Chirp delay line and pulse compression structure

Abstract

The invention belongs to the technical field of analog signal processing, and relates to a chirp delay line and a pulse compression structure. The chirp delay line comprises a dielectric substrate and a microstrip patch arranged on the dielectric substrate. The microstrip patch is of a strip-shaped structure, and the two ends of the microstrip patch are connected with the two sides of the dielectric substrate respectively. The micro-strip patch comprises a plurality of micro-strip units which are connected in sequence; the number of the microstrip units is calculated according to a target frequency range, and the width of the microstrip units is calculated according to the number of the microstrip units. According to the invention, microwave signals can be directly processed, and dispersion compensation is effectively realized while pulse compression is realized.

Description

Technical Field

[0001] The present application relates to the technical field of analog signal processing, and in particular to a chirped delay line and a pulse compression structure. Background Art

[0002] Pulse compression is a technique used to shorten the duration of a pulse without significantly changing the pulse amplitude or shape. The goal is to shorten the pulse duration and increase its peak power while maintaining or improving signal integrity. In optical fiber or other transmission media, different frequency components of a signal propagate at different speeds, resulting in pulse broadening. Pulse compression techniques help counteract these effects and maintain signal fidelity over long distances. In applications such as laser systems, radar, and telecommunications, high peak power outputs are often required. Shorter pulse durations enable the system to achieve higher peak powers without exceeding average power limits.

[0003] Due to the change in group velocity, different frequency components or modes of the electromagnetic signal arrive at the terminal at different times, causing the electromagnetic pulse to become broadened and resulting in distortion of the transmitted signal. This phenomenon is called pulse dispersion.

[0004] In the prior art, common chirped delay lines include surface acoustic wave chirped delay lines and Bragg fiber gratings. Among them, surface acoustic wave chirped delay lines are mostly used in the acoustic and ultrasonic frequency bands, and the operating frequency is relatively low. Bragg fiber gratings can generate chirped light pulses and are often used in signal waveform conversion systems based on microwave optoelectronic technology.

[0005] However, both chirped delay lines cannot directly process microwave signals and are difficult to apply to all-electronic analog signal processing systems. Summary of the invention

[0006] Based on this, it is necessary to provide a chirped delay line and pulse compression structure to address the above technical problems, which can directly process microwave signals and effectively achieve dispersion compensation while realizing pulse compression.

[0007] A chirped delay line comprises: a dielectric substrate and a microstrip patch arranged on the dielectric substrate; The microstrip patch is a strip-shaped structure, and two ends thereof are respectively connected to two sides of the dielectric substrate; The microstrip patch includes a plurality of microstrip units connected in sequence; the number of the microstrip units is calculated according to a target frequency range, and the width of the microstrip unit is calculated according to the number of the microstrip units.

[0008] In one embodiment, the number of microstrip units is calculated according to a target frequency range, including: Obtain the target frequency range and calculate the chirp coefficient; obtain the number of microstrip units based on the chirp coefficient.

[0009] In one embodiment, the width of the microstrip unit is calculated according to the number of microstrip units, including: Obtain the target frequency range and obtain the center frequency; obtain the length of the center microstrip unit on the microstrip patch according to the center frequency; obtain the length of the microstrip patch according to the length of the center microstrip unit on the microstrip patch and the number of microstrip units; According to the length of the microstrip patch, the characteristic impedance is calculated, and the corresponding relationship between the characteristic impedance and the coordinates of the microstrip unit is obtained; The width of each microstrip unit is obtained according to the corresponding relationship between the characteristic impedance and the microstrip unit coordinates and the corresponding relationship between the characteristic impedance and the width of the microstrip unit.

[0010] In one embodiment, according to the center frequency, the length of the center microstrip unit on the microstrip patch is obtained, including:

[0011] In the formula, is the center frequency, is the speed of light, is the length of the center microstrip unit on the microstrip patch, is the effective dielectric constant of the microstrip patch with a characteristic impedance of 50 Ω.

[0012] In one embodiment, the characteristic impedance is calculated according to the length of the microstrip patch, including:

[0013] in,

[0014] In the formula, For microstrip patch z Directional distribution of characteristic impedance; is an exponential function; is the length of the center microstrip unit on the microstrip patch; is the linear frequency modulation coefficient, when When the value is positive, the group delay slope of the delay line is positive. When it takes a negative value, the group delay slope of the delay line is negative; is the length of the microstrip patch; is the Gaussian distribution function; For microstrip patch z The microstrip unit coordinates in the direction. In one embodiment, the corresponding relationship between the characteristic impedance and the width of the microstrip unit includes:

[0015] In the formula, For microstrip patch z Directional distribution of characteristic impedance, is the relative dielectric constant of the dielectric substrate, is the thickness of the dielectric substrate, is the width of the microstrip unit, is the thickness of the microstrip patch.

[0016] In one embodiment, the microstrip patch is bent on the dielectric substrate to form an "S"-shaped structure.

[0017] A pulse compression structure comprises: an input end, an output end, a circulator and a chirped delay line; The first port of the circulator is connected to the input end, the second port of the circulator is connected to the chirped delay line, and the third port of the circulator is connected to the output end.

[0018] In one embodiment, it further includes: an amplifier; Two ends of the amplifier are connected to the input end and the first port of the circulator respectively.

[0019] In one embodiment, it further includes: a preprocessor; Two ends of the preprocessor are respectively connected to the input end and the amplifier to perform predistortion processing on the input analog signal.

[0020] The chirped delay line is designed with a microstrip patch as a microstrip line, and its conductive properties are used to form a specific circuit structure. Through the different widths and lengths of the microstrip patch, the signal is delayed and modulated, and the wide time domain signal is compressed into a narrow pulse in the time domain, which is conducive to achieving the desired pulse compression effect. It not only improves the peak gain of the signal, but also effectively reduces the time width of the signal, thereby improving the distance resolution capability and enhancing the signal-to-noise ratio. It not only maintains the detection distance of the radar, but also improves the resolution of the radar system and the energy of the transmitted signal. It is particularly suitable for signal processing of radar and sonar systems. At the same time, the chirped delay line is a signal processing device with nonlinear phase characteristics. It can introduce a specific time delay that changes linearly with frequency, and act as a matched filter to accurately offset the timing changes caused by dispersion. That is, while filtering, the signal can be dispersed and the waveform can be changed, which can effectively achieve dispersion compensation for analog signals, and offset the influence of dispersion by compressing the dispersed pulses back to their original shape, thereby maintaining the integrity of the transmitted information. It is particularly suitable for scenarios that require pulse compression, signal shaping and advanced communication systems. The present application designs a transmission type microwave chirped electromagnetic bandgap structure, i.e., a chirped delay line, which works in the microwave frequency band and has a linear group delay slope, by means of adjusting the characteristic impedance of a microstrip line. The chirped delay line effectively solves the technical challenge of high-power and high-resolution signal processing in radar target tracking by optimizing the design and innovating the microstrip line layout. The chirped delay line generates different delays according to the time positions of different frequency components in the signal. When the high-frequency component passes through, it will be delayed for a shorter time, while the low-frequency component will be delayed for a longer time. Thus, a chirped signal in a wide time domain can be compressed into a narrow pulse, thereby enhancing the resolution of the signal and stabilizing its characteristics. In addition, the chirped delay line is a two-dimensional planar structure, which is easy to integrate and has a large time slot bandwidth product. It can be used as a quadratic phase filter and can replace the dispersion circuit module in the analog signal waveform conversion system. It can also be used in the design of a matched filter system in a pulse compression radar receiver, providing an efficient and stable signal processing solution for radar applications, and has broad application prospects.

[0021] The above-mentioned pulse compression structure, as a dispersion device, is used for the generation of chirped pulses and dispersion compensation of pre-distorted signals, realizes the function of matched filtering, and improves the peak gain of the power amplifier output, realizes the nanosecond microwave pulse compression function of the input signal, and has broad application potential in radar target detection and long-distance communication in optical fiber networks. It is particularly suitable for scenarios where signal pulse compression is performed at the receiving end of the system, and can meet the requirements of long-distance and high-resolution for radar target tracking. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic diagram of a chirped delay line in one embodiment; Figure 2 is a schematic diagram of a pulse compression structure in one embodiment; Figure 3 is a simulation schematic diagram of a pulse compression structure in one embodiment; Figure 4 is a schematic diagram of a width distribution curve of a chirped delay line in a specific embodiment; Figure 5 is a schematic diagram of a group delay and S11 curve of a chirped delay line in a specific embodiment; Figure 6 is a schematic diagram of a time domain response curve of a chirped delay line in a specific embodiment; Figure 7 is a schematic diagram of a curve of input and output signals of an amplifier in a specific embodiment; Figure 8 It is a schematic diagram of a simulation result curve of a pulse compression structure in a specific embodiment.

[0023] Reference numerals: 001 dielectric substrate, 002 microstrip patch. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0025] It should be noted that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0026] In addition, the descriptions of "first", "second", etc. in this application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "multiple groups" means at least two groups, such as two groups, three groups, etc., unless otherwise clearly and specifically defined.

[0027] In this application, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0028] In addition, the technical solutions between the various embodiments of the present application can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0029] The present application provides a chirped delay line, such as Figure 1 As shown, in one embodiment, it includes: a dielectric substrate and a microstrip patch. The dielectric substrate is a plate-like structure and provides support for the microstrip patch.

[0030] The microstrip patch is a strip structure, which is arranged on a dielectric substrate, and its two ends are respectively connected to the two sides of the dielectric substrate; the microstrip patch includes a plurality of microstrip units connected in sequence; the number of microstrip units is calculated based on the target frequency range, and the width of the microstrip unit is calculated based on the number of microstrip units.

[0031] in: The number of microstrip units is calculated based on the target frequency range. Specifically, the target frequency range is obtained, and the chirp coefficient (ie, phase delay coefficient, linear frequency modulation coefficient) is calculated. The specific calculation method belongs to the existing technology; based on the chirp coefficient, the number of microstrip units is obtained.

[0032] The width of the microstrip unit is calculated based on the number of microstrip units, specifically: Obtain the target frequency range and obtain the center frequency. How to obtain the center frequency belongs to the prior art and will not be described in detail here. According to the center frequency, the length of the center microstrip unit on the microstrip patch is obtained:

[0033] In the formula, is the center frequency, is the speed of light, is the length of the center microstrip unit on the microstrip patch, is the effective dielectric constant of the microstrip patch with a characteristic impedance of 50 Ω; According to the length of the central microstrip unit on the microstrip patch and the number of microstrip units, the length of the microstrip patch is obtained:

[0034] In the formula, is the length of the microstrip patch, is the length of the center microstrip unit on the microstrip patch, is the number of microstrip units; According to the length of the microstrip patch, the characteristic impedance is calculated, and the corresponding relationship between the characteristic impedance and the microstrip unit coordinates is obtained:

[0035] in,

[0036] In the formula, For microstrip patch z Directional distribution of characteristic impedance; is an exponential function; is the length of the center microstrip unit on the microstrip patch; is the linear frequency modulation coefficient, when When the value is positive, the group delay slope of the delay line is positive. When it takes a negative value, the group delay slope of the delay line is negative; is the length of the microstrip patch; is the Gaussian distribution function; For microstrip patch z The microstrip unit coordinates in the direction; According to the thickness of the dielectric substrate and the thickness of the microstrip patch, the corresponding relationship between the characteristic impedance and the width of the microstrip unit is obtained:

[0037] In the formula, For microstrip patch z Directional distribution of characteristic impedance, is the relative dielectric constant of the dielectric substrate, is the thickness of the dielectric substrate, is the width of the microstrip unit, is the thickness of the microstrip patch; According to the corresponding relationship between the characteristic impedance and the microstrip unit coordinates and the corresponding relationship between the characteristic impedance and the width of the microstrip unit, the corresponding relationship between the coordinates and the width of each microstrip unit is obtained, and then the width of each microstrip unit is obtained.

[0038] Preferably, the microstrip patch is bent multiple times on the dielectric substrate to form an "S"-shaped structure, which can achieve miniaturization.

[0039] In this embodiment, the bandwidth that can be achieved by the chirped delay line is:

[0040] In the formula, is bandwidth; The total time delay that can be achieved by the chirped delay line is:

[0041] In the formula, is the total time delay.

[0042] It should be noted that the microstrip patch is made of metal material.

[0043] The chirped delay line is designed with a microstrip patch as a microstrip line, and its conductive properties are used to form a specific circuit structure. Through the different widths and lengths of the microstrip patch, the signal is delayed and modulated, and the wide time domain signal is compressed into a narrow pulse in the time domain, which is conducive to achieving the desired pulse compression effect. It not only improves the peak gain of the signal, but also effectively reduces the time width of the signal, thereby improving the distance resolution capability and enhancing the signal-to-noise ratio. It not only maintains the detection distance of the radar, but also improves the resolution of the radar system and the energy of the transmitted signal. It is particularly suitable for signal processing of radar and sonar systems. At the same time, the chirped delay line is a signal processing device with nonlinear phase characteristics. It can introduce a specific time delay that changes linearly with frequency, and act as a matched filter to accurately offset the timing changes caused by dispersion. That is, while filtering, the signal can be dispersed and the waveform can be changed, which can effectively achieve dispersion compensation for analog signals, and offset the influence of dispersion by compressing the dispersed pulses back to their original shape, thereby maintaining the integrity of the transmitted information. It is particularly suitable for scenarios that require pulse compression, signal shaping and advanced communication systems. The present application designs a transmission type microwave chirped electromagnetic bandgap structure, i.e., a chirped delay line, which works in the microwave frequency band and has a linear group delay slope, by adjusting the characteristic impedance of the microstrip line. The chirped delay line effectively solves the technical challenge of high-power and high-resolution signal processing in radar target tracking by optimizing the design and innovating the microstrip line layout. The chirped delay line generates different delays according to the time position of different frequency components in the signal. When the high-frequency component passes through, it will be delayed for a shorter time, while the low-frequency component will be delayed for a longer time, so that a chirped signal in a wide time domain can be compressed into a narrow pulse, thereby enhancing the resolution of the signal and stabilizing its characteristics. In addition, the chirped delay line is a two-dimensional planar structure, which is easy to integrate and has a large time slot bandwidth product. It can be used as a quadratic phase filter and can replace the dispersion circuit module in the analog signal waveform conversion system. It can also be used in the design of the matched filter system in the pulse compression radar receiver, providing an efficient and stable signal processing solution for radar applications, and has broad application prospects.

[0044] The present application also provides a pulse compression structure, such as Figure 2 As shown, in one embodiment, it includes: an input end, an output end, a circulator, and a chirped delay line. The first port of the circulator is connected to the input end, the second port of the circulator is connected to the chirped delay line, and the third port of the circulator is connected to the output end.

[0045] Preferably, it further comprises: an amplifier; that is, the pulse compression structure comprises: an input end, an output end, an amplifier, a circulator and a chirped delay line.

[0046] The two ends of the amplifier are connected to the input end and the first port of the circulator respectively; that is, the input end, the amplifier, the circulator and the chirped delay line are connected in sequence, and the circulator is also connected to the output end.

[0047] Further preferably, it further comprises: a preprocessor; that is, the pulse compression structure comprises: an input end, an output end, a preprocessor, an amplifier, a circulator and a chirped delay line.

[0048] The two ends of the preprocessor are respectively connected to the input end and the amplifier to perform predistortion processing on the input analog signal; that is, the input end, the preprocessor, the amplifier, the circulator and the chirped delay line are connected in sequence, and the circulator is also connected to the output end.

[0049] The working process of this embodiment is: the input end receives an external signal as an analog signal to be transmitted, and the analog signal to be transmitted enters the preprocessor in the form of a pulse to predistort the signal to obtain a predistorted signal, which can improve the processing effect of the signal in the power amplifier; then the signal passes through the amplifier (specifically the power amplifier) ​​to significantly amplify the amplitude of the predistorted signal to increase the energy of the transmitted signal, thereby enhancing the detection capability of the system; then the signal enters the circulator, which is an important component in the signal transmission process, and can achieve signal isolation and prevent the influence of signal reflection on system performance; the signal after power amplification is transmitted to the chirped delay line (CDL) structure through the second port of the circulator, a small part of the signal is lost, and most of the signal is reflected back and output by the third port of the circulator, obtaining an ideal pulse compression signal, and transmitting it through the output end, ensuring the integrity and stability of the signal. For example: in a radar system, the output end is connected to the radar receiving system, while in the experiment, the input end is connected to the pulse signal generator, and the output end is connected to the oscilloscope.

[0050] The above-mentioned pulse compression structure, as a dispersion device, is used for the generation of chirped pulses and dispersion compensation of pre-distorted signals, realizes the function of matched filtering, and improves the peak gain of the power amplifier output, realizes the nanosecond microwave pulse compression function of the input signal, and has broad application potential in radar target detection and long-distance communication in optical fiber networks. It is particularly suitable for scenarios where signal pulse compression is performed at the receiving end of the system, and can meet the requirements of long-distance and high-resolution for radar target tracking.

[0051] In a specific embodiment, on the chirped delay line, the dielectric substrate uses a composite material with a relative dielectric constant of 10.2 and a thickness of 1 mm (for example, a ceramic material with good electrical properties and mechanical strength, which can effectively support the transmission of high-frequency signals), which can obtain a greater dispersion delay.

[0052] like Figure 3 The simulation schematic diagram of the pulse compression structure is shown, where Vout1 is the signal output by the amplifier, Vout2 is the signal output by the pulse compression structure, and the pre-distorted signal enters the CDL after passing through the power amplifier. By combining the power amplifier and the CDL, the reflected signal can achieve a higher peak gain after compression.

[0053] like Figure 4 As shown, the line width of the microstrip line is determined by the chirp coefficient and the length of the microstrip line. It can be calculated that the phase delay coefficient of the microstrip patch is C=-1600 and the length is L =180 mm.

[0054] like Figure 5 As shown, the group delay slope of the chirped delay line (CDL) structure is -0.56 ns / GHz, the operating bandwidth is 2-6GHz, and the S11 and group delay response of the chirped delay line (CDL) structure are relatively flat, which is in line with the design expectations.

[0055] like Figure 6 As shown in Figure 1, the input signal is a short pulse of nanoseconds, which becomes wider in the time domain after passing through the CDL, indicating that dispersion has occurred.

[0056] like Figure 7 As shown, the system input signal is a linear frequency modulation signal with a frequency range of 2-6 GHz, and the power amplifier gain used is 15 dB. It should be noted that the CDL is simulated in the CST simulation software, and the S parameters of the simulation results are imported into the ADS simulation software to simulate the pulse compression structure.

[0057] like Figure 8 As shown in Figure 1, the input signal is pulse compressed by CDL, so that the peak gain of the amplifier output signal increases by 23 dB compared with the original signal.

[0058] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

[0059] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0060] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A chirped delay line, characterized in that: include: A dielectric substrate and a microstrip patch disposed on the dielectric substrate; The microstrip patch is a strip-shaped structure, and two ends thereof are respectively connected to two sides of the dielectric substrate; The microstrip patch includes a plurality of microstrip units connected in sequence; the number of the microstrip units is calculated according to a target frequency range, and the width of the microstrip unit is calculated according to the number of the microstrip units.

2. The chirped delay line according to claim 1, characterized in that: The number of microstrip units is calculated based on the target frequency range and includes: Obtain the target frequency range and calculate the chirp coefficient; obtain the number of microstrip units based on the chirp coefficient.

3. A chirped delay line according to claim 1 or 2, characterized in that: The width of the microstrip unit is calculated according to the number of microstrip units, including: Obtain the target frequency range and obtain the center frequency; obtain the length of the center microstrip unit on the microstrip patch according to the center frequency; obtain the length of the microstrip patch according to the length of the center microstrip unit on the microstrip patch and the number of microstrip units; According to the length of the microstrip patch, the characteristic impedance is calculated, and the corresponding relationship between the characteristic impedance and the coordinates of the microstrip unit is obtained; The width of each microstrip unit is obtained according to the corresponding relationship between the characteristic impedance and the microstrip unit coordinates and the corresponding relationship between the characteristic impedance and the width of the microstrip unit.

4. The chirped delay line according to claim 3, characterized in that: According to the center frequency, the length of the center microstrip unit on the microstrip patch is obtained, including: In the formula, is the center frequency, is the speed of light, is the length of the center microstrip unit on the microstrip patch, is the effective dielectric constant of the microstrip patch with a characteristic impedance of 50 Ω.

5. The chirped delay line according to claim 4, characterized in that: Based on the length of the microstrip patch, calculate the characteristic impedance, including: in, In the formula, For microstrip patch z Directional distribution of characteristic impedance; is an exponential function; is the length of the center microstrip unit on the microstrip patch; is the linear frequency modulation coefficient, when When the value is positive, the group delay slope of the delay line is positive. When it takes a negative value, the group delay slope of the delay line is negative; is the length of the microstrip patch; is the Gaussian distribution function; For microstrip patch z The microstrip unit coordinates in the direction.

6. The chirped delay line according to claim 5, characterized in that: The corresponding relationship between the characteristic impedance and the width of the microstrip unit includes: In the formula, For microstrip patch z Directional distribution of characteristic impedance, is the relative dielectric constant of the dielectric substrate, is the thickness of the dielectric substrate, is the width of the microstrip unit, is the thickness of the microstrip patch.

7. A chirped delay line according to claim 1 or 2, characterized in that: The microstrip patch is bent on the dielectric substrate to form an "S"-shaped structure.

8. A pulse compression structure, characterized in that: include: An input end, an output end, a circulator, and a chirped delay line as claimed in any one of claims 1 to 7; The first port of the circulator is connected to the input end, the second port of the circulator is connected to the chirped delay line, and the third port of the circulator is connected to the output end.

9. A pulse compression structure according to claim 8, characterized in that: Also includes: Amplifier; Two ends of the amplifier are connected to the input end and the first port of the circulator respectively.

10. A pulse compression structure according to claim 9, characterized in that: Also includes: Preprocessor; Two ends of the preprocessor are respectively connected to the input end and the amplifier to perform predistortion processing on the input analog signal.

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