RU2773775C1 - Binary phase modulator of the sub-thz frequency range - Google Patents

Abstract

FIELD: radio engineering.

SUBSTANCE: invention relates to the field of radio engineering. This effect is achieved by the fact that the phase modulator contains a power divider, to which a carrier signal with a frequency of 100-900 GHz is applied, the first output of the power divider is connected to the first input of the first amplitude modulator, and the second output of the divider is connected in series with a passive delay line and the first input of the second amplitude modulator, wherein the output of the first modulator is connected to the first input of the quasi-optical bridge, the output of the second modulator is connected to the second input of the bridge. The phase-modulated signal is obtained at the first output of the quasi-optical bridge, while passing from the second input of the quasi-optical bridge to its first output, the intermediate signal receives an additional phase shift of 90°.

EFFECT: providing the possibility of obtaining a binary phase-shift keyed signal with a low level of phase noise and a high transmission rate.

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Description

The invention relates to radio engineering, namely to communication systems, and can be used for data transmission in the sub-THz frequency range.

One of the key components of a data link is a modulator that encodes digital information by changing the characteristics of the carrier signal. For telecommunications use, phase modulation is preferred. Changing the phase of the signal is the most difficult task, which means that there will be less phase interference from the environment - and fewer errors in the transmission of information. This approach makes it possible to approach the theoretical limit of the transmission rate in the development of appropriate devices.

Until recently, the sub-THz frequency range has been little mastered, and although a large number of techniques and laboratory specimens have been developed that allow modulation in this range, there are no practically applicable phase manipulators for this range.

An important parameter is at what frequency the modulation is actually performed. Direct modulation includes techniques and devices that modulate at the sub-THz frequencies themselves. Indirect cases include those cases when modulation is performed at frequencies higher or lower, followed by conversion to the sub-THz frequency range. The development of indirect modulation devices is due to the fact that in the optical (higher) and radio (lower) ranges, modulation methods and devices are better developed and have better characteristics in terms of stability, power, and noise. The sub-THz optical downsampling approach generally prevails, as this introduces less noise than upsampling.

From the prior art known technical solution described in the application US 20210328841, "Millimeter wave transmitter)), publ. 10/21/2021, IPC H04L 27/20, H03F 3/245. The proposed phase modulator QPSK operates in the range of 30-300 GHz. However, in the described device, amplifiers and frequency multipliers are used. These elements introduce a large amount of phase noise into the final phase modulated signal.

The closest in technical essence to the claimed device is a phase modulator described in US patent 9298024 "Semiconductor Mach-Zender modulator and method to drive the same", publ. 03/29/2016, IPC G02F 1/035; G02F 1/225. It contains a power divider in which the optical beam is split into two beams. Each arm has a modulation block, with a phase shift block located in one arm. The signals from both arms enter the adder, at the output of which a phase-modulated signal is obtained. In this case, both modulation blocks are fed with digital data from the same source, but before being fed to one of the modulation blocks, the digital data passes through a logic inverter. The proposed device operates in the optical wavelength range, so many elements of the modulator are made on the basis of optical fiber. The received phase-modulated signal is transmitted in the optical range. Accordingly, the main disadvantages of the device - the impossibility of signal transmission in free space in the presence of rain, snow, fog, smoke.

The problem to be solved by the proposed invention is to create a simple design of a phase modulator of the sub-THz frequency range, operating at a power level from 10 mW to 1 MW, which makes it possible to obtain a binary phase-shift keyed signal with a low level of phase noise and transmit it at a high speed.

The technical result in the developed device is achieved due to the fact that it contains a power divider to which a carrier signal is applied, the first output of the power divider is connected to the first input of the first modulation block, and the second output of the divider is connected in series with the phase shift block and the first input of the second modulation block . Moreover, the output of the first modulation block is connected to the first input of the adder, the output of the second modulation block is connected to the second input of the adder, and the phase-modulated signal is obtained at the output of the adder. In this case, digital data from the same source is supplied to the second inputs of both modulation blocks, but before being fed to one of the modulation blocks, the digital data passes through a logic inverter. New in the developed device is that the carrier signal is a microwave signal with a frequency of 100-900 GHz, each modulation block is an amplitude modulator with a waveguide input and output. The phase shift block is made in the form of a passive delay line providing a phase shift by 90°, the adder is made in the form of a quasi-optical bridge, and the phase-modulated signal is taken from the first output of the quasi-optical bridge. When passing from the second input of the quasi-optical bridge to its first output, the intermediate signal receives an additional phase shift by 90°, and the second output of the quasi-optical bridge is connected to an unwanted signal absorber, and all microwave signals between the blocks are transmitted using waveguides of the main section.

In a particular case of the implementation of the device being developed, it is advisable to use amplitude modulators of the resonator type as amplitude modulators.

The invention is illustrated by the following drawings.

In FIG. 1 shows a diagram of the developed device.

In FIG. 2 shows the principle of operation of a quasi-optical bridge.

In FIG. 3 schematically shows a resonator-type amplitude modulator.

The sub-THZ phase modulator shown in FIG. 1, contains a power divider 1, the carrier signal to which is supplied from the source 2 of the microwave signal, a passive delay line 3, the first amplitude modulator 4 and the second amplitude modulator 5, as well as a quasi-optical bridge 6. To the first output of the quasi-optical bridge 6, where a phase-shift keyed signal, an antenna 7 is connected, and an absorber 8 is connected to the second output of the quasi-optical bridge 6. The digital signal source 9 is connected to the second input of the first amplitude modulator 4 directly, and to the second input of the second amplitude modulator 5 through a logic inverter 10.

The operation of the proposed device is as follows.

The source 2 of the sub-THz frequency range emits a carrier signal, which is fed to the power divider 1, which ensures the coherence of the signals in each arm at the output of the power divider 1. In the first arm of the path, the signal from the first output of the power divider 1 is fed to the first input of the first amplitude modulator 4, and from the second output of the power divider 1, the signal is fed through the passive delay line 3 to the first input of the second amplitude modulator 5. Each amplitude modulator has the first input and output made in the form of waveguides, and the passive delay line 3 provides a signal phase shift by 90°. Digital data from the source of digital signals 9 is fed to the second input of the first amplitude modulator 4, at the same time, the data is inverted to the second input of the second amplitude modulator 5, as it passes through the logic inverter 10. Thus, in each of the arms, the carrier is modulated signal with a mutually opposite digital signal. Then the signals received at the outputs of the first and second amplitude modulators 4, 5 are summed in the quasi-optical bridge 6.

Due to amplitude modulation, in fact, at every moment of time, the signal is present only at one of the inputs of the quasi-optical bridge 6 (Fig. 2), while at the first output 1 of the quasi-optical bridge 6, a signal is received with a phase shift of 0° or +180°, depending on in which of the legs of the tract the signal is suppressed.

By applying a signal to the first input 11 of the quasi-optical bridge 6, at the first output 12 a signal with a phase shift of 0° is obtained, and at the second output 13 a signal with a phase shift of +90°. By applying the same signal to the second input 14 of the quasi-optical bridge 6, at the first output 12 a signal with a phase shift of +90° is obtained, and at the second output 13 a signal with a phase shift of +0°. In the developed device, the signal arriving at the second input 14 of the quasi-optical bridge 6 first passes through the passive delay line 3 of the carrier signal in the second arm. Thus, the signal arrives at the second input 14 of the quasi-optical bridge 6 with a phase shift of +90°, and in the quasi-optical bridge 6 itself, a phase shift of +90° is added. As a result, at the first output 12 of the quasi-optical bridge 6, a signal with a phase shift of +0° is received (Fig. 2a), when the signal arrives at the first input 11 of the quasi-optical bridge 6, or a signal is received with a phase shift of +180° (Fig. 2b), when the signal is fed to the second input 14 of the quasi-optical bridge 6.

Thus, by controlling the amplitude of the signals arriving at the first 11 and second 14 inputs of the quasi-optical bridge 6, it is possible to modulate the phase of the signal at the first output 12 of the quasi-optical bridge 6. The phase-modulated signal from the first output 12 of the quasi-optical bridge 6 can then be output to the antenna 7 and emitted into free space. The second output 13 of the quasi-optical bridge 6 receives an unwanted signal, which is sent to the absorber 8.

As amplitude modulators 4 and 5, in a particular case, amplitude modulators of the resonator type are used (Fig. 3). In FIG. 3 is a schematic representation of a resonator-type modulator, where the initial microwave signal is supplied to the waveguide input 15, an amplitude-modulated signal is output from the waveguide output 16, and digital data is supplied to the second input 17 in the form of a control laser pulse, a semiconductor plate 18 is placed in the resonator chamber This design of the modulator allows the signal to be modulated with high power, as well as to avoid unnecessary losses, signal re-reflections and excessive noise increase.

In a specific implementation of the proposed device as a source 2 of the microwave signal, the authors used a BWO with an output signal frequency of 200÷580 GHz and a power of 10 mWh ÷ 1 W. A directional waveguide coupler is used as a power divider 1, the passive delay line 3 is made in the form of an additional section of the waveguide of the calculated length. Quasi-optical bridge 6 (adder) has the following parameters: operating frequency 267 GHz, operating frequency band: not less than 800 MHz. A 20 W semiconductor laser operating at infrared wavelengths was used as a source of digital signals 9. The inverter 10 is implemented on standard logic circuits.

Thus, the developed phase modulator makes it possible to obtain a binary phase-modulated signal at the output in the frequency range of 100-900 GHz, with a power in the range from 10 mW to 1 MW, while the manipulation is carried out at the fundamental frequency without the use of intermediate frequencies, which makes it possible to achieve noise reduction and high speed information transfer.

Claims (2)

1. A phase modulator containing a power divider to which a carrier signal is applied, the first output of the power divider is connected to the first input of the first modulation block, and the second output of the divider is connected in series with the phase shift block and the first input of the second modulation block, and the output of the first modulation block is connected with the first input of the adder, the output of the second modulation block is connected to the second input of the adder, and the phase-modulated signal is obtained at the output of the adder, while the second inputs of both modulation blocks receive digital data from the same source, but before being fed to one of the modulation blocks, the digital data passes through logic inverter, characterized in that the carrier signal is a microwave signal with a frequency of 100-900 GHz, each modulation unit is an amplitude modulator with a waveguide input and output, the phase shift unit is made in the form of a passive delay line that provides a phase shift of 90 ° , the adder is made in the form of a quasi-optical bridge, moreover, the phase-modulated signal is taken from the first output of the quasi-optical bridge, while passing from the second input of the quasi-optical bridge to its first output, the intermediate signal receives an additional phase shift by 90°, and the second output of the quasi-optical bridge is connected to an unwanted signal absorber, and all microwave signals between blocks are transmitted using waveguides of the main section. 2. Phase modulator according to claim 1, characterized in that all amplitude modulators are resonator-type amplitude modulators.

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