 3 includes a pump filter, a communication element, an antiphase power divider, attenuators, parametric diodes (PD), combinational frequency circuits (QCCH), signal circuits (SC), guiding filters, and matched loads. 3 il.

Description

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The invention relates to radio engineering and can be used in microwave receiving paths operating under out-of-band interference conditions.

The purpose of the invention is to increase the selectivity and dynamic range.

FIG. 1 is a block diagram filter; in fig. 2 is a block diagram of the reflecting element j in FIG. 3 shows a simplified construction of a reflecting element with a particular case of a directional filter.

The bandpass filter (Fig. 1) contains a double waveguide tee 1, reflective elements 2 and 3, matched loads 4 and 5, and a pump signal generating channel including 20 between circuits 18 and 19, a combination directional coupler 6, narrowband amplifier 7, frequency converter 8, amplifiers 9 and 10 pumping. Each reflecting element 2 or 3 (Fig. 2, 3) includes a pump filter 11, a communication element 12, an antiphase power divider 13, attenuators 14 and 15, parametric diodes 16 and 17, contours 18 and 19 combinational frequency, signal circuits 20 and 21, directional filters 22 and 23, matched loads 24 and 25.

Band-pass filter works as follows.

For a low input signal level, when its value is less than the set threshold value, the pump signal generation channel is open. In this case, the input signal enters the H-shoulder of the double waveguide tee 1, is divided equally between its side arms, is reflected at the resonant frequency from the reflecting elements 2 and 3, and taking into account the quarter-wavelength spacing, the reflected oscillations excite the E-shoulder of the double waveguide tee 1 and pass to the output of the band-pass filter. All vibrations that are not reflected by the reflective elements 2 and 3 are transferred to the agreed loads 4 and 5 and absorbed by them.

When the input signal exceeds the threshold value, the path of formation of the pump signal closes and the input signal through the directional coupler 6 is amplified by the narrowband amplifier 7, converted by

frequency in frequency converter 8 and, amplified in pump amplifiers 9 and 10, is converted into a pump signal.

Passing the filter 11 pump, attenuators 14 and 15, the pump signal affects the parametric diodes 16 and 17, while the process of passing the input signals in the reflective elements 2 and

3 is changing. The input signal is received (Fig. 2 and 3) on the antiphase divider 13 power and then through the directional filters 22 and 23 and the signal circuits 20 and 21 acts

on parametric diodes 16 and 17. As a result of direct conversion, in the circuits 18 and 19 of the combination frequency, antiphase oscillations of the combination frequency occur. Connection

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frequency through the element 12 connection leads to the fact that the amplitude of the resulting oscillations in them will in this case be minimal. In general, a change in the amplitude of oscillations in the combinational frequency circuits is equivalent to a change in the pump signal level and leads to a change in the transmission coefficient of the parametric device consisting of parametric diodes 16 and 17, contours 18 and 19 of the combinational frequency and signal circuits 20 and 21, and with increasing input signal the coefficient transmission decreases, which increases the dynamic range of the input signals of the bandpass filter.

When the input signal frequency changes, the phase shift between the signals acting on the inputs of the signal circuits 20 and 21 will be different from 180 °, which will lead to an increase in the amplitude of the resulting oscillations in circuits 18 and 19 of the combination frequency and a decrease in the transmission coefficient of the parametric device, and therefore , and an increase in the selectivity of the bandpass filter. In addition, the selectivity is increased due to the deterioration in this case of the phase conditions of the E-arm excitation of the double waveguide tee (the reflected signals are no longer rotivofaznymi).

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Claims (1)

Invention Formula Band-pass filter containing a double waveguide tee, H-shoulders which is the input, the E-arm is the output, and to the side shoulders with a quarter-wavelength spacing about the plane of symmetry of the double waveguide tee, reflective elements are made by the inputs, made identical and connected to the outputs with matched loads, characterized in that, in order to increase the selectivity and dynamic range, a pump formation channel was inserted, which includes a series-connected directional coupler, the auxiliary waveguide of which is connected to the H-arm of a double a watery tee, a narrowband amplifier, a frequency converter and two pump amplifiers, made identical and connected to the corresponding outputs of the frequency converter, and outputs to the control inputs of the reflecting elements, each reflecting element includes a pump filter, a communication element, an antiphase power divider and two channels made identical and each of which contains a series-connected attenuator connected by an input to the corresponding output of the pump filter, whose input is a control input of the reflecting element, a parametric diode connected to the combinational circuit, a signal circuit and a directional filter, while the combinational circuit of one channel is connected to the combinational frequency loop of the other channel through a communication element, the output of the directional filter is connected to the corresponding the side arm of the antiphase power divider, the main arm of which is the input of the reflecting element. one ig. 2 Pumping. one 25 Pumping Fig.Z at / 18 18 RU. 20