A 3dB 180° coupler for terahertz communication tracking system

Abstract

The invention discloses a 90° phase shifter and a 3dB180° coupler for a terahertz communication tracking system, relates to the technical field of terahertz communication tracking, and solves the technical problem that the existing phase shifter cannot realize phase shifting in the terahertz low frequency band and is not convenient for integration; the invention comprises a waveguide, a first structure and a second structure, the first structure comprises a first step recessed inwardly arranged on the narrow side of the waveguide, and the second structure comprises a second step protruding outwardly arranged on the wide side of the waveguide; the 90° phase shifter designed by the invention is simpler to process, avoids excessive pin phase shifting of the traditional phase shifter, reduces the processing error, and makes broadband phase shifting in the terahertz frequency band possible.

Description

Technical Field

[0001] The invention relates to the technical field of terahertz communication tracking, and in particular to a 90° phase shifter and a 3dB180° coupler used in a terahertz communication tracking system. Background Art

[0002] We have now entered the 5G era from the 4G era, and will be facing the 6G era in the future, and terahertz communication is an important part of 6G. The terahertz frequency band is between 0.1THz and 10THz, and the spectrum resources are wide, which can be used for high-speed communication. However, terahertz communication has the characteristics of high spatial loss and strong absorption of atmospheric molecules in space transmission. In order to maintain good communication performance, the transmitter needs to have a higher output power. In addition to the power requirements of the antenna front-end output, the antenna needs to have a higher gain in order to have a higher transmission efficiency in the entire wireless transmission link. The problem brought by high gain is narrow beam. In the process of communication, the problem of difficult alignment of the transmitting and receiving antennas and the further development of target tracking problems appear.

[0003] One solution to the above problem is the single pulse tracking technology, because as a precise tracking method, the single pulse tracking technology can play a good role in solving the above problem. This technology contains a device that directly affects the tracking accuracy - the single pulse antenna. The single pulse antenna specifically involves two parts. One part is the antenna itself, which converts the guided wave into a space wave, and the other part is its feeding network - the sum-difference network, also called a comparator, which provides the antenna with the required amplitude and phase. The sum-difference network is generally composed of a waveguide magic T, which has a three-dimensional spatial structure and is difficult to process. In order to reduce the difficulty of processing, the planar processing method is more commonly used in the high-frequency band. More specifically, the current mainstream uses four 3dB couplers plus four 90° phase shifters to form a planar sum-difference network, which has the characteristics of compactness and planarity, and is easy to process.

[0004] However, at present, most of the research on the 3dB180° coupler, the core component of the single pulse sum-difference network, is in the W band and below, and there are few reports on higher frequency bands (sub-terahertz bands). In the sub-terahertz band, there are still problems such as large amplitude and phase errors and large processing errors. Summary of the invention

[0005] In order to solve the problems existing in the above-mentioned prior art, the present invention provides a 90° phase shifter and a 3dB180° coupler for a terahertz communication tracking system, which solves the technical problems that the existing phase shifters cannot achieve phase shifting in the terahertz low frequency band and are not easy to integrate.

[0006] A 90° phase shifter for a terahertz communication tracking system comprises a waveguide, a first structure and a second structure, wherein the first structure comprises a first step recessed inwardly arranged at a narrow side of the waveguide, and the second structure comprises a second step protruding outwardly arranged at a wide side of the waveguide.

[0007] Preferably, the first steps are arranged in an up-and-down staggered manner, and the second steps are arranged in a gradually changing interval manner.

[0008] Preferably, the dispersion curves of the first structure and the second structure are parallel to each other. Specifically, the phase shift of the first structure and the second structure can be calculated by the formula φ=β×l, where φ is the phase shift, β is the structural propagation constant, and l is the structural length. The propagation constants of the first structure and the second structure are close to the frequency variation slope, that is, the dispersion curves are parallel. The relative phase difference of the broadband is achieved according to the relative phase difference formula Ψ=β1×l1-β2×l2, where β1 is the first structural propagation constant, β2 is the second structural propagation constant, l1 is the first structural length, and l2 is the second structural length.

[0009] Preferably, the first structure obtains an advanced phase amount relative to the waveguide, and the second structure obtains a lagging phase amount relative to the waveguide. Specifically, the first structure is located at the narrow side of the waveguide, has a greater impact on the magnetic field, is inductive, and obtains an advanced phase amount relative to the waveguide, and the second structure is located at the wide side of the waveguide, has a greater impact on the electric field, is capacitive, and obtains a lagging phase amount relative to the waveguide.

[0010] Preferably, the phase shift amount of the first structure increases with the increase of the height, width and number of the first steps (13), and the phase shift amount of the second structure increases with the increase of the height, width and number of the second steps (12).

[0011] Preferably, the relative phase difference between the first structure and the second structure is 90°.

[0012] A 3dB180° coupler for a terahertz communication tracking system comprises a 3dB90° coupler and the 90° phase shifter for a terahertz communication tracking system as claimed in any one of claims 1 to 5, wherein the first structure and the second structure are respectively arranged at the through end and the coupling end of the 3dB90° coupler.

[0013] Preferably, the 3dB 90° coupler uses the H-plane single-hole coupling theory, and the width of propagation at the coupling hole ranges from 1 wavelength to 1.5 wavelengths.

[0014] The beneficial effects of the present invention include:

[0015] 1. The 90° phase shifter designed in the present invention is easier to process, avoiding excessive pin phase shifting in traditional phase shifters, reducing processing errors, and making broadband phase shifting in the terahertz frequency band possible;

[0016] 2. The 3dB 180° coupler designed by the present invention adopts a 90° phase shifter and a new structure, which can produce low amplitude-phase error imbalance in the terahertz frequency band;

[0017] 3. The 3dB 180° coupler of the present invention is composed of a 3dB 90° coupler plus a 90° phase shifter, and has a planar structure, which is convenient for integration and miniaturization; BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a cross-sectional structural diagram of a 90° phase shifter according to the present invention.

[0019] Figure 2 It is a cross-sectional structural dimension diagram of the 90° phase shifter involved in the present invention.

[0020] Figure 3 It is a cross-sectional structural diagram of a 3dB 90° coupler according to the present invention.

[0021] Figure 4 It is a cross-sectional structural diagram of a 3dB 180° coupler according to the present invention.

[0022] Figure 5 It is a simulation diagram of S parameters of each port of the 3dB180° coupler used in the sum and difference network of the present invention.

[0023] Figure 6 It is a simulation diagram of the amplitude and phase error of the 3dB180° coupler used in the sum and difference network of the present invention.

[0024] Reference numerals

[0025] 11 - waveguide, 13 - first step, 12 - second step, 21 - first port, 22 - second port, 23 - third port, 24 - fourth port, 31 - port one, 32 - port two, 33 - port three, 34 - port four. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0027] The following is combined with Figure 1-6The specific embodiments of the present invention are described in detail;

[0028] A 90° phase shifter for terahertz communication tracking system, such as Figure 1 As shown, it includes a waveguide 11, a first structure and a second structure, as Figure 1 As shown in (b), the first structure includes a first step 13 which is recessed inwardly and is arranged on the narrow side of the waveguide 11. Figure 1 As shown in (a), the second structure includes a second step 12 protruding outward and arranged on the wide side of the waveguide 11.

[0029] The first steps 13 are arranged in an up-and-down staggered manner, and the second steps 12 are arranged in a gradually changing interval manner.

[0030] The first structure obtains an advanced phase amount relative to the waveguide, and the second structure obtains a lagging phase amount relative to the waveguide. Specifically, the first structure is located at the narrow side of the waveguide, has a greater impact on the magnetic field, is inductive, and obtains an advanced phase amount relative to the waveguide, and the second structure is located at the wide side of the waveguide, has a greater impact on the electric field, is capacitive, and obtains a lagging phase amount relative to the waveguide. In this embodiment, the relative phase difference between the first structure and the second structure is 90°.

[0031] The phase shift amount can be adjusted by adjusting the height and width of the first step 13, and can also be adjusted by adjusting the height and width of the second step 12; specifically, the phase shift amount of the first structure increases with the increase of the height, width and number of the first steps 13, and the phase shift amount of the second structure increases with the increase of the height, width and number of the second steps 12.

[0032] Specifically, the phase shift of the first structure and the second structure can be calculated by the formula φ=β×l, where φ is the phase shift, β is the structural propagation constant, and l is the structural length. The propagation constants of the first structure and the second structure are close to the frequency change slope, that is, the dispersion curves are parallel. According to the relative phase difference formula Ψ=β1×l1-β2×l2 between the two, a broadband relative phase difference is achieved, where β1 is the first structure propagation constant, β2 is the second structure propagation constant, l1 is the first structure length, and l2 is the second structure length.

[0033] The dispersion curves of the first structure and the second structure are parallel to each other, and can be combined to achieve a broadband phase shift of more than 20% relative to the bandwidth, and the bandwidth can be further increased by increasing the number of steps.

[0034] Specifically, Figure 2 As shown, the second step 12 is a groove with a gradually changing spacing on the wide side of the waveguide 11, which is used to complete the phase control, such as Figure 2As shown in (a), the groove depth E_w=0.15mm, the groove length E_l=1.06mm, and in order to reduce the echo of the structure, a gradual groove spacing g1=0.27mm, g2=0.41mm, g3=0.52mm is set; the first step 13 is an inward protrusion on the narrow side of the waveguide 11, which is used to compensate for the problem that the groove phase shift bandwidth is too narrow, as shown in FIG. Figure 2 As shown in (b), the specific dimensions of the protrusions are H_w=0.16mm, H_l=3.07mm. At the same time, in order to reduce the echo, the distance between the two protrusions is adjusted to g4=3.34mm, so that the structure has a smaller echo.

[0035] In another embodiment, a 3dB180° coupler for a terahertz communication tracking system is provided, comprising a 3dB90° coupler and the aforementioned 90° phase shifter, the entire structure forming a planar structure, which is convenient for processing; the first structure and the second structure are respectively arranged at the through end and the coupling end of the 3dB90° coupler, which can effectively adjust the port reflection and reduce the amplitude error of the two ports.

[0036] The 3dB90° coupler uses the H-plane single-hole coupling theory and controls the propagation width at the coupling hole to be between the wavelength of the TE10 mode waveguide 11 and the wavelength of the TE20 mode waveguide 11, thereby ensuring that the TE10 mode and the TE20 mode propagate simultaneously, and utilizing the characteristics of the TE10 mode and the TE20 mode being equal-amplitude and anti-phase to obtain equal-amplitude signals with a phase difference of 90°.

[0037] Specifically, Figure 3 As shown, the 3dB90° coupler is a short slot coupler, including a first port 21, a second port 22, a third port 23 and a fourth port 24. The parameters such as w and l can be adjusted (including the three-step widths of the waveguide side wall of the 3dB90° coupler are w1, w2, w3, and the lengths are l1, l2, l3, the width of the middle coupling hole w, and the length of the coupling hole l) to make the structure have a smaller amplitude and phase error in the 200-220GHz frequency band; wherein, when the signal is input from the first port 21, the second port 22 is a through port, the third port 23 is a coupling port, and the fourth port 24 is an isolation port. The structure and the attached Figure 1 Combination, specifically, the second port 22 is connected to the first structure, that is, the attached Figure 1 (b), the third port 23 is connected to the second structure, that is, Figure 1 (a), forming a 3dB 180° coupler. Figure 4 As shown, the 3dB 180° coupler includes port 1 31, port 2 32, port 33, and port 4 34. The signal from port 1 31 to port 2 32 and port 33 is an in-phase signal, and the signal from port 4 34 to port 2 32 and port 33 is an anti-phase signal.

[0038] Specifically, the specific simulation effect of the 3dB 180° coupler of the present invention is as follows: Figure 5 , Figure 6 As shown:

[0039] like Figure 5 As shown, the absolute value of S11 is the return loss, and the absolute value of S41 is the isolation. In the frequency range of 200-220GHz, S11 and S44 are better than -20dB, the return loss is greater than 20dB, S41 is better than -16dB, and the isolation is greater than 16dB. It has good return loss and isolation, which is about 20dB overall within the bandwidth.

[0040] like Figure 6 As shown, the 3dB 180° coupler port phase imbalance is ±1°, and the amplitude imbalance is ±0.2dB, which has a lower port amplitude and phase imbalance.

[0041] The above-mentioned embodiments only express the specific implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the protection scope of the present application. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the technical solution concept of the present application, and these all belong to the protection scope of the present application.

Claims

1. A 3dB 180° coupler for terahertz communication tracking system, characterized in that: The invention comprises a 3dB 90° coupler and a first structure and a second structure, wherein the first structure comprises a first step (13) which is recessed inwardly and is arranged on a narrow side of a waveguide (11), and the second structure comprises a second step (12) which is protruded outwardly and is arranged on a wide side of another waveguide; the first steps (13) are arranged in an up-and-down staggered manner, and the second steps (12) are arranged in a gradually changing pitch, and the first structure and the second structure are respectively arranged at a straight-through end and a coupling end of the 3dB 90° coupler.

2. The 3dB 180° coupler for a terahertz communication tracking system according to claim 1, characterized in that: The dispersion curves of the first structure and the second structure are parallel to each other.

3. The 3dB 180° coupler for a terahertz communication tracking system according to claim 1, characterized in that: The first structure obtains an advanced phase amount relative to the waveguide, and the second structure obtains a delayed phase amount relative to the waveguide.

4. The 3dB 180° coupler for a terahertz communication tracking system according to claim 1, characterized in that: The phase shift amount of the first structure increases with the increase of the height, width and number of the first steps (13), and the phase shift amount of the second structure increases with the increase of the height, width and number of the second steps (12).

5. The 3dB 180° coupler for a terahertz communication tracking system according to claim 1, characterized in that: The relative phase difference between the first structure and the second structure is 90°.

6. The 3dB 180° coupler for a terahertz communication tracking system according to claim 1, characterized in that: The 3dB 90° coupler uses the H-plane single-hole coupling theory, and the width of propagation at the coupling hole ranges from 1 wavelength to 1.5 wavelengths.

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