CN114124243B

CN114124243B - High-isolation terahertz orthogonal mode isolation duplexer easy to machine

Info

Publication number: CN114124243B
Application number: CN202210097720.9A
Authority: CN
Inventors: 张波; 牛中乾; 杨晓波; 樊勇; 管明; 胡怡; 张季聪; 杨晓帆; 刘轲; 陈智
Original assignee: University of Electronic Science and Technology of China
Current assignee: University of Electronic Science and Technology of China
Priority date: 2022-01-27
Filing date: 2022-01-27
Publication date: 2022-05-03
Anticipated expiration: 2042-01-27
Also published as: CN114124243A

Abstract

The invention provides an easy-to-process high-isolation terahertz orthogonal mode isolation duplexer, and belongs to the technical field of duplexer devices. The invention innovatively provides that the orthogonal mode coupler is introduced into the duplexer, so that the problem that the existing frequency division duplexer has to use different frequency band signal resources is solved, and the application scene of the duplexer is enlarged; meanwhile, the E-plane 90-degree twisted waveguide is connected with one output port of the orthogonal mode coupler, so that the two output ports of the duplexer have the same mode, the limitation that the 90-degree reverse cascade circuit is needed when the output port is not connected with the twisted waveguide after the orthogonal mode coupler is directly introduced into the duplexer is avoided, and meanwhile, the E-plane 90-degree twisted waveguide can be processed by utilizing a traditional E-plane subdivision structure, so that the twisted waveguide is convenient to prepare, and the large-scale application of the duplexer is easy to realize.

Description

High-isolation terahertz orthogonal mode isolation duplexer easy to machine

Technical Field

The invention belongs to the technical field of duplexer devices, and particularly relates to a high-isolation terahertz orthogonal mode isolation duplexer easy to process.

Background

At present, a common antenna for transmitting and receiving is basically adopted in a radio frequency transmitting front-end link, and the use of a duplexer is necessarily involved in the process. At present, duplexers are mainly divided into two types according to the working types: 1) time division duplexers, i.e. transmission and reception, are separated in time and do not conflict with each other; however, such duplexers have great limitations in practical life scene applications; 2) the frequency division duplexer mainly has different working frequency bands of the transceiving links, so that transceiving can work simultaneously, and only different frequency bands are selected. But as the use of communication frequency resources saturates, the use of frequency division duplexers is also diminishing.

It is known that the direction of the electric field of a radio wave changes according to a certain rule when the radio wave propagates in space, and this phenomenon is called the polarization of the radio wave. In general, the polarization direction of a radio wave depends on the direction of its electric field vector E, and thus the electric field direction of an electromagnetic wave is called its polarization direction. If the direction of the electric field of the electromagnetic wave is vertical to the ground plane, the electromagnetic wave is called as a vertical polarized wave; if the direction of the electric field vector E is parallel to the ground plane, it is called a horizontally polarized wave. An orthogonal mode coupler, also called an orthogonal mode converter, is a common structure capable of realizing a mode isolation circuit in a terahertz wave band, has the advantages of port matching, high isolation degree, small insertion loss and the like, improves the defects of the traditional coupler, and is based on mode orthogonality, two communication channels in the orthogonal mode coupler can transmit mutually isolated and mutually orthogonal signals under the same frequency, so that the orthogonal mode coupler is widely applied to polarization multiplexing in a large-capacity communication system to realize double-frequency resources.

Terahertz waves are just between the microscopic quantum theory and the macroscopic classical theory. Due to the special position of the terahertz wave, the terahertz wave can show a plurality of unique characteristics different from other types of electromagnetic radiation, and the characteristics determine that the terahertz wave has wide and good application prospects in a plurality of fields. But in the terahertz frequency band, the circuit size is sharply reduced, which causes the duplexer to be difficult to process. Meanwhile, two output ports of the conventional terahertz frequency band orthogonal mode coupler are orthogonal, so that after two paths of signals are output, a connected circuit needs to be inverted by 90 degrees, the difficulty of multi-circuit cascade is greatly increased, and even the circuit cannot be connected.

Therefore, how to design the terahertz frequency band orthogonal mode isolation duplexer which is easy to process in the terahertz frequency band becomes a problem to be solved urgently.

Disclosure of Invention

Aiming at the problems in the background art, the invention aims to provide a high-isolation terahertz orthogonal mode isolation duplexer which is easy to process. The duplexer of the invention constructs the E-plane 90-degree twisted waveguide based on the advantage of frequency multiplexing of the orthogonal mode coupler, and the E-plane 90-degree twisted waveguide is connected with one port of the orthogonal mode coupler, so that the signal transmission modes of two output ports of the duplexer are ensured to be orthogonal to each other, a cascade circuit does not need to be inverted by 90 degrees, and the difficulty of circuit cascade is reduced; meanwhile, the whole device can be processed by utilizing the E-surface subdivision structure.

In order to achieve the purpose, the technical scheme of the invention is as follows:

an easy-to-process high-isolation terahertz orthogonal mode isolation duplexer comprises an orthogonal mode coupler, an E-plane 90-degree twisted waveguide and a cavity filter;

the orthogonal mode coupler is provided with three ports, and comprises an input port and two output ports, wherein the modes of the electromagnetic waves transmitted in the two output ports are orthogonal to each other; one end of the E-plane 90-degree twisted waveguide is connected with one of the output ports, so that the mode of the electromagnetic wave passing through the E-plane 90-degree twisted waveguide is the same as that of the electromagnetic wave in the other output port; the other end of the E-plane 90-degree twisted waveguide and the other output port of the orthogonal mode coupler are uniformly connected with a cavity filter; the other ends of the two cavity filters are connected with a rectangular waveguide which is used as an output port of the isolation duplexer.

Further, the E-plane 90 ° twisted waveguide is composed of an input waveguide, a double square transition structure and an output waveguide, wherein the input waveguide and the output waveguide are both rectangular waveguides, and the double square transition structure is composed of two identical square waveguides partially overlapped and is used for rotating the vertical polarization in the H-plane waveguide by 45 ° and then converting the 45 ° polarized wave into the horizontal polarization in the E-plane waveguide.

Furthermore, one of the E-plane 90-degree twisted waveguide input waveguide and the output waveguide is a vertically polarized waveguide, the other one of the E-plane 90-degree twisted waveguide input waveguide and the output waveguide is a horizontally polarized waveguide, and the rectangular cross sections of the two waveguides are the same in size.

Further, the E-plane 90 DEG twisted waveguide and the orthogonal mode coupler are connected in the same electromagnetic wave polarization mode.

Further, the cavity filter is a high rectangular coefficient filter.

Further, the filter coefficients of the high rectangular coefficient filter should be greater than 65%.

In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:

1. the invention innovatively provides that the orthogonal mode coupler is introduced into the duplexer, so that the problem that the conventional frequency division duplexer has to use different frequency band signal resources is solved, and the application scene of the duplexer is enlarged; meanwhile, the E-plane 90-degree twisted waveguide is connected with one output port of the orthogonal mode coupler, so that the two output ports of the duplexer have the same mode, the limitation that the 90-degree reverse cascade circuit is needed when the output port is not connected with the twisted waveguide after the orthogonal mode coupler is directly introduced into the duplexer is avoided, and meanwhile, the E-plane 90-degree twisted waveguide can be processed by utilizing a traditional E-plane subdivision structure, so that the twisted waveguide is convenient to prepare, and the large-scale application of the duplexer is easy to realize.

2. The duplexer integrates high rectangular coefficient filters at two output ports, further inhibits useless sideband signals in space and improves duplex performance; while having a high degree of isolation.

Drawings

Fig. 1 is a circuit configuration diagram of the isolation duplexer of the present invention.

Fig. 2 is a schematic view of the overall structure of the E-plane 90 ° twisted waveguide according to the present invention.

Fig. 3 is a schematic diagram of a double square transition structure in an E-plane 90 ° twisted waveguide according to the present invention.

Fig. 4 is an electrical schematic diagram of an orthomode coupler.

Fig. 5 is a diagram showing simulation results of S-parameters of the isolation duplexer of the present invention.

Fig. 6 is a diagram showing the simulation result of the S-polarization isolation of the isolation duplexer of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the following embodiments and accompanying drawings.

A circuit structure diagram of an easy-to-process high-isolation terahertz mode isolation duplexer is shown in figure 1 and comprises an orthogonal mode coupler 1, an E-plane 90-degree twisted waveguide 4, a first cavity filter 5 and a second cavity filter 6; the orthogonal mode coupler 1 is provided with two output ports, the first output port is a vertical mode output port 2, the second output port is a horizontal mode output port 3, a horizontal polarization waveguide of an E-plane 90-degree twisted waveguide 4 is connected with the horizontal mode output port 3 of the orthogonal mode coupler, a first cavity filter 5 is connected with the vertical mode output port 2 of the orthogonal mode coupler, and a second cavity filter 6 is connected with the vertical polarization waveguide of the E-plane 90-degree twisted waveguide 4; the other end of the first cavity filter 5 is connected with a rectangular waveguide to serve as a first vertical output port 7 of the isolation duplexer, and the other end of the second cavity filter 6 is connected with a rectangular waveguide to serve as a second vertical output port 8 of the isolation duplexer.

The overall structural schematic diagram of the E-plane 90 ° twisted waveguide 4 is shown in fig. 2, and as can be seen from fig. 2, the E-plane 90 ° twisted waveguide is composed of an input waveguide, a double square transition structure and an output waveguide, wherein the input waveguide and the output waveguide are both rectangular waveguides, one of the input waveguide and the output waveguide is a vertically polarized waveguide, the other is a horizontally polarized waveguide, and the rectangular cross-sectional dimensions of the two waveguides are the same; meanwhile, the polarization mode of the electromagnetic wave at the joint of the E-plane 90-degree twisted waveguide and the orthogonal mode coupler is the same. Fig. 3 is a schematic diagram of a double square transition structure in an E-plane 90-degree twisted waveguide, where the double square transition structure is composed of an upper square waveguide and a lower square waveguide which are partially overlapped with each other, and is used to rotate the vertical polarization in the H-plane waveguide by 45 degrees, and then convert the 45-degree polarized wave into the horizontal polarization in the E-plane waveguide. At the same time, the edges of the square waveguide are chamfered, the purpose of which is for impedance matching. The input and output waveguide is selected as a waveguide WR4.3, the length a of the long side is 1.092mm, the length b of the short side is 0.546mm,

the transmission frequency of the whole circuit is 170GHz to 260 GHz. A signal enters from an input port of the terahertz orthogonal mode coupler 1, and is divided into two parts to be transmitted to a vertical mode output port 2 and a horizontal mode output port 3, and the two ports are vertical to each other; the horizontal mode output port 3 is connected with the horizontal polarization waveguide of the E-plane 90-degree twisted waveguide 4, and the signal is changed into vertical polarization wave after passing through the E-plane 90-degree twisted waveguide 4 and is output from the second vertical output port 8.

Fig. 4 is an electrical schematic diagram of an orthomode coupler. The orthomode coupler has three physical ports in structural view, but in electrical view, the common port directly connected to the feed horn is generally a circular waveguide port or a square waveguide port, which provides an electrical port for each of two mutually orthogonal polarized waves, i.e. TE₁₀Die or TE₀₁The mode, and therefore the quadrature mode coupler, is a four port device in electrical form. Electrical portaAnd an electrical portbEach mode signal is independently transmitted, and is generally formed by combining standard rectangular waveguide ports or coaxial ports. The function of the orthogonal mode coupler is to realize the mutual separation and synthesis of two orthogonal polarization signals and meet certain isolation requirements.

The isolation duplexer is modeled and simulated by using HFSS software, wherein fig. 5 is a simulation result diagram of S parameters of the isolation duplexer, and fig. 6 is a polarization isolation curve diagram of the isolation duplexer. As can be seen from a simulation result diagram, the return loss of each port of the coupler is better than-17.8 dB (the return loss of the two ports and the three ports are S11, S22 and S33 respectively) in the frequency band of 180-220 GHz, the isolation of the two modes is better than 50dB, and the performance is good.

While the invention has been described with reference to specific embodiments, any feature disclosed in this specification may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise; all of the disclosed features, or all of the method or process steps, may be combined in any combination, except mutually exclusive features and/or steps.

Claims

1. An easy-to-process high-isolation terahertz orthogonal mode isolation duplexer is characterized by comprising an orthogonal mode coupler, an E-plane 90-degree twisted waveguide and a cavity filter;

the orthogonal mode coupler is provided with three ports, and comprises an input port and two output ports, the modes of electromagnetic waves transmitted in the two output ports are orthogonal to each other, the input port of the orthogonal mode coupler is a rectangular waveguide, and the coupling of two signal transmission modes is realized in the rectangular waveguide; one end of the E-plane 90-degree twisted waveguide is connected with one of the output ports, so that the mode of the electromagnetic wave passing through the E-plane 90-degree twisted waveguide is the same as that of the electromagnetic wave in the other output port; the other end of the E-plane 90-degree twisted waveguide and the other output port of the orthogonal mode coupler are uniformly connected with a cavity filter; the other ends of the two cavity filters are connected with a rectangular waveguide which is used as an output port of the isolation duplexer; the isolation duplexer can be processed by utilizing an E-surface subdivision structure.

2. The high-isolation terahertz orthogonal mode isolation duplexer of claim 1, wherein the E-plane 90 ° twisted waveguide is composed of an input waveguide, a double square transition structure and an output waveguide, wherein the input waveguide and the output waveguide are both rectangular waveguides, and the double square transition structure is composed of two identical square waveguides partially overlapped and used for rotating vertical polarization in the H-plane waveguide by 45 ° and then converting the 45 ° polarized wave into horizontal polarization in the E-plane waveguide.

3. The high-isolation terahertz orthogonal mode isolation duplexer according to claim 2, wherein one of the E-plane 90-degree twisted waveguide input waveguide and the output waveguide is a vertically polarized waveguide, the other one of the E-plane 90-degree twisted waveguide input waveguide and the output waveguide is a horizontally polarized waveguide, and the rectangular cross sections of the two waveguides have the same size.

4. The high-isolation terahertz orthogonal mode isolation duplexer of claim 1, wherein the polarization mode of the electromagnetic wave at the connection of the E-plane 90 ° twisted waveguide and the orthogonal mode coupler is the same.

5. The high-isolation terahertz quadrature mode isolation duplexer of claim 1, wherein the cavity filter is a high rectangular coefficient filter.

6. The high-isolation terahertz quadrature mode isolation duplexer of claim 5, wherein the filter coefficients of the high-rectangular coefficient filter should be greater than 65%.