Millimeter wave interferometer

Abstract

The invention discloses a millimeter wave interferometer, which belongs to an instrument in the technical field of electronic signal equipment, and adopts the technical scheme that a millimeter wave signal receiving and transmitting module is provided with two paths of phase-locked loops, and the two paths of phase-locked loops generate two paths of microwave signals through the input of reference clock signals; the two paths of microwave signals are respectively a driving signal of a transmitting channel and a driving signal of a receiving channel local oscillator; the transmission channel driving signal is subjected to power division after frequency multiplication filtering to generate two paths of millimeter wave signals, echoes of the two paths of millimeter wave signals are subjected to frequency mixing with a received local oscillator signal through a coupler, and two paths of intermediate frequency test signals are obtained; after IQ frequency mixing, the signal is transmitted and enters ADC sampling for analog-to-digital conversion, and the change of the density of the object to be tested can be tested through the phase change of the millimeter wave signal. According to the millimeter wave interferometer provided by the invention, the radial distribution of plasma electron density can be accurately tested, and the diagnosis cut-off density of plasma is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of electronic signal equipment, and in particular relates to a millimeter wave interferometer. Background Art

[0002] Plasma is a basic form of matter and the fourth form of matter besides solid, liquid and gas. Plasma is a complex multi-parameter system. Diagnosis of parameters such as electron density, collision frequency, electron temperature, active particle density, and electron energy distribution is an important task in plasma research. A typical microwave diagnostic method is microwave interferometry, which obtains information such as the electron density of the plasma by measuring the changes in parameters such as the amplitude and phase information of the microwave signal before and after passing through the plasma. In this method, since the antenna does not directly contact the plasma and the microwave power is very small when it is transmitted in the plasma, the characteristic parameters of the plasma are little affected when the plasma electron density is measured using a microwave interferometer, and it has a high time resolution, so transient measurements can be performed.

[0003] However, microwave single-channel interferometers are commonly used at present. This single-channel test method requires an estimated distribution density to obtain relatively accurate results. In addition, the microwave frequency band is lower than the increasingly high cutoff density of plasma diagnosis, and the test sensitivity of the microwave frequency band interferometer is low. Therefore, the test results of the current mainstream interferometer test equipment are rough, and the test sensitivity is relatively backward. Summary of the invention

[0004] The purpose of the present invention is to provide a millimeter wave interferometer, which increases the number of transmitting and receiving channels to 2 channels, and can collect electromagnetic wave change information at different radial positions of the plasma at the same time when the plasma electron density distribution is unknown, so as to realize accurate testing of the radial distribution of the plasma electron density; at the same time, the operating frequency of the transmitting signal and the receiving channel is increased to the millimeter wave Ka band, so as to improve the diagnostic cutoff density of the plasma.

[0005] The object of the present invention is achieved by a millimeter wave interferometer, comprising:

[0006] A signal acquisition module, wherein a crystal oscillator output in the signal acquisition module generates a reference clock signal;

[0007] A millimeter wave signal transceiver module for receiving reference clock signals and generating microwave signals; and

[0008] The millimeter wave signal transceiver module is provided with two phase-locked loops, and the two phase-locked loops generate two microwave signals through the input of the reference clock signal, and the two microwave signals are respectively the driving signal of the transmitting channel and the driving signal of the local oscillator of the receiving channel;

[0009] The transmitting channel driving signal is frequency-multiplied and filtered, and then power-divided to generate two millimeter wave signals. The echoes of the two millimeter wave signals are mixed with the receiving local oscillator signal through a coupler to obtain two intermediate frequency test signals.

[0010] The driving signal of the receiving channel local oscillator is mixed with the coupling signal of the transmitting channel output signal after frequency multiplication to obtain an intermediate frequency reference signal;

[0011] One intermediate frequency reference signal and two intermediate frequency test signals enter the signal acquisition module through the connector, and the signals are transmitted after IQ mixing and enter the ADC for sampling and analog-to-digital conversion. The change in the density of the object to be tested can be tested through the phase change of the millimeter wave signal.

[0012] Furthermore, the two millimeter wave signals are output through a coaxial connector.

[0013] Furthermore, the signal after analog-to-digital conversion by the ADC is sampled, and after digital signal processing, it is transmitted to the host computer through the serial port and the network port.

[0014] Furthermore, the signal operating frequency of the millimeter wave signal transceiver module is the millimeter wave Ka band.

[0015] Furthermore, after IQ mixing, two I signals and two Q signals are output.

[0016] Furthermore, the main body of the millimeter wave signal transceiver module is 280 mm long, 180 mm wide, and 40 mm high.

[0017] Furthermore, the signal acquisition module body has a length of 140 mm, a width of 80 mm, and a height of 15.5 mm.

[0018] Furthermore, the millimeter wave signal transceiver module body and the signal acquisition module body are both sealed aluminum cavities.

[0019] The beneficial effects of the present invention are embodied in:

[0020] In the present invention, the number of transmitting and receiving channels is increased to 2 channels, so that the electromagnetic wave change information at different radial positions of the plasma at the same time can be collected when the plasma electron density distribution is unknown, and the radial distribution of the plasma electron density can be accurately tested; at the same time, the operating frequency of the transmitting signal and the receiving channel is increased to the millimeter wave Ka band, thereby improving the diagnostic cutoff density of the plasma. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the specific embodiments or the description of the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0022] Figure 1 This is a top view of the main body of the millimeter wave signal transceiver module of the present invention;

[0023] Figure 2 This is a right side view of the main body of the millimeter wave signal transceiver module of the present invention;

[0024] Figure 3 This is a left view of the main body of the millimeter wave signal transceiver module of the present invention;

[0025] Figure 4 This is a top view of the main body of the signal acquisition module of the present invention;

[0026] Figure 5 This is a right side view of the main body of the signal acquisition module of the present invention;

[0027] Figure 6 This is a left view of the main body of the signal acquisition module of the present invention.

[0028] In the accompanying drawings, 1-millimeter wave signal transceiver module body, 2-millimeter wave signal transceiver channel 1, 3-intermediate frequency reference signal output channel, 4-millimeter wave signal transceiver channel 2, 5-intermediate frequency test signal output channel 1, 6-synchronous clock input channel, 7-intermediate frequency test signal output channel 2, 8-signal acquisition module body, 9-network port, 10-synchronous clock output interface, 11-serial port, 12-intermediate frequency test signal input interface, 13-intermediate frequency reference signal input interface, 14-intermediate frequency test signal input interface 2. DETAILED DESCRIPTION

[0029] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0030] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0031] Reference Figure 1-Figure 6 , a millimeter wave interferometer, comprising:

[0032] A signal acquisition module, wherein a crystal oscillator output in the signal acquisition module generates a reference clock signal;

[0033] A millimeter wave signal transceiver module for receiving reference clock signals and generating microwave signals; and

[0034] The millimeter wave signal transceiver module is provided with two phase-locked loops, and the two phase-locked loops generate two microwave signals through the input of the reference clock signal, and the two microwave signals are respectively the driving signal of the transmitting channel and the driving signal of the local oscillator of the receiving channel;

[0035] The transmitting channel driving signal is frequency-multiplied and filtered, and then power-divided to generate two millimeter wave signals. The echoes of the two millimeter wave signals are mixed with the receiving local oscillator signal through a coupler to obtain two intermediate frequency test signals.

[0036] The driving signal of the receiving channel local oscillator is mixed with the coupling signal of the transmitting channel output signal after frequency multiplication to obtain an intermediate frequency reference signal;

[0037] One intermediate frequency reference signal and two intermediate frequency test signals enter the signal acquisition module through the connector, and the signals are transmitted after IQ mixing and enter the ADC for sampling and analog-to-digital conversion. The change in the density of the object to be tested can be tested through the phase change of the millimeter wave signal.

[0038] As a preferred embodiment of this embodiment, in the signal acquisition module, the crystal oscillator outputs an electrical signal through a crystal oscillator. Figure 5 In the embodiment, the reference clock signal generated by the crystal oscillator output is output through the synchronous clock output interface 10 provided on one side of the signal acquisition module body 8.

[0039] The crystal oscillator (Crystal Oscillator) is an electronic oscillator circuit that uses a quartz crystal as a resonant element, and it uses the piezoelectric effect of the quartz crystal to generate an electrical signal with a very precise frequency. Crystal oscillators have advantages such as high stability, quality factor, small size and low cost, which makes them superior to other resonators such as LC circuits, ceramic resonators, forks, etc. Crystal oscillators play a vital role in electronic circuits, providing stable clock signals for various electronic devices to ensure the precise operation of the equipment.

[0040] The working principle of the crystal oscillator is based on the piezoelectric effect of quartz crystal, that is, when an electric field is applied to the two electrodes of the quartz crystal, the crystal will produce mechanical deformation; conversely, if mechanical pressure is applied to both ends of the crystal, the crystal will generate an electric field. This phenomenon is reversible. By using this characteristic, when an alternating voltage is applied to both ends of the crystal, the crystal will produce mechanical vibration and an alternating electric field at the same time. Under certain conditions, this vibration and electric field will reach a specific frequency, namely the piezoelectric resonance frequency, making the frequency of the oscillator very stable.

[0041] The phase-locked loop is a negative feedback control system that uses the voltage generated by phase synchronization to tune the voltage-controlled oscillator to generate the target frequency. The frequency and phase of the oscillation signal inside the loop are controlled by an external reference signal to achieve automatic tracking of the output signal frequency to the input signal frequency, and is generally used in a closed-loop tracking circuit. It is a method of making the frequency more stable in radio transmission, mainly including VCO (voltage-controlled oscillator) and PLL (phase-locked loop). The voltage-controlled oscillator gives a signal, one part of which is used as output, and the other part is compared with the local oscillator signal generated by the PLL through frequency division. In order to keep the frequency unchanged, the phase difference is required not to change. If there is a change in the phase difference, the voltage at the voltage output end of the PLL changes to control the VCO until the phase difference is restored to achieve the purpose of phase locking. A closed-loop electronic circuit that can keep the frequency and phase of the controlled oscillator in a certain relationship with the input signal.

[0042] Preferably, the two millimeter wave signals are output through a coaxial connector.

[0043] As a preferred mode of this embodiment, the two millimeter wave signals are output or input through two millimeter wave signal transceiver channels arranged on one side of the millimeter wave signal transceiver module body 1. The two millimeter wave signal transceiver channels are millimeter wave signal transceiver channel 1 and millimeter wave signal transceiver channel 2 respectively.

[0044] The intermediate frequency reference signal is output through the intermediate frequency reference signal output channel 3 arranged between the two millimeter wave signal transceiver channels.

[0045] The two intermediate frequency test signals are output through two intermediate frequency test signal output channels arranged on one side of the millimeter wave signal transceiver module body 1 relative to the intermediate frequency reference signal output channel 3 .

[0046] The signal of the synchronous clock output interface is transmitted through the synchronous clock input channel 6 provided on the millimeter wave signal transceiver module body 1, and the synchronous clock input channel 6 is provided between two intermediate frequency test signal output channels. The two intermediate frequency test signal output channels are intermediate frequency test signal output channel 1 and intermediate frequency test signal output channel 2.

[0047] Preferably, the signal after analog-to-digital conversion by the ADC is sampled, and after digital signal processing, it is transmitted to the host computer through the serial port and the network port.

[0048] Reference Figure 4 and Figure 5 In the signal acquisition module body 8 , the network port 9 is arranged on one side of the synchronous clock output interface 10 , and the serial port 11 is arranged on the side opposite to the synchronous clock output interface 10 .

[0049] The two IF test signals are input through an IF test signal input interface 12 disposed at one side of the serial port 11 , and the IF reference signal is input through an IF reference signal input interface 13 disposed between the two IF test signal input interfaces 12 .

[0050] Preferably, the signal operating frequency of the millimeter wave signal transceiver module is the millimeter wave Ka band. The Ka band is a part of the microwave band of the electromagnetic spectrum, and the frequency range of the Ka band is 26.5-40 GHz.

[0051] Preferably, two I signals and two Q signals are output after IQ mixing.

[0052] As a preferred embodiment of this embodiment, the IQ mixer is a double-balanced mixer, which can be used for down-conversion to generate baseband I and Q signals, and can also be used as an image rejection mixer for up-conversion to up-convert the baseband I and Q signals into single-sideband modulated signals; a broadband 90° bridge and a broadband in-phase power divider are connected to the double-balanced mixer; the broadband in-phase power divider is used to realize in-phase power division of the input RF signal and output two RF signals with consistent amplitudes; the broadband 90° bridge is used to realize orthogonal output of the local oscillator signal.

[0053] Preferably, the millimeter wave signal transceiver module body has a length of 280 mm, a width of 180 mm, and a height of 40 mm.

[0054] Preferably, the signal acquisition module body has a length of 140 mm, a width of 80 mm and a height of 15.5 mm.

[0055] Preferably, the millimeter wave signal transceiver module body and the signal acquisition module body are both sealed aluminum cavities.

[0056] Working principle and working process of the present invention:

[0057] When the millimeter interferometer provided by the present invention is working, the signal acquisition module, the crystal oscillator output in the signal acquisition module generates a reference clock signal;

[0058] A millimeter wave signal transceiver module is used for receiving a reference clock signal and generating a microwave signal; and the millimeter wave signal transceiver module is provided with two phase-locked loops, and the two phase-locked loops generate two microwave signals through the input of the reference clock signal, and the two microwave signals are respectively a driving signal of a transmitting channel and a driving signal of a local oscillator of a receiving channel;

[0059] The transmitting channel driving signal is frequency-multiplied and filtered, and then power-divided to generate two millimeter wave signals. The two millimeter wave signals are output through a coaxial connector. The output signals can be radiated to the object under test through an antenna feed line. After being transmitted in the medium of the object under test, the echoes of the two millimeter wave signals are mixed with the receiving local oscillator signal through a coupler to obtain two intermediate frequency test signals.

[0060] The driving signal of the receiving channel local oscillator is mixed with the coupling signal of the transmitting channel output signal after frequency multiplication to obtain an intermediate frequency reference signal;

[0061] One intermediate frequency reference signal and two intermediate frequency test signals enter the signal acquisition module through the connector, undergo IQ mixing and then transmit the signal, enter the ADC for sampling, perform analog-to-digital conversion and acquisition, and send it to the host computer through the serial port. The host computer can record the changes in IQ to characterize the amplitude and phase changes of the millimeter wave signal; and the phase change of the millimeter wave signal can test the change in the density of the object to be tested.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A millimeter wave interferometer, characterized in that: include: A signal acquisition module, wherein a crystal oscillator output in the signal acquisition module generates a reference clock signal; Millimeter wave signal transceiver module, used for receiving reference clock signals and generating microwave signals; as well as The millimeter wave signal transceiver module is provided with two phase-locked loops, and the two phase-locked loops generate two microwave signals through the input of the reference clock signal, and the two microwave signals are respectively the driving signal of the transmitting channel and the driving signal of the local oscillator of the receiving channel; The transmitting channel driving signal is frequency-multiplied and filtered, and then power-divided to generate two millimeter wave signals. The echoes of the two millimeter wave signals are mixed with the receiving local oscillator signal through a coupler to obtain two intermediate frequency test signals. The driving signal of the receiving channel local oscillator is mixed with the coupling signal of the transmitting channel output signal after frequency multiplication to obtain an intermediate frequency reference signal; One intermediate frequency reference signal and two intermediate frequency test signals enter the signal acquisition module through the connector, and the signals are transmitted after IQ mixing and enter the ADC for sampling and analog-to-digital conversion. The change in the density of the object to be tested can be tested through the phase change of the millimeter wave signal.

2. The millimeter wave interferometer according to claim 1, characterized in that: The two millimeter wave signals are output through a coaxial connector.

3. The millimeter wave interferometer according to claim 1, characterized in that: The signal is sampled after entering the ADC analog-to-digital conversion, and then transmitted to the host computer through the serial port and network port after digital signal processing.

4. The millimeter wave interferometer according to claim 1, characterized in that: The signal operating frequency of the millimeter wave signal transceiver module is the millimeter wave Ka band.

5. The millimeter wave interferometer according to claim 1, characterized in that: After IQ mixing, two I signals and two Q signals are output.

6. The millimeter wave interferometer according to claim 1, characterized in that: The main body of the millimeter wave signal transceiver module is 280 mm long, 180 mm wide and 40 mm high.

7. The millimeter wave interferometer according to claim 1, characterized in that: The signal acquisition module body has a length of 140 mm, a width of 80 mm, and a height of 15.5 mm.

8. The millimeter wave interferometer according to claim 1, characterized in that: The millimeter wave signal transceiver module body and the signal acquisition module body are both sealed aluminum cavities.

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