Terahertz amplitude direct modulator using resonant ring absorption echo and modulation method

Abstract

The application discloses a terahertz amplitude direct modulator using resonant ring to absorb echo and a modulation method, relates to the technical field of electromagnetic functional devices, and solves the problem that the prior art cannot present a low standing wave ratio while maintaining a low insertion loss. The application comprises an active material control structure, which comprises a microstrip transmission main circuit, a microstrip ring control branch, a low-pass filter feed input circuit and a low-pass filter feed ground circuit connected in sequence. The application adopts an active device embedded in a ring-shaped microstrip structure in structure, and realizes terahertz wave regulation and control by controlling the bias voltage of the active device. In the working frequency band, the application can realize the effect that both the on and off states of the conventional direct modulator present a low reflection coefficient, greatly reduces the standing wave reflected to the previous stage when the direct modulator works, protects the previous stage components, and thus improves the working stability and reliability of the whole communication system.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic functional devices, and more specifically to a terahertz amplitude direct modulator and modulation method that utilizes a resonant ring to absorb echoes. Background Technology

[0002] With the rapid development of modern society, people's demand for high-speed information transmission is increasing, and terahertz waves with extremely high frequencies are one of the key research areas for future applications in high-speed communication. Terahertz amplitude direct modulators are one of the important components of terahertz wireless communication systems.

[0003] Currently, the design concept of terahertz amplitude direct modulators is to change the impedance characteristics of active devices by controlling the input voltage of the active devices, thereby controlling the conduction or isolation of the microstrip transmission line for the transmitted signal, thus achieving signal modulation. To meet the demands of high-speed information transmission, terahertz direct modulators not only require low insertion loss, a large switching ratio, and a certain operating frequency bandwidth, but also, to minimize the impact of reflected waves from the direct modulator on the frequency multiplier, which is also used in terahertz wireless communication systems and cascaded with the terahertz direct modulator, the direct modulator needs to exhibit a low standing wave ratio (VSWR) in both the conduction and isolation states of the modulated signal.

[0004] Traditional direct modulators are based on the reflection principle, which means that the isolation of the control signal is achieved by completely reflecting the signal back to the input port. This type of modulator feeds the input signal back to the front-end components of the system. A large amount of reflected signal can affect the performance of the front-end components and may even cause irreversible damage to them, thus affecting the stability of the entire communication system. Therefore, traditional reflection-based direct modulators are difficult to meet the stability requirements of terahertz communication systems. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention aims to provide a terahertz amplitude direct modulator and modulation method that utilizes a resonant ring to absorb echoes, thereby solving the problem that the prior art cannot maintain a low insertion loss while exhibiting a low standing wave ratio.

[0006] A terahertz amplitude direct modulator utilizing a resonant ring to absorb echoes includes an active material control structure. This active material control structure comprises a microstrip transmission backbone circuit, a microstrip ring control branch, a low-pass filter feed input circuit, and a low-pass filter feed grounding circuit, connected in sequence. The low-pass filter feed input circuit feeds power to the microstrip ring control branch, which in turn controls the switching of the terahertz waves in the microstrip transmission backbone circuit based on the feed conditions. The microstrip transmission backbone circuit transmits terahertz waves, and the low-pass filter feed grounding circuit provides grounding.

[0007] Preferably, the microstrip ring control branch includes a gallium arsenide diode, a microstrip ring assembly, and a microstrip matching structure. The microstrip ring assembly is divided into two parts. One part of the microstrip ring assembly is connected to one side of the gallium arsenide diode at one end and to the microstrip transmission backbone circuit at the other end. The other part of the microstrip ring assembly is connected to the other side of the gallium arsenide diode at one end and to the microstrip matching structure at the other end. The microstrip ring assembly, the gallium arsenide diode connected thereto, and the microstrip transmission backbone circuit together form a ring structure in physical space. The gallium arsenide diode is connected to the microstrip ring assembly and is connected in parallel to the microstrip transmission backbone circuit through the microstrip ring assembly. At the same time, it is grounded through the low-pass filter feed grounding circuit and fed to the gallium arsenide diode through the low-pass filter feed input circuit.

[0008] Preferably, it further includes an input waveguide-microstrip line transition structure and a microstrip line-output waveguide transition structure, with one end of the microstrip transmission backbone circuit connected to the input waveguide-microstrip line transition structure and the other end connected to the microstrip line-output waveguide transition structure.

[0009] Preferably, the low-pass filter power input circuit includes a power feed metal line, a CMRC low-pass filter, and a power feed metal plate. One end of the power feed metal line is connected to the CMRC low-pass filter, and the other end is connected to the microstrip ring control branch. The CMRC low-pass filter is connected to the power feed metal plate and is powered through the power feed metal plate. The low-pass filter power grounding circuit includes a grounding metal line, a CMRC low-pass filter, and a grounding metal plate. The grounding metal plate is connected to the waveguide cavity wall to achieve grounding. One end of the microstrip transmission backbone circuit is connected to the input waveguide-microstrip line transition structure, and the other end is connected to the microstrip line-output waveguide transition structure.

[0010] Preferably, in addition to one end being connected to one end of the microstrip transmission backbone circuit, the other end of the input waveguide-microstrip line transition structure is used to feed terahertz waves; in addition to one end being connected to one end of the microstrip transmission backbone circuit, the other end of the microstrip line-output waveguide transition structure is used to output terahertz waves.

[0011] Preferably, the shape and size of the microstrip control branch in the design affect the operating frequency band of the echo absorption. The sum of the lengths of the microstrip ring assembly used in this invention and the microstrip transmission backbone circuit that participates in forming the ring structure is near a positive integer multiple of half the wavelength. The electrical length, characteristic impedance of the microstrip line of the microstrip control branch, and the impedance characteristics of the Schottky diode itself all affect the operating frequency band of the echo absorption.

[0012] Preferably, the shape of the microstrip ring component, gallium arsenide diode, and corresponding part of the microstrip transmission backbone circuit in the microstrip ring control branch is not limited to a circular ring, and the combined shape can also be a square ring or other closed loop structure.

[0013] Preferably, the microstrip matching structure in the microstrip ring control branch includes, but is not limited to, a fan-shaped microstrip, or any microstrip line that can form a microstrip branch, such as a branched straight microstrip line.

[0014] Preferably, the substrate material used is one or more of gallium arsenide, silicon dioxide, high-resistivity silicon, sapphire, and silicon carbide. A method for direct modulation of terahertz amplitude using a resonant ring to absorb echoes includes the following steps:

[0015] Step 1: Terahertz waves are fed in through the input waveguide and pass through the E-plane probe in the input waveguide-microstrip line transition structure to realize the conversion of the electromagnetic field mode of the waveguide to the electromagnetic field mode of the microstrip line.

[0016] Step 2: The terahertz wave is input to the microstrip transmission backbone circuit of the active material control structure, and the impedance state of the gallium arsenide diode is controlled by different voltages fed by the low-pass filter power input circuit.

[0017] Step 2.1: When the feed voltage is the on-bias voltage, the impedance effect of the microstrip ring control branch enables the two ports of the microstrip transmission backbone circuit to conduct terahertz waves. In the on-state, the designed microstrip ring control branch size, combined with the high series resistance of the diode equivalent, enables the microstrip transmission backbone circuit to exhibit good transmission characteristics, while achieving low insertion loss and low port reflection coefficient. The direct modulator exhibits a low reflection coefficient in both the on-state and the isolation state. Step 2.2: When the feed voltage is the isolation bias voltage, the impedance effect of the microstrip ring control branch enables the two ports of the microstrip transmission backbone circuit to isolate terahertz waves. Due to the structural characteristics of the microstrip ring control branch, in the isolation state, the reflected wave at the port is bifurcated through the multi-path branch of the microstrip ring control branch, so that the reflected wave is canceled out in phase within the multi-path of the microstrip ring control branch, thus exhibiting low standing wave characteristics at the input port.

[0018] Step 3: When the two ports of the microstrip transmission backbone circuit are turned on for terahertz waves, the terahertz waves are output through the microstrip line-output waveguide transition structure.

[0019] The beneficial effects of this invention include:

[0020] Compared to traditional terahertz direct modulators, this invention employs an active device embedded in a ring microstrip structure. Terahertz wave modulation is achieved by controlling the bias voltage of the active device. In the on-state, the designed microstrip ring control branch size, combined with the high series resistance of the diode equivalent, results in better transmission characteristics for the microstrip transmission backbone circuit. Simultaneously, it achieves low insertion loss and low port reflection coefficient. This direct modulator exhibits low reflection coefficients in both on- and isolated states. Due to the structural characteristics of the microstrip ring control branch, in the isolated state, the reflected wave at the port undergoes multi-path bifurcation via the microstrip ring control branch, resulting in anti-phase cancellation within the multiple paths of the microstrip ring control branch. This leads to low standing wave characteristics at the input port. Within the operating frequency band, it achieves a low reflection coefficient effect in both on- and isolated states, which is unattainable by traditional direct modulators. This significantly reduces the standing wave reflected to the preceding stage during direct modulator operation, protecting the preceding components and thus improving the overall stability and reliability of the communication system. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of a terahertz amplitude direct modulator that utilizes a resonant ring to absorb the echo.

[0022] Figure 2 A top view of a terahertz amplitude direct modulator structure that utilizes a resonant ring to absorb echoes.

[0023] Figure 3 This is a schematic diagram of an active material control structure.

[0024] Figure 4 This is a schematic diagram of a microstrip loop control branch structure.

[0025] Figure 5 The diagram shows the S21 parameters under the two states of conduction / isolation involved in Example 1.

[0026] Figure 6 The diagram shows the S11 parameters under the two states of conduction / isolation involved in Example 1.

[0027] Figure Labels

[0028] 1-Input waveguide microstrip line transition structure, 2-Active material control structure, 3-Microstrip line output waveguide transition structure, 21-Low-pass filter feed input circuit, 22-Microstrip ring control branch, 23-Microstrip transmission backbone circuit, 24-Low-pass filter feed grounding circuit, 221-Fan-shaped microstrip matching structure, 222-Microstrip ring component part I, 223-Gallium arsenide diode, 224-Microstrip ring component part II. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0030] The following is in conjunction with the appendix Figure 1-6 Specific embodiments of the present invention will be described in detail;

[0031] Example 1

[0032] like Figures 1-4 As shown, a terahertz amplitude direct modulator utilizing a resonant ring to absorb echoes includes an input waveguide microstrip line transition structure 1, an active material control structure 2, and a microstrip line output waveguide transition structure 3. The active material control structure 2 includes a microstrip transmission backbone circuit 23, a microstrip ring control branch 22, a low-pass filter feed input circuit 21, and a low-pass filter feed grounding circuit 24. The microstrip ring control branch 22 includes a gallium arsenide diode 223, a microstrip ring component section I222, a microstrip ring component section I224, and a fan-shaped microstrip matching structure 221. The microstrip ring component section I... One end of I224 is connected to one side of the gallium arsenide diode 223, and the other end is connected to the microstrip transmission backbone circuit 23. One end of the microstrip ring assembly I222 is connected to the other side of the gallium arsenide diode 223, and the other end is connected to the microstrip matching structure. The microstrip ring assembly, the gallium arsenide diode 223 connected thereto, and the microstrip transmission backbone circuit 23 together form a ring structure in physical space. The sum of the lengths of the microstrip ring assembly and the microstrip transmission backbone circuit 23 that participates in forming the ring structure is near a positive integer multiple of half the wavelength.

[0033] The top of the microstrip ring component I222 has a ring structure. The gallium arsenide diode 223 is embedded between the microstrip ring component I222 and the microstrip ring component I224. The microstrip ring component I222... I224 is connected in parallel to the microstrip transmission backbone circuit 23, and is grounded through the low-pass filter feed grounding circuit 24 and fed through the low-pass filter feed input circuit 21. The fan-shaped center of the fan-shaped microstrip matching structure 221 is located on the microstrip ring assembly part I222. The low-pass filter feed input circuit 21 includes a feed metal line, a CMRC low-pass filter, and a feed metal plate. One end of the feed metal line is connected to the CMRC low-pass filter, and the other end is connected to the microstrip ring control branch 22. The CMRC low-pass filter is connected to the feed metal plate and fed through the feed metal plate. The low-pass filter feed grounding circuit 24 includes a grounding metal line, a CMRC low-pass filter, and a grounding metal plate. The grounding metal plate is connected to the waveguide cavity wall to achieve grounding. One end of the microstrip transmission backbone circuit 23 is connected to the input waveguide microstrip line transition structure 1, and the other end is connected to the microstrip line output waveguide transition structure 3.

[0034] The substrate material used in this example is gallium arsenide, and the metal structure is made of gold.

[0035] Example 2

[0036] like Figures 5-6As shown, the direct modulation method of terahertz amplitude using resonant ring absorption of echo specifically includes: terahertz waves are fed into an input waveguide, and the electromagnetic field mode of the waveguide is converted to the electromagnetic field mode of the microstrip line through the E-plane probe in the microstrip line transition structure 1. The waves are then input to the microstrip transmission backbone circuit 23 of the active material control structure 2. The impedance state of the gallium arsenide diode 223 is controlled by different feed voltages. When the feed voltage is the diode's zero bias voltage, the impedance effect of the microstrip ring control branch 22 allows the two ports of the microstrip transmission backbone circuit 23 to conduct the terahertz waves. When the feed voltage is the diode's conduction voltage, the impedance effect of the microstrip ring control branch 22 allows the two ports of the microstrip transmission backbone circuit 23 to conduct the terahertz waves. In isolation, due to the structural characteristics of the microstrip ring control branch 22, the reflected wave at the port is bifurcated through multiple paths of the microstrip ring control branch 22 in the isolation state, so that the reflected wave is antiphase canceled within the multiple paths of the microstrip ring control branch 22, thus exhibiting low standing wave characteristics at the input port. In the conduction state, the designed size of the microstrip ring control branch 22, combined with the high series resistance of the diode equivalent, makes the microstrip ring control branch 22 and the microstrip transmission backbone circuit 23 approximately equivalent to a pure microstrip line equivalent circuit model, thus exhibiting good transmission characteristics. The good transmission characteristics also result in a low reflection coefficient at the port. That is, the modulator achieves low insertion loss in the conduction state and low port reflection coefficient in both conduction and isolation states.

[0037] The simulation of the terahertz amplitude direct modulator using a resonant ring to absorb the echo in this example yielded good results and demonstrates high feasibility. This example simulates the conduction and cutoff states of the circuit to terahertz waves when actually fed by a gallium arsenide diode 223 by varying its voltage-controlled resistor. Simulations were performed in the 200-235 GHz frequency band, and the S-parameter simulation results are as follows: Figure 5 , Figure 6 As shown, the modulator exhibits a switching ratio greater than 10dB between 215-225GHz, with a switching ratio greater than 27dB at 220GHz, and an insertion loss less than 2dB. Simultaneously, the input port reflection coefficient in both on / off states between 200-227GHz is less than -14.5dB, meaning it has fewer reflected waves over a large bandwidth, thus exhibiting low VSWR characteristics. Furthermore, the feeding circuit of this invention allows for real-time control of the gallium arsenide diode 223 active material structure, enabling high-speed terahertz amplitude modulation. By selecting a suitable operating frequency band, a direct terahertz amplitude modulator utilizing a resonant ring to absorb the echo can achieve low insertion loss, high switching ratio, and low VSWR characteristics, making it suitable for high-stability, high-speed terahertz communication systems.

[0038] Example 3

[0039] The difference between this embodiment and Embodiment 1 is that the top of the microstrip ring component I222 in the microstrip ring control branch 22 is a square structure, and the microstrip matching structure is a branched straight microstrip line.

[0040] Example 4

[0041] The difference between this embodiment and embodiment 1 is that the active material control structure 2 includes two parallel microstrip ring control branches 22.

[0042] The embodiments described above merely illustrate specific implementation methods of this application, and while the descriptions are detailed and specific, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the technical solution of this application, and these modifications and improvements all fall within the scope of protection of this application.

Claims

1. A terahertz amplitude direct modulator that utilizes a resonant ring to absorb echoes, characterized in that, The active material control structure (2) includes a low-pass filter power supply input circuit (21), a microstrip ring control branch (22), a microstrip transmission backbone circuit (23), and a low-pass filter power supply grounding circuit (24) connected in sequence. The low-pass filter power supply input circuit (21) is used to power the microstrip ring control branch (22). The microstrip ring control branch (22) is used to switch the microstrip transmission backbone circuit (23) on and off at terahertz according to the power supply. The microstrip transmission backbone circuit (23) is used to transmit terahertz waves. The low-pass filter power supply grounding circuit (24) is used to ground. The microstrip ring control branch (22) includes a gallium arsenide diode (223), a microstrip ring assembly, and a microstrip matching structure. The gallium arsenide diode (223) is embedded in the microstrip ring assembly and connected in parallel to the microstrip transmission backbone circuit (23) through the microstrip ring assembly. At the same time, it is grounded through the low-pass filter feed grounding circuit (24). The low-pass filter feed input circuit (21) feeds the gallium arsenide diode (223). One end of the microstrip matching structure is located on the microstrip ring, and the other end of the microstrip matching structure is connected to the low-pass filter feed input circuit (21). The microstrip ring assembly includes a microstrip ring assembly part I (222) and a microstrip ring assembly part II (224). One end of the microstrip ring assembly part II (224) is connected to one side of the gallium arsenide diode (223), and the other end is connected to the microstrip transmission backbone circuit (23). One end of the microstrip ring assembly part I (222) is connected to the other side of the gallium arsenide diode (223), and the other end is connected to the microstrip matching structure. The microstrip ring assembly, the gallium arsenide diode (223) connected thereto, and the microstrip transmission backbone circuit (23) together form a ring structure in physical space.

2. The terahertz amplitude direct modulator utilizing a resonant ring to absorb echoes according to claim 1, characterized in that, It also includes an input waveguide microstrip line transition structure (1) and a microstrip line output waveguide transition structure (3). One end of the microstrip transmission backbone circuit (23) is connected to the input waveguide microstrip line transition structure (1), and the other end is connected to the microstrip line output waveguide transition structure (3).

3. The terahertz amplitude direct modulator utilizing a resonant ring to absorb echoes according to claim 1, characterized in that, The low-pass filter power input circuit (21) includes a power supply metal line, a first CMRC low-pass filter, and a power supply metal plate. One end of the power supply metal line is connected to the power supply metal plate and is powered through the power supply metal plate. The other end of the power supply metal line is connected to the microstrip ring control branch (22), and the first CMRC low-pass filter is provided on the power supply metal line. The low-pass filter power supply grounding circuit (24) includes a grounding metal line, a second CMRC low-pass filter, and a grounding metal plate. One end of the grounding metal line is connected to the grounding metal plate and is grounded through the grounding metal plate connected to the waveguide cavity wall. The other end of the grounding metal line is connected to the microstrip transmission backbone circuit (23), and the second CMRC low-pass filter is provided on the grounding metal line.

4. The terahertz amplitude direct modulator utilizing a resonant ring to absorb echoes according to claim 1, characterized in that, The sum of the lengths of the microstrip ring assembly and the microstrip transmission backbone circuit (23) that participates in forming the ring structure is near a positive integer multiple of half the wavelength.

5. The terahertz amplitude direct modulator utilizing a resonant ring to absorb echoes according to claim 1, characterized in that, The shape of the microstrip ring component in the microstrip ring control branch (22), together with the gallium arsenide diode (223) and the microstrip transmission backbone circuit (23), includes circular ring and square ring.

6. The terahertz amplitude direct modulator utilizing a resonant ring to absorb echoes according to claim 1, characterized in that, The microstrip matching structure in the microstrip ring control branch (22) includes fan-shaped microstrip and branched straight microstrip line.

7. The terahertz amplitude direct modulator utilizing a resonant ring to absorb echoes according to claim 1, characterized in that, The substrate material used is one or more of gallium arsenide, silicon dioxide, high-resistivity silicon, sapphire, and silicon carbide.

8. A method for direct modulation of terahertz amplitude using a resonant ring to absorb echoes, characterized in that, The terahertz amplitude direct modulator based on the resonant ring absorbing the echo, as described in any one of claims 1 to 7, comprises the following steps: Step 1: Terahertz waves are fed in through the input waveguide and the electromagnetic field mode of the waveguide is converted to the electromagnetic field mode of the microstrip line through the microstrip line transition structure (1). Step 2: The terahertz wave is input to the microstrip transmission backbone circuit (23) of the active material control structure (2), and the impedance state of the gallium arsenide diode (223) is controlled by different voltages fed by the low-pass filter power input circuit (21); Step 2.1: When the feed voltage is the conduction bias voltage, the impedance effect of the microstrip loop control branch (22) enables the two ports of the microstrip transmission backbone circuit (23) to conduct terahertz waves. Step 2.2: When the feed voltage is the isolation bias voltage, the impedance effect of the microstrip loop control branch (22) enables the two ports of the microstrip transmission backbone circuit (23) to isolate the terahertz wave; Step 3: When the two ports of the microstrip transmission backbone circuit (23) are turned on for terahertz waves, the terahertz waves are output through the microstrip line output waveguide transition structure (3).

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