CN114899602A - 500GHz isolator for terahertz transmitting-receiving system - Google Patents
500GHz isolator for terahertz transmitting-receiving system Download PDFInfo
- Publication number
- CN114899602A CN114899602A CN202210541828.2A CN202210541828A CN114899602A CN 114899602 A CN114899602 A CN 114899602A CN 202210541828 A CN202210541828 A CN 202210541828A CN 114899602 A CN114899602 A CN 114899602A
- Authority
- CN
- China
- Prior art keywords
- port
- directional coupler
- isolator
- terahertz
- 500ghz
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/52—Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure
- H01Q1/521—Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure reducing the coupling between adjacent antennas
- H01Q1/525—Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure reducing the coupling between adjacent antennas between emitting and receiving antennas
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P5/00—Coupling devices of the waveguide type
- H01P5/12—Coupling devices having more than two ports
- H01P5/16—Conjugate devices, i.e. devices having at least one port decoupled from one other port
- H01P5/18—Conjugate devices, i.e. devices having at least one port decoupled from one other port consisting of two coupled guides, e.g. directional couplers
- H01P5/181—Conjugate devices, i.e. devices having at least one port decoupled from one other port consisting of two coupled guides, e.g. directional couplers the guides being hollow waveguides
Landscapes
- Optical Integrated Circuits (AREA)
Abstract
The invention discloses a 500GHz isolator for a terahertz transceiving system, wherein the terahertz transceiving system comprises a transmitting link, a receiving link and an antenna, the working frequency is 500GHz, and the isolator is a branched waveguide directional coupler and is used for realizing high isolation between the transmitting link and the receiving link of the terahertz transceiving system; the directional coupler comprises an input port (1), an isolation port (2), a through port (3), a coupling port (7) and 3 branch lines (6); the input port (1) is connected with a transmitting link, the isolation port (2) is connected with a receiving link, the through port (3) is connected with an antenna, and the coupling port (7) is filled with wave-absorbing materials or connected with a load to absorb electromagnetic energy in a matching way; the main and auxiliary waveguides of the directional coupler adopt standard waveguides WR 1.9. The terahertz transmission and receiving circuit is used in a terahertz transmission and receiving system, and the isolation between the transmission and receiving links is remarkably improved under the conditions of low volume, low cost and low system complexity.
Description
Technical Field
The invention belongs to the field of terahertz solid-state circuits, and particularly relates to a 500GHz isolator for a terahertz transceiving system.
Background
In a terahertz transceiving system, the isolation between a transmitting link and a receiving link is crucial, and the signal-to-noise ratio of a received echo signal is directly influenced, so that the sensitivity, the imaging effect and the like of the system are influenced. The method for improving the isolation between two links of the terahertz transceiving system at present comprises the following steps: dual antenna techniques, signal cancellation techniques, isolation using circulators or switches, etc.
In the above methods, although the former two methods have a certain effect on improving the isolation, they cause a series of problems such as an increase in system volume, an increase in cost, and an increase in system complexity. The scheme of realizing transmitting and receiving isolation by using a circulator or a switch is mostly concentrated below a Ku wave band, and the application in the terahertz frequency band is not mature. Aiming at the problems, the invention aims to explore the high isolation degree of the input port and the isolation port of the directional coupler and realize the isolation of the terahertz transceiving link.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a 500GHz isolator for a terahertz transceiving system.
In order to achieve the purpose, the invention provides a 500GHz isolator for a terahertz transceiving system, wherein the terahertz transceiving system comprises a transmitting link, a receiving link and an antenna, the working frequency is 500GHz, and the isolator is a branched waveguide directional coupler and is used for achieving high isolation between the transmitting link and the receiving link of the terahertz transceiving system; it is characterized in that the preparation method is characterized in that,
the directional coupler comprises an input port, an isolation port, a through port, a coupling port and 3 branch lines; the input port is connected with the transmitting link, the isolation port is connected with the receiving link, the direct port is connected with the antenna, and the coupling port is filled with wave-absorbing materials or connected with a load to match and absorb electromagnetic energy; and the main waveguide and the auxiliary waveguide of the directional coupler adopt standard waveguides WR 1.9.
As a modification of the above isolator, the 3 branch lines include a first branch line, a second branch line, and a third branch line, wherein,
a first branch line width of a, a second branch line width of b, a third branch line width of cThe distance between the branch line and the second branch line is W 1 The distance between the second branch line and the third branch line is W 2 (ii) a The following relationship is satisfied:
min(a,b,c,W 1 ,W 2 )≥80μm
wherein λ is g Representing the waveguide wavelength.
As an improvement of the above isolator, the main transmission line, the sub-transmission line, and the 3 branch lines of the directional coupler each use a rectangular waveguide.
As an improvement of the above isolator, the degree of coupling of the directional coupler is 3 dB.
As an improvement of the isolator, the cavity and the cover plate of the directional coupler are made of aluminum, aluminum alloy or copper.
As an improvement of the isolator, silver plating technology is adopted on the surfaces of the cavity and the cover plate of the directional coupler.
As an improvement of the isolator, the input port and the isolation port of the directional coupler are led out by bending the waveguide, and flanges are additionally arranged on the two ports.
Compared with the prior art, the invention has the advantages that:
1. the invention creatively provides that the directional coupler is applied to a 500GHz terahertz transceiving system, so that the isolation between transceiving links is improved;
2. the core device designed by the invention, namely the terahertz frequency band high-isolation directional coupler has the advantages of simple and small structure, easiness in processing, lower cost, good isolation and coupling degree and the like, and the isolation between the receiving and transmitting links can be obviously improved under the conditions of lower volume, cost and system complexity by applying the terahertz frequency band high-isolation directional coupler to a terahertz receiving and transmitting system with requirements on volume.
Drawings
FIG. 1 is a schematic diagram of a 500GHz isolator connection for a terahertz transceiving system of the present invention;
FIG. 2 is a schematic diagram of the core coupling region structure of the present invention;
FIG. 3 is a plan view of the core coupling region structure of the present invention;
fig. 4 shows the frequency characteristics of the reflection coefficient and the isolation of the directional coupler when the center frequency obtained by the measurement is 500GHz, that is, the S parameter obtained by the measurement using the vector network analyzer.
Reference numerals
1. Input port 2, isolation port 3, pass-through port
4. Main transmission line 5, auxiliary transmission line 6, branch line
7. Coupling port
Detailed Description
In a terahertz transceiving system, if the isolation between a transmitting link and a receiving link is insufficient, energy is leaked to an opposite link, and problems of sensitivity reduction, receiver saturation and the like are caused. In order to solve the problem, the invention provides a terahertz transceiving system high-isolation implementation method based on a directional coupler.
A directional coupler is a directional power-distributing four-port passive device commonly used in microwave solid-state circuits. Through the design of the coupling structure, energy can be offset at the isolated port due to the reverse superposition of phases, so that high isolation between the input port and the isolated port is realized.
The invention is based on the method of the branch line directional coupler, an input port is connected with a transmitting link of the system, an isolation port is connected with a receiving link of the system, a through port is connected with a feed source, an antenna and the like, and a coupling port is connected with wave-absorbing materials or loads to match and absorb electromagnetic energy.
Preferably, the main transmission line, the sub-transmission line, and the branch line of the coupler each use a rectangular waveguide.
Preferably, the number of the branched waveguides is two branches, three branches or four branches, so that the processing difficulty is reduced while the performance is ensured.
Preferably, the coupling of the coupler is selected to be around 3dB to ensure that the received signal has sufficient strength.
Preferably, the cavity and the cover plate are made of any one of aluminum, aluminum alloy or copper materials, silver can be selectively plated on the surfaces of the cavity and the cover plate, the cost is low, materials can be conveniently obtained, and the welding is convenient while the electrical conductivity is improved.
According to the invention, by designing a structure of the branch waveguide directional coupler and determining specific size parameters by taking the wavelength at the central frequency point of the directional coupler as a calculation basis, high isolation between a transmitting link and a receiving link in a terahertz transceiving system is realized.
The invention has the advantages that: simple structure, easy manufacture and excellent performance.
The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and examples.
Examples
As shown in fig. 1, an embodiment of the present invention provides a 500GHz isolator for a terahertz transceiving system, which is applied to the 500GHz transceiving system. The terahertz transmitting-receiving system comprises a transmitting link, a receiving link and an antenna, the working frequency is 500GHz, and the isolator is a branched waveguide directional coupler and is used for realizing high isolation between the transmitting link and the receiving link of the terahertz transmitting-receiving system;
the directional coupler comprises an input port 1, an isolation port 2, a through port 3, a coupling port 7 and 3 branch lines 6; the input port 1 is connected with a transmitting link, the isolation port 2 is connected with a receiving link, the through port 3 is connected with an antenna, and the coupling port 7 is filled with wave-absorbing materials or connected with a load to absorb electromagnetic energy in a matching manner.
The waveguide size is standard waveguide WR1.9, and the size is 0.483 × 0.241 mm. In consideration of the assembly problem of the device and other components of the system, the ports of the coupler are led out by bending the waveguide, UG-387 standard flanges are additionally arranged at the two ports, and the coupler is connected with other components of the system through the flanges.
As shown in FIG. 2, the three-branch structure is selected in this embodiment, the thinnest part of the diaphragm is 100 μm (corresponding to a, b, c marked in FIG. 3), and the thinnest part of the cavity is 80 μm (corresponding to W marked in FIG. 3) 1 ,W 2 ) And the CNC process with relatively mature and low cost can be used for finishing the processing. The isolation at the operating center frequency of 520GHz is-43 dB and possesses a high isolation bandwidth of better than-30 dB at about 10 GHz. The result shows that the terahertz wave transmitting and receiving system can obviously improve the link isolation in the terahertz wave transmitting and receiving system, is simple in structure and convenient to process, and has wide application prospect.
As shown in fig. 3, the 3 branch lines include a first branch line, a second branch line and a third branch line, and the principle is as follows:
the width of the first branch line is a, the width of the second branch line is b, the width of the third branch line is c, and the distance between the first branch line and the second branch line is W 1 The distance between the second branch line and the third branch line is W 2 (ii) a The following relationship is satisfied:
min(a,b,c,W 1 ,W 2 )≥80μm
wherein λ is g Representing the waveguide wavelength.
The directional coupler is a first, a second, a third and a fourth port respectively in a clockwise direction from the input port. The size initial value of each branch line can be calculated by using an odd-even mode analysis method, and the specific principle is as follows: inputting the first port and the fourth port by continuous excitation in the same direction and with equal amplitude (both 1/2), wherein the current on the symmetrical plane of the branch line is 0 at the moment, which can be regarded as an open circuit, and the condition is called even mode excitation; the excitation input ports, namely the first port and the fourth port, are continuous, reverse and equal in amplitude (1/2), and the voltage on the symmetrical plane of the branch line is 0 at the moment, which can be regarded as short circuit, and the condition is called oddAnd (4) exciting the mode. The odd-even modes are superposed, namely the first port has excitation with the amplitude of 1, and the fourth port has no signal input. Suppose that the transmission coefficients of the even and odd modes are T e And T o The reflection coefficients are respectively gamma e And Γ o Then the output of each port can be expressed as follows:
at this time, the four-port network may be equivalently analyzed for the two-port network, and the transmission coefficient and the reflection coefficient are calculated by using the ABCD matrix, and the specific relationship is as follows:
wherein Γ and T are respectively S of the two-port network 11 And S 12 。
Take a three-branch directional coupler as an example. Assuming that the width of the branch line at the center is n, the widths of the branch lines at the left and right sides are m, and the distance between the centers of the branch lines and the length of the branch lines are 1/4 of the working wavelength, the network even mode matrix is as follows:
wherein the 1 st, 3 rd and 5 th matrixes are transmission matrixes of an eighth-wavelength open line, and the 2 nd and 4 th matrixes are transmission matrixes of a quarter-wavelength transmission line. Only m in the above formula needs to be replaced by m, namely the odd-mode matrix of the network:
for reason ofFor a desired 3dB directional coupler, no reflections should be present in the odd and even modes, i.e.
Is 0, i.e. B ═ C, there are two possible values for m for a given n. To reduce the junction effect, the values are usually smaller, namely:
in addition, the output amplitudes of the second and third ports should be equal, i.e. | S 21 |＝|S 31 And if the values are combined, the ideal values of m and n are obtained. The initial value of the size of each branch line can be obtained by bringing the central frequency into 520GHz, and the performance requirements can be met by comprehensively considering optimization and adjustment such as performance, processing difficulty and the like.
The network even mode matrix is popularized to a waveguide directional coupler with k +2 branches, the widths of branch lines on the left side and the right side are set to be m, the widths of the rest branch lines are set to be n, and the center distance and the branch line length of each branch line are 1/4 of working wavelength, so that the network even mode matrix is as follows:
wherein S k (-n) is a chebyshev polynomial for n, as follows:
S 0 (-n)＝1
S 1 (-n)＝-n
S 2 (-n)＝n 2 -1
……
S k (-n)＝-nS k-1 (-n)-S k-2 (-n)
when S is k (x) In x ∈ [0,2 ]]And k is an integer between 2 and 12, the formula is satisfied, so that the initial value of the width of each branch waveguide of the multi-branch waveguide directional coupler can be obtained. Accordingly, the following design is obtained:
the main waveguide and the auxiliary waveguide are standard waveguides WR1.9, and the WR1.9 working frequency range is 400-600 GHz. The 80 μm arrangement is to ensure that the thinnest point cannot be too thin, otherwise the device is easily deformed and difficult to process.
As shown in fig. 3, a preferred embodiment, the size is 0.483 × 0.241 mm; the number of the branch lines is determined to be 3, the length of the branch lines is 200 μm, and the widths of the three branch lines are 80 μm, 100 μm and 85 μm in sequence; the distances between adjacent branches were 100 μm and 110 μm, respectively, with the dimensional parameters of the respective portions as follows:
TABLE 1 dimensional parameters
Fig. 4 shows the frequency characteristics of the reflection coefficient and the isolation of the directional coupler when the center frequency obtained by the measurement is 500GHz, that is, the S parameter obtained by the measurement using the vector network analyzer.
The method provided by the invention can be theoretically applied to the isolation requirement of terahertz transceiving systems with any frequency. In different application scenes, parameters such as waveguide size, branch line number, branch line size and the like are only required to be changed according to requirements such as central frequency, bandwidth, processing difficulty and the like.
The innovation points are as follows:
the method for improving the isolation between the transmitting and receiving links of the terahertz transmitting and receiving system by applying the directional coupler to the terahertz transmitting and receiving system is provided; and the design of the 500GHz branch waveguide directional coupler is completed.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and are not limited. Although the present invention has been described in detail with reference to the embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (7)
1. A500 GHz isolator for a terahertz transceiving system comprises a transmitting link, a receiving link and an antenna, wherein the working frequency is 500GHz, and the isolator is a branched waveguide directional coupler and is used for realizing high isolation between the transmitting link and the receiving link of the terahertz transceiving system; it is characterized in that the preparation method is characterized in that,
the branch waveguide directional coupler comprises an input port (1), an isolation port (2), a through port (3), a coupling port (7) and 3 branch lines (6); the input port (1) is connected with a transmitting link, the isolation port (2) is connected with a receiving link, the through port (3) is connected with an antenna, and the coupling port (7) is filled with wave-absorbing materials or connected with a load to absorb electromagnetic energy in a matching manner; and the main waveguide and the auxiliary waveguide of the branched waveguide directional coupler adopt standard waveguides WR 1.9.
2. The 500GHz isolator for a terahertz transceiving system according to claim 1, wherein the 3 branch lines (6) comprise a first branch line, a second branch line and a third branch line, wherein,
the width of the first branch line is a, the width of the second branch line is b, the width of the third branch line is c, and the distance between the first branch line and the second branch line is W 1 The distance between the second branch line and the third branch line is W 2 (ii) a The following relationship is satisfied:
min(a,b,c,W 1 ,W 2 )≥80μm
wherein λ is g Representing the waveguide wavelength.
3. The 500GHz isolator for terahertz transceiving system according to claim 2, wherein the main transmission line (4), the auxiliary transmission line (5) and the 3 branch lines (6) of the branch waveguide directional coupler all use rectangular waveguides.
4. The 500GHz isolator for terahertz transceiving system according to claim 1, wherein the degree of coupling of the branch waveguide directional coupler is 3 dB.
5. The 500GHz isolator for the terahertz transceiver system of claim 1, wherein the cavity and the cover plate of the branched waveguide directional coupler are made of aluminum, aluminum alloy or copper.
6. The 500GHz isolator for the terahertz transceiver system of claim 1, wherein the cavity and the cover plate surface of the branch waveguide directional coupler adopt a silver plating process.
7. The 500GHz isolator for the terahertz transceiver system as claimed in claim 1, wherein the input port (1) and the isolation port (2) of the branched waveguide directional coupler are led out through a bent waveguide, and flanges are additionally arranged at the two ports.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210541828.2A CN114899602A (en) | 2022-05-18 | 2022-05-18 | 500GHz isolator for terahertz transmitting-receiving system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210541828.2A CN114899602A (en) | 2022-05-18 | 2022-05-18 | 500GHz isolator for terahertz transmitting-receiving system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114899602A true CN114899602A (en) | 2022-08-12 |
Family
ID=82723174
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210541828.2A Pending CN114899602A (en) | 2022-05-18 | 2022-05-18 | 500GHz isolator for terahertz transmitting-receiving system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114899602A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117096568A (en) * | 2023-10-19 | 2023-11-21 | 电子科技大学 | Arch three-branch waveguide directional coupler |
-
2022
- 2022-05-18 CN CN202210541828.2A patent/CN114899602A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117096568A (en) * | 2023-10-19 | 2023-11-21 | 电子科技大学 | Arch three-branch waveguide directional coupler |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US7821355B2 (en) | Waveguide antenna front end | |
| US8816930B2 (en) | Waveguide orthomode transducer | |
| Gruszczynski et al. | Design of compensated coupled-stripline 3-dB directional couplers, phase shifters, and magic-T's—Part I: Single-section coupled-line circuits | |
| CN112909471B (en) | High-isolation rectangular waveguide-microstrip power divider | |
| CN104393390A (en) | Compact plane branch coupler for single-pass or double-pass band | |
| CN105826643A (en) | Half-mode substrate integrated waveguide-based compact six-port circuit | |
| EP2360776B1 (en) | Microwave directional coupler | |
| CN111786068B (en) | Broadband directional coupler with harmonic suppression function | |
| CN111952706A (en) | Compact waveguide hybrid synthesis network | |
| US10050324B2 (en) | Wide band radio frequency circulator | |
| CN114899602A (en) | 500GHz isolator for terahertz transmitting-receiving system | |
| CN113258244B (en) | Rectangular waveguide microstrip 0-degree-phase-difference high-isolation broadband power divider | |
| CN115473025B (en) | Waveguide difference port magic T based on microstrip-waveguide hybrid integration | |
| CN210805976U (en) | Miniaturized broadband four-way out-phase power divider based on Marchand branch balun | |
| CN109585994B (en) | Miniature double-layer half-mode substrate integrated waveguide six-port device | |
| EP2345099A1 (en) | A waveguide antenna front end | |
| CN105244573A (en) | Dual-mode high-performance balance band-pass filter based on E-shaped resonators | |
| CN108879098B (en) | Microstrip line 2 x 4butler matrix with band-pass filtering characteristic | |
| Li et al. | Design of a ku-band orthomode transducer | |
| CN106684517B (en) | Novel broadband 3dB 90-degree electric bridge | |
| CN112510337B (en) | Cross coupler based on mode synthesis, construction method and impedance matching structure | |
| CN109390650B (en) | Miniaturized double-layer substrate integrated waveguide six-port device | |
| CN113708026B (en) | Differential 90-degree Scheffman phase shifter based on slot line | |
| CN111326834B (en) | Symmetric double-arm rectangular-circular waveguide mode converter | |
| Gurulakshmi et al. | Numerical analysis on slinky 3 dB power divider for high speed RF sensor system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |