CN112350042B - Single-ended to differential magic T with filtering characteristics - Google Patents
Single-ended to differential magic T with filtering characteristics Download PDFInfo
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Abstract
The invention discloses a single-ended to differential magic T with a filtering characteristic, which solves the problems of poor frequency band selectivity, single port form and inconvenience in processing and integration of the conventional magic T. The invention is characterized in that a single-end to differential reverse-phase and in-phase power distribution network is arranged on the upper surface of a dielectric substrate, a pair of mutually symmetrical filter coupling output networks is arranged in the power distribution network, and the two networks are integrally connected through various types of microstrip-to-slot conversion structures. The filter coupling output network of the invention inserts and couples the branch loading type resonator through the L-shaped microstrip line and the L-shaped slot line structure. The invention improves the frequency band selectivity, effectively improves the space utilization rate and the integration level by increasing the transmission zero point, reduces the design complexity by introducing the single end to the differential port, has the advantages of low introduced noise and strong anti-interference capability, and is used as a novel radio frequency microwave device applied to a wireless communication system.
Description
Technical Field
The invention belongs to the technical field of microwave and radio frequency, and further relates to a radio frequency microwave device in the microwave and radio frequency field, in particular to a magic T with filtering characteristic from single end to difference, which is applied to a radio frequency front end of a wireless communication system.
Background
In recent years, with the rapid development of wireless communication systems, differential circuits have gained more and more attention and applications due to their excellent environmental noise and electromagnetic interference resistance. The power divider is one of the microwave devices essential in wireless systems, and its input port is often single-ended, but the devices connected to it are usually differential, such as differential mixer, differential oscillator, and differential antenna array. Therefore, to convert a single-ended signal to a differential signal and evenly distribute the power, a single-ended to differential power divider is typically required. Compared to other types of power splitters, such as differential-to-differential and differential-to-single-ended power splitters, the single-ended-to-differential power splitter type is undoubtedly one of the most widely used types. According to the output phase of the output port of the power divider, the power divider can be divided into an in-phase power divider with an output phase difference of 0 ° and a reverse-phase power divider with an output phase difference of 180 °, and the two power dividers with different output phases have respective advantages in a wireless communication system. In order to comply with the development trend of miniaturization and integration of a communication system, the magic T combines the functions of the in-phase power divider and the anti-phase power divider into a whole and supports in-phase and anti-phase transmission of output signals. Meanwhile, isolation is provided between input ports and output ports, and compared with a traditional power divider which needs to introduce isolation resistance to improve isolation, the method provides a new method for realizing high-isolation power division. Therefore, the magic T is concerned by a plurality of scholars at home and abroad more and more, and the magic T for researching the single-ended to differential magic T has wide application value.
For example, the Peng Li et al, in its published article, "SIW magic-T with bandpass response" (ELECTRONICS LETTERS, Vol.51, No.14, July, 2015), proposed a filter magic T based on substrate integrated waveguide technology. The in-phase and anti-phase power splitting functions and the filtering function can be implemented simultaneously on such a magic T. However, the design has no obvious transmission zero point on two sides of the filter passband, the frequency band selectivity is poor, and the structure is a traditional single-ended-to-single-ended structure, does not have a differential output function, and therefore has room for improvement.
For example, a differential-to-single-ended magic T based ON a Cavity structure is designed in a journal document "Cavity filtering map-T AND its integration into one band-to-one band power divider AND doubling power divider" published by students such as Jing-Yu Lin AND the like in IEEE transport ON MICROWAVE AND tech noise, AND can realize the functions of suppressing common-mode signals AND filtering differential-mode signals. However, the design still has the disadvantage of poor band selectivity, and the structure is a differential-to-single-ended structure, the application scenarios are limited, and in addition, the cavity structure is not favorable for processing and system integration.
In summary, the existing magic T design scheme has the disadvantages of poor frequency band selectivity, single port form, limited application scenarios and being not conducive to processing and system integration.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a single-ended to differential magic T with filtering characteristics, which has high integration level, good frequency band selectivity and easy processing.
The invention relates to a magic T with filtering characteristic from single end to difference, wherein a micro-strip structure is etched on the upper surface of a dielectric substrate, a metal grounding plate is integrally arranged on the lower surface of the dielectric substrate, a gap structure is etched on the metal grounding plate, the longitudinal center line of the dielectric substrate is the integral symmetry axis of the micro-strip structure and the gap structure, and the openings of U-shaped output micro-strip feeders at two ends of the micro-strip structure in the horizontal direction are outward; the microstrip structure comprises a single-ended to differential reverse phase power distribution network formed by a single-ended J-shaped input microstrip feeder line and a pair of differential U-shaped output microstrip feeder lines, and an in-phase power distribution network formed by a single-ended T-shaped input microstrip feeder line and a pair of differential U-shaped output microstrip feeder lines; the microstrip structures are symmetrical about a vertical axis AA' except for a J-shaped input microstrip feed line positioned at the upper end of the dielectric substrate; the slit line structure on the metal grounding plate is symmetrical about a vertical axis AA'; a pair of z output networks symmetrical about a vertical axis AA' exists in a single-ended to differential power distribution network, a first L-shaped stepped impedance microstrip line and a second L-shaped stepped impedance microstrip line in a microstrip structure in the filter coupling output network are symmetrically arranged to form a space capable of being inserted into a resonator, a stub loading type resonator is positioned below the space, a first L-shaped stepped impedance slot line and a second L-shaped stepped impedance slot line in a slot structure are arranged above a projection space of the space capable of being inserted into the resonator on a metal grounding plate, and the whole filter coupling output network is symmetrical about a main stub center line of the stub loading type resonator; the tail ends of the two branches of the T-shaped input microstrip feeder line are respectively provided with two metallized through holes, and the T-shaped input microstrip feeder line is connected with the lower metal grounding plate; and the coupling end of the J-shaped input micro-strip feeder line is provided with a metalized through hole for connecting the J-shaped input micro-strip feeder line with the lower metal grounding plate.
The invention solves the technical problems of poor magic T frequency band selectivity, single port form and inconvenience for processing and integration in the prior art.
Compared with the prior art, the invention has the following advantages:
first, the single-ended to differential magic T with filtering characteristics of the present invention employs various forms of coupling structures, achieving a compact structure and superior effects. Coupling an L-shaped stepped impedance microstrip line with a quarter-wavelength equivalent short-circuit branch on the upper surface with an L-shaped stepped impedance slot line with a quarter-wavelength equivalent open-circuit branch on the lower surface; coupling the U-shaped differential input microstrip line and the circular slot line; the coupling of the tail end of the short circuit T-shaped input microstrip feeder line branch with the metal through hole and the T-shaped slot line is used for realizing the energy transfer between the microstrip line and the slot line and realizing the miniaturization of the magic T. Meanwhile, the first L-shaped stepped impedance slot line and the second L-shaped stepped impedance slot line are adjacent in position, so that when signals are transmitted, a coupling effect between a source and a load can be generated, the transmission path of the signals is increased, a new transmission zero point is introduced to the right side of the differential mode passband, and the out-of-band rejection capability and the frequency selectivity of the differential mode signals are improved.
Second, the magic T of the present invention takes the form of a single-ended to differential port, which can convert a single-ended signal input from a conventional circuit into a differential signal connectable to a differencing device and provide a power-divided differential signal in two phase output relationships. The traditional magic T only can carry out a working mode of transmitting a single-ended signal to a single-ended signal, a plurality of balun devices are usually needed to be connected with a differential antenna, a differential passive device and a differential active device, and the single-ended to differential magic T realizes common-mode rejection of 200% of relative bandwidth by introducing a microstrip line to slot line conversion structure through the integrated design of a U-shaped differential output port.
Third, the present invention implements a single-ended to differential magic T with filtering characteristics. The device utilizes the power distribution and phase regulation and control capabilities of a T-shaped slot line structure and a T-shaped microstrip line structure to signals, introduces a branch loading type resonator based on a microstrip line-to-slot line conversion technology on the basis of realizing the traditional function of the magic T, greatly improves the filtering performance of the magic T, and greatly reduces the processing cost due to the single-layer structure of the magic T. In the field of the existing magic T device, all functions reach superior indexes, and the magic T device can be applied to a high-performance communication system.
Drawings
FIG. 1 is a schematic view of the overall structure of the present invention;
FIG. 2 is a top view of FIG. 1;
FIG. 3 is a schematic diagram illustrating position and dimension marks of structures on the upper surface of a dielectric substrate according to the present invention;
FIG. 4 is a schematic diagram illustrating position and dimension marks of structures on a lower surface of a dielectric substrate according to the present invention;
FIG. 5 is a simulation and actual map of the S parameters of the reverse phase power distribution moveout mode return loss and the moveout mode insertion loss of the present invention;
FIG. 6 is a simulation and actual map of the S parameters of the in-phase power distribution moveout mode return loss and the moveout mode insertion loss of the present invention;
FIG. 7 is an S-parameter simulation and actual map of isolation of the present invention.
FIG. 8 is a phase-consistent S-parameter simulation and empirical diagram of the present invention.
Detailed Description
The invention is described in detail below with reference to the figures and examples.
Example 1
The magic T is an essential important device in the modern communication field, combines the functions of the in-phase power divider and the anti-phase power divider into a whole, supports in-phase and anti-phase transmission of output signals, and provides flexible phase selection for a system. With the continuous development of differential circuit systems, more and more devices are designed into differential form, but the traditional magic T design scheme usually adopts a single-ended to single-ended port form, is not favorable for carrying out integrated design with the existing differential device, and does not meet the requirements of the existing differential communication system; in addition, the traditional magic T generally adopts a cavity or substrate integrated waveguide technology to generate filtering characteristics, but the technology has poor frequency band selectivity, cannot generate transmission zero points on two sides of a frequency band, and has the defects of high design difficulty and high processing cost in the prior art.
Aiming at the current situation, the invention develops simulation research and experimental tests, designs a single-ended to differential magic T with filtering characteristics, and referring to fig. 1, the structure of the single-ended to differential magic T with filtering characteristics is characterized in that a microstrip structure 2 is etched on the upper surface of a dielectric substrate 1, the lower surface of the dielectric substrate 1 is integrally a metal grounding plate 3, a gap structure is etched on the metal grounding plate 3, the longitudinal central line of the dielectric substrate 1 is the integral symmetrical axis of the upper surface microstrip structure 2 and the gap structure, the openings of U-shaped output microstrip feeder lines 6 at two ends of the upper surface microstrip structure 2 in the horizontal direction are outward, referring to fig. 1 and fig. 2, and the longitudinal central line of the dielectric substrate 1 is defined as a vertical axis AA'; a horizontal line of the dielectric substrate 1 is defined as a horizontal axis BB ', and the distance from the horizontal axis BB' to the lower edge of the dielectric substrate 1 is the longitudinal distance from the coupling point to the input end of the T-type input microstrip feed line 5, i.e. the lower edge of the dielectric substrate 1. The upper surface microstrip structure 2 comprises a single-end-to-differential reverse phase power distribution network formed by a single-end type J-shaped input microstrip feeder line 4 and a pair of differential type U-shaped output microstrip feeder lines 6, and an in-phase power distribution network formed by a single-end type T-shaped input microstrip feeder line 5 and a pair of differential type U-shaped output microstrip feeder lines 6; the upper surface of the medium substrate 1 is symmetrically provided with two power distribution networks with two functions, namely an in-phase output power distribution network and an anti-phase output power distribution network.
In the invention, the upper surface microstrip structure 2 is symmetrical about a vertical axis AA' except a J-shaped input microstrip feeder 4 positioned at the upper end of the dielectric substrate 1; the slot line structure on the metal grounding plate 3 is symmetrical about a vertical axis AA'; a pair of filter coupling output networks symmetrical about a vertical axis AA' exist in a single-ended to differential power distribution network, the filter coupling output networks provide the same filter coupling effect for two paths of output signals equally divided by power, a first L-shaped stepped impedance microstrip line 7 and a second L-shaped stepped impedance microstrip line 9 in an upper surface microstrip structure 2 in the filter coupling output network are symmetrically arranged to form a space capable of being inserted into a resonator, a stub loading type resonator 8 is positioned below the space, a first L-shaped stepped impedance slot line 12 and a second L-shaped stepped impedance slot line 13 in a slot structure are arranged above a projection space of the space capable of being inserted into the resonator on a metal grounding plate 3, and the whole filter coupling output network is symmetrical about a main stub central line of the stub loading type resonator 8.
In the invention, two metalized through holes 15 are respectively arranged at the tail ends of two branches of a T-shaped input microstrip feeder line 5, and referring to fig. 1 and 2, the T-shaped input microstrip feeder line 5 is connected with a lower metal grounding plate 3 to form a short circuit; in the invention, a metalized through hole 14 is arranged at the coupling end of the J-shaped input microstrip feeder line 4, and the J-shaped input microstrip feeder line 4 is connected with the lower metal grounding plate 3 to form a short circuit.
In the port form of the magic T, the prior art mainly adopts a single-end-to-single-end form. With the continuous development of differential circuit systems, more and more devices are designed into differential input forms, such as a differential antenna, a differential filter, a differential duplexer and the like, and the traditional transmission mode from single end to single end magic T does not meet the requirements of the existing differential system; in the filtering characteristic of the magic T, the prior art mainly adopts a cavity or substrate integrated waveguide technology to generate a resonance point, but the frequency band selectivity is poor, a transmission zero point cannot be generated outside the band, and the prior art has high design difficulty and high processing cost. With the development of modern communication technology, the research and design of the magic T are continuously improved and developed, but the existing magic T still has the defects of single structural form, poor frequency selectivity and low common-mode rejection capability. Therefore, the invention provides a technical scheme from single end to differential magic T with filtering characteristics through innovation, simulation and design repeated adjustment schemes, and aims at the problems in the existing magic T technology.
Example 2
The overall structure of the single-ended to differential magic T with the filtering characteristic is the same as that of embodiment 1, and the left half of the upper surface microstrip structure 2 of the invention is sequentially provided with a U-shaped output microstrip feeder 6 with an outward opening, a first L-shaped stepped impedance microstrip line 7, a stub loading resonator 8, a second L-shaped stepped impedance microstrip line 9 and the left half of a T-shaped input microstrip feeder 5 from left to right along a horizontal axis BB'. The T-shaped input micro-strip feeder 5 is formed by connecting a main path and two branch paths, the two branch paths of the T-shaped input micro-strip feeder 5 are bent upwards, a U-shaped structure formed by the two branch paths is connected with the main path positioned below, the T-shaped input micro-strip feeder 5 is symmetrical with respect to a vertical axis AA', a tuning fork structure is formed overall, and input single-ended signals can be converted into two paths of signals with equal power and phase. The input end of a main circuit of the T-shaped input micro-strip feeder 5 is positioned at the lower end of the dielectric substrate 1 in the vertical direction, and the length of a branch circuit extends to a position above a horizontal axis BB'; referring to fig. 2, the minor-pitch loaded resonator 8 has an E-shaped symmetric structure, and is composed of a main branch and two symmetric L-shaped branch branches, the whole is symmetrically distributed about a central line of the main branch as a symmetric axis, the central line of the main branch is parallel to the vertical axis AA', and the minor-pitch loaded resonator 8 is located in a space where the first L-shaped stepped impedance microstrip line 7 and the second L-shaped stepped impedance microstrip line 9 jointly form and can be inserted into the resonator. In other words, the first L-shaped stepped impedance microstrip line 7 and the second L-shaped stepped impedance microstrip line 9 of the present invention are also symmetrically distributed with the main branch center line of the branch loading resonator 8 as the symmetry axis, and the first L-shaped stepped impedance microstrip line 7 and the second L-shaped stepped impedance microstrip line 9 have the same structure and size. The first L-shaped stepped impedance microstrip line 7 is formed by connecting a first vertical coupling branch 7-1 and a first L-shaped short-circuit branch 7-2, the connection point of the first vertical coupling branch 7-1 and the first L-shaped short-circuit branch 7-2, namely a coupling point, is on a horizontal axis BB ', the length of the first L-shaped short-circuit branch 7-2 extending upwards from the connection point is a quarter of the medium wavelength of the center frequency, the first L-shaped short-circuit branch 7-2 is positioned above the horizontal axis BB', the tail end of the first L-shaped short-circuit branch 7-2 is an open circuit, an equivalent short circuit is formed at the connection point, namely the coupling point through quarter of the medium wavelength impedance transformation, the width of the first L-shaped short-circuit branch 7-2 is larger than the width of the first vertical coupling branch 7-1, namely the impedance of the first L-shaped short-circuit branch 7-2 is smaller than the impedance of the first vertical coupling branch 7-1, therefore, the wavelength and the length of the medium of the first L-shaped short-circuit branch 7-2 are relatively shortened, and the space occupied by the first L-shaped short-circuit branch 7-2 is saved. A gap is reserved between the first vertical coupling branch 7-1 and the branch loading type resonator 8 to generate coupling, the size of the gap influences the coupling strength, and the smaller the gap is, the larger the coupling strength is. The upper end of the upper surface microstrip structure 2 in the vertical direction is provided with a J-shaped input microstrip feeder line 4, the width of the J-shaped input microstrip feeder line 4 is consistent and uniform, the input end of the J-shaped input microstrip feeder line 4 is positioned at the upper end of the dielectric substrate 1 in the vertical direction, the J-shaped input microstrip feeder line 4 extends downwards to the position of the horizontal center line of the input end circular impedance slot line 16 in a manner of being parallel to the vertical axis AA', and then the trend of the microstrip line is changed from the vertical direction to the horizontal direction through a quarter circular arc structure tangent to the input end circular impedance slot line 16. The two U-shaped output microstrip feeder lines 6 are symmetrical about a vertical axis AA' and are respectively arranged at the left and right horizontal ends of the dielectric substrate 1, and the openings of the two U-shaped output microstrip feeder lines are outward.
The left half of the gap line structure on the metal grounding plate 3 is etched with an output end circular impedance gap line structure 10 and a first L-shaped stepped impedance gap line 12 connected with the output end circular impedance gap line structure from left to right along a horizontal axis, and the left half of a T-shaped gap line 11 connected with a second L-shaped stepped impedance gap line 13, wherein a gap is reserved between the first L-shaped open-circuit branch 12 and the second L-shaped open-circuit branch 13 to generate coupling, and the right half and the left half of the gap structure are completely symmetrical to provide the same phase change for output signals. The symmetry axis of the T-shaped slot line 11 coincides with the vertical axis AA ', the T-shaped slot line 11 includes a main line slot line 11-1 which is located upward from the horizontal axis BB ' and on the vertical axis AA ', two branch line slot lines 11-2 which are located on the horizontal axis BB ' and are symmetric with respect to the vertical axis AA ', and an input slot line 11-3 connected to the main line slot line 11-1, and can convert a single-ended signal input by the J-shaped input microstrip feed line 4 into two paths of signals with equal power and opposite phases. The tail end of an input slot line 11-3 of the T-shaped slot line 11 is provided with an input end circular impedance slot line 16, and a single-ended signal input by the J-shaped input microstrip feeder line 4 is input to the input slot line 11-3 through the structure. The first L-shaped stepped impedance gap line 12 and the second L-shaped stepped impedance gap line 13 have the same structural size, and the first L-shaped stepped impedance gap line 12 and the second L-shaped stepped impedance gap line 13 are symmetrically distributed by taking the projection of the main branch center line of the branch loading resonator 8 on the lower surface as a symmetry axis. The first L-shaped stepped impedance slot line 12 is formed by connecting a first transverse slot branch 12-1 and a first L-shaped slot open-circuit branch 12-2, the length of the first L-shaped open-circuit branch 12-2 is a quarter medium wavelength of a center frequency, the tail end of the first L-shaped open-circuit branch 12-2 of the slot structure is short-circuited, and an equivalent short circuit is formed at a connecting point, namely a coupling point, through quarter medium wavelength impedance transformation, the principle of the first L-shaped stepped impedance slot line is similar to that of the first L-shaped short-circuit branch 7-2, the width of the first L-shaped open-circuit branch 12-2 is larger than that of the first transverse slot branch 12-1, and the impedance of the first L-shaped open-circuit branch 12-2 is larger than that of the first transverse slot branch 12-1.
The circle center of the output end circular impedance slot line 10 is positioned on a horizontal axis BB ', the projection of the upper surface of the output end circular impedance slot line is tangent to a coupling end microstrip line 6-2 of the U-shaped output microstrip feeder line 6, and the tangent point is positioned at the midpoint of the coupling end microstrip line 6-2 and is positioned on the horizontal axis BB'. The projection of the first L-shaped stepped impedance slot line 12 on the upper surface is perpendicular to the first L-shaped stepped impedance microstrip line 7, and the projection of the midpoint of the stepped transformation position of the first L-shaped stepped impedance slot line 12 coincides with the connection point of the stepped transformation position of the first L-shaped stepped impedance microstrip line 7, so that cross coupling is generated. The invention adopts two forms of microstrip coupling modes: the first one is to convert the open-circuit end into short circuit at the coupling point through quarter wavelength, i.e. the first L-shaped stepped impedance microstrip line 7; the first is to place a short-circuited metallized via, i.e. metallized via 15, directly above the coupling point. The invention adopts two forms of gap coupling modes: the first is to convert the short-circuit end into an open circuit at the coupling point by a quarter wavelength, i.e. the first L-shaped stepped impedance slot line 12; the second is to use a circular impedance slot line to generate an open circuit effect at the coupling point, such as the output circular impedance slot line 10. The single-end to differential magic T with the filtering characteristic adopts various coupling structures, is used for realizing the transmission of energy between the microstrip line and the slot line, realizes a compact structure and excellent performance, and realizes the miniaturization of the magic T.
Example 3
A single-ended to differential magic T with filtering characteristics similar to embodiments 1-2, see figure 2,
according to the impedance matching principle, the impedance of the two branch slot lines 11-2 of the T-shaped slot line structure 11 of the present invention is equal to the impedance of the input slot branch 11-3 and is the impedance of the main path slot line 11-1
Doubling; the impedance of the branch microstrip line of the T-shaped input microstrip feeder line 5 is twice that of the main microstrip line. For the slot line, the wider the slot width of the slot line, the greater its impedance, so the width of the two branch slot lines 11-2 is equal to the input slot branch 11-3 and smaller than the width of the main path slot line 11-1; for the microstrip line, the wider the width of the microstrip line, the smaller the impedance, and therefore the width of the branch microstrip line of the T-type input microstrip feeder 5 is smaller than the width of the main microstrip line.
Example 4
The magic T from single end to differential end with filtering characteristics is the same as the embodiment 1-3, two input end microstrip lines 6-1 of two U-shaped output microstrip lines 6 connected with the side edge of a dielectric substrate 1, a main circuit microstrip line of a T-shaped input microstrip feeder 5 and a main circuit microstrip line of a J-shaped input microstrip feeder 4 are all 50 ohm microstrip lines, and the 50 ohm microstrip lines are general transmission lines in a radio frequency system and are matched with the existing system better, so that all external ports are set to be 50 ohms; the input end of the J-type input microstrip feeder line 4 is positioned at the upper edge of the dielectric substrate 1 and is positioned on the left side of a vertical axis AA ', the J-type input microstrip feeder line 4 firstly extends downwards in parallel with the vertical axis AA', then the trend of a microstrip line of the J-type input microstrip feeder line is changed from the vertical downwards direction to the horizontal leftwards direction through an arc structure, the coupling end of the J-type input microstrip feeder line is positioned on the right side of the vertical axis AA ', J-type ports can also be placed at symmetrical positions relative to the vertical axis AA', wherein the arc structure can also be changed into a right-angle structure, but the right-angle structure can bring higher loss to the feeder line, four boundaries of the dielectric substrate can be fully utilized for selection of the J-type input microstrip feeder line 4, and each boundary is provided with one port, so that the J-type input microstrip feeder line can be better connected with other systems; the widths of two input end microstrip lines 6-1 of the U-shaped output microstrip feeder line 6 are smaller than the widths of the coupling end microstrip lines 6-2, and the widths of the coupling end microstrip lines 6-2 can be adjusted according to the widths and the lengths of the coupled slot lines so as to match and reduce the loss of the ports.
Example 5
The single-ended to differential magic T with the filtering characteristic is the same as that of the embodiments 1-4, and the microstrip medium substrate 1 adopts the F4BM-2 material with the dielectric constant of 2.2, the size of 79.2mm multiplied by 84.8mm and the thickness of 0.8 mm. The widths of the two branch line 11-2 of the T-shaped slot line 11, the input slot line 11-3, the first transverse slot line 12-1 of the first L-shaped stepped impedance slot line 12 and the second transverse slot line 13-1 of the second L-shaped stepped impedance slot line 13 are all 0.1 mm. The plurality of slot lines have a transmission function in the magic T, and the plurality of microstrip lines in the magic T have the same width, namely the same impedance, so that the design analysis process can be simplified.
In this example, the optimum result is obtained when the width of the slot line is 0.1mm, and the width of the slot line is adjustable in actual operation, but the corresponding microstrip line structure needs to be adjusted to perform impedance matching.
A more detailed example is given below to further illustrate the invention
Example 6
A single-ended to differential magic T with filtering characteristics as in embodiments 1-5, with reference to figures 1 and 2. The invention comprises a dielectric substrate 1, an upper surface microstrip structure 2 and a lower surface metal grounding plate 3. The dielectric substrate 1 of the invention has a dielectric constant of 2.2 and a thickness of 0.8 mm.
Referring to fig. 2, in this example, two output microstrip lines 6-1 of two U-shaped output microstrip lines 6 disposed on the side of the dielectric substrate 1, the main microstrip line of the T-shaped input microstrip feed line 5, and the main microstrip line of the J-shaped input microstrip feed line 4 are all 50 ohm microstrip lines, referring to fig. 3, two output microstrip lines 6-1 of two U-shaped output microstrip lines 6, the main microstrip line of the T-shaped input microstrip feed line 5, and the J-shaped input microstrip feed line 4 are all w microstrip lines02.36 mm. Referring to fig. 3, in this example, the coupling end microstrip line 6-2 of the U-shaped output microstrip feeder 6 on the upper surface of the dielectric substrate 1 has a width w1The width of the coupling end microstrip line 6-2 can be adjusted according to the width and length of the coupled slot line, so as to match and reduce the loss of the port. The first L-shaped stepped impedance microstrip line 7 and the second L-shaped stepped impedance microstrip line 9 in the filter coupling network have the same structure and size, the first L-shaped stepped impedance microstrip line 7 is formed by connecting a first vertical coupling branch 7-1 and a first L-shaped short-circuit branch 7-2, and the first vertical coupling branch 7-1 is L in lengthf324mm wide by wf30.5mm, the first L-shaped short-circuit branch 7-2 has a length Lf415.6mm wide and wf40.6 mm. The width of the first L-shaped short-circuit branch 7-2 is larger than the width of the first vertical coupling branch 7-1, that is, the impedance of the first L-shaped short-circuit branch 7-2 is smaller than the impedance of the first vertical coupling branch 7-1, so that the wavelength and the length of a medium of the first L-shaped short-circuit branch 7-2 are relatively shortened, and the space occupied by the first L-shaped short-circuit branch 7-2 is saved. The first L-shaped stepped impedance microstrip line 7 and the second L-shaped stepped impedance microstrip line 9 are also symmetrically distributed by taking the main branch center line of the branch loading resonator 8 as a symmetry axis, and the distance between the L-shaped stepped impedance input microstrip line 6 and the L-shaped stepped impedance output microstrip line 7 is gsThe coupling strength is higher when the distance is smaller than 0.2 mm. Referring to fig. 3, the length l of the main branch of the branch-loading resonator 8f219.25mm, width wf2Total length l of two branch branches of branch-loaded resonator 8, 1.2mmf150.2mm, width wf10.5 mm. The length of the J-type input microstrip feeder line 4 can be adjusted according to the size of the dielectric substrate 1, the inner radius of the circular arc structure of the J-type input microstrip feeder line 4 is equal to the radius of the input end circular impedance slot line 16, and the radius rsThe coupling strength can be improved by the arc structure of the J-type input microstrip feed line 4 being tangent to the input end circular impedance slot line 16, which is 5.78 mm. Length l of main path microstrip line of T-type input microstrip feeder 52The thickness of the T-shaped input microstrip feeder 5 can be adjusted according to the size of the dielectric substrate 1, the structure of the T-shaped input microstrip feeder 5 is a tuning fork structure, the semi-circular arc radius r of the tuning fork part is 1.62mm, and the branch microstrip line length l of the T-shaped input microstrip feeder 5 is equal to320.15 mm. According to the impedance matching principle, the impedance of the branch microstrip line of the T-type input microstrip feeder 5 is twice that of the main microstrip line, so that the branch microstrip line impedance is 100 ohms, and the correspondingly calculated and optimized width w2 is 0.85 mm.
Referring to fig. 2, the left half of the slot line structure on the metal ground plate 3 is etched with an output end circular impedance slot line structure 10 and a first L-shaped stepped impedance slot line 12 connected thereto, and a T-shaped slot line 11 connected to a second L-shaped stepped impedance slot line 13, sequentially from left to right along a horizontal axisWherein a gap is left between the first L-shaped open-circuit branch 12 and the second L-shaped open-circuit branch 13, and a gap g is left between the first L-shaped open-circuit branch 12 and the second L-shaped open-circuit branch 13s2The coupling is generated 2.6mm, and the right half and the left half of the slot structure are completely symmetrical, so that the same phase change is provided for the output signals. Referring to fig. 4, the circular impedance slot line structure 10 with the left and right output ends and the slot line for transmission function form two connection points, and the distance l between the two connection pointss354.8 mm. Referring to fig. 4, the first L-shaped stepped impedance slot line 12 and the second L-shaped stepped impedance slot line 13 have the same structural size, and the first L-shaped stepped impedance slot line 12 and the second L-shaped stepped impedance slot line 13 are symmetrically distributed by taking the projection of the main branch center line of the branch loading resonator 8 on the lower surface as a symmetry axis. The first L-shaped stepped impedance slot line 12 is formed by connecting a first transverse slot branch 12-1 and a first L-shaped slot open-circuit branch 12-2, the length of the first L-shaped open-circuit branch 12-2 is a quarter medium wavelength of a center frequency, the tail end of the first L-shaped open-circuit branch 12-2 of the slot structure is short-circuited, and an equivalent short circuit is formed at a connecting point, namely a coupling point, through quarter medium wavelength impedance transformation, the principle of the first L-shaped stepped impedance slot line is similar to that of the first L-shaped short-circuit branch 7-2, the width of the first L-shaped open-circuit branch 12-2 is larger than that of the first transverse slot branch 12-1, and the impedance of the first L-shaped open-circuit branch 12-2 is larger than that of the first transverse slot branch 12-1. Length L of first L-shaped open-circuit branch 12-2s413mm wide ws41 mm. Referring to fig. 4, the impedance of the two branch slot lines 11-2 of the T-shaped slot line structure 11 is equal to the impedance of the input slot branch 11-3 and is the impedance of the main path slot line 11-1 according to the impedance matching principle
According to the theory, the main road slot line width w of the T-shaped slot line 11 is obtained by calculation and optimizations20.6mm, length ls2Two branch lines 11-2 and an input line 11-3 of the T-shaped slot line 11, which are 25.7mm, are all wsAs a result, the thickness was 0.1 mm. A first transverse slot line 12-1 of the first L-shaped stepped impedance slot line 12 and a second L-shaped stepped impedanceThe second transverse slot line 13-1 of the anti-slot line 13 is of equal width ws＝0.1mm。
The invention will be explained below with reference to the design principle and operation of the magic T
Example 7
A single-ended to differential magic T having a filtering characteristic, which has two operating states of an inverted power evenly-distributed output state and an in-phase power evenly-distributed output state, as in embodiments 1 to 6; when a single-ended signal is input from the J-type input microstrip feeder line 4, an output state is averagely allocated for reverse phase power, the single-ended signal is input through the J-type input microstrip feeder line 4, a coupling effect is generated between the short-circuit end of the J-type input microstrip feeder line 4 and the input slot line 11-3, the signal is transmitted to the main path slot line 11-1 and then transmitted to the left and right branch slot lines 11-2, because the T-type slot line 11 has the capability of averagely allocating the power of the signal, and the signal after the average power allocation has opposite phases, the signal on the left branch slot line 11-2 is transmitted to the second L-type stepped impedance slot line 13, and the process of transmitting the signal from the second transverse slot line 13-1 to the U-type output microstrip feeder line 6 is called a coupling filtering output process: the process couples the signal on the second transverse slot line 13-1 to the second L-shaped stepped impedance microstrip line 9, and further couples the signal to the stub loading type resonator 8 through the parallel of the microstrip lines, so as to realize the filtering function and generate a first transmission zero point, and then transmits the signal to the left U-shaped output microstrip feeder line 6 for output through the first L-shaped stepped impedance microstrip line 7 and the first L-shaped stepped impedance slot line 12, in particular, a source-load coupling effect is generated between the second L-shaped stepped impedance slot line 13 and the first L-shaped stepped impedance slot line 12 to generate a second transmission zero point, and the two transmission zero points enable the single-ended to differential magic T with the filtering characteristic to generate high selectivity. Similarly, the signal of the right branch is subjected to the filtering coupling output process of the right side, but the phase of the signal after passing through the T-shaped slot line 11 is the same as the initial phase of the signal of the right side, so that the phase of the signal output by the U-shaped output microstrip feed line 6 of the right side is the same as the phase of the signal output by the U-shaped output microstrip feed line 6 of the left side, and the output state of the inverted power average distribution is realized.
When a single-ended signal is input by the T-shaped input microstrip feeder line 5, the same-phase power is in an evenly-distributed output state, the single-ended signal is input through the main path of the T-shaped input microstrip feeder line 5, the T-shaped input microstrip feeder line 5 evenly distributes the power of the signal, the signal after the power is evenly distributed has the same phase, the left and right signals with the same power phase generate a coupling effect through the short-circuit tail ends of the two branches of the T-shaped input microstrip feeder line 5 and the second L-shaped stepped impedance slot lines 13 at the left and right ends to enter the coupling filtering output process, and finally, a pair of differential output signals with the same power phase are obtained on the U-shaped output microstrip feeder lines 6 at the left and right ends.
Meanwhile, a high degree of isolation is provided between input ports and between output ports. The magic T with the single-end-to-differential structure can eliminate external noise interference on the premise of ensuring the working characteristics of the magic T, and is directly connected with devices such as a differential antenna and the like. Meanwhile, the magic T from the single end of the filter structure to the difference is introduced, so that the communication efficiency is improved, the channel congestion condition is relieved, the transmission zero point is increased, and the frequency selectivity is improved. The invention can effectively improve the space utilization rate and the integration level, reduce the design complexity, and can be widely applied to a mobile wireless communication system as a basic radio frequency device.
The effects of the present invention will be further described by combining simulation and actual measurement experiments
Example 8
A single-ended to differential magic T with filtering characteristics as in embodiments 1-7,
simulation and test environment:
the simulation tool of the invention is electromagnetic simulation software HFSS-15.0, in the range of 1.0-4GHz, the frequency response of the single end to difference magic T with the filter characteristic of the invention is simulated, the experimental result of the change with frequency of the return loss and the insertion loss in the output state of the average distribution of the reverse phase power is shown in figure 5,
the actual measurement experiment of the present invention was carried out using a vector network analyzer N5230A, and a single-ended to differential magic T having a filtering characteristic, in this case, the results of frequency-dependent experiment of return loss and insertion loss in the output state of the reverse power equal distribution are shown in fig. 5,
referring to fig. 5, fig. 5 is an S parameter simulation and actual measurement diagram of the reverse phase power distribution time difference mode return loss and the differential mode insertion loss of the present invention, which is an experimental result of the change of the return loss and the insertion loss with frequency when the magic T of the present invention is in the reverse phase power average distribution output state, and the abscissa in fig. 5 is frequency in GHz and the ordinate is the differential mode return loss and the differential mode insertion loss in dB. In FIG. 5, a solid line with a symbol of a rectangle indicates the differential mode return loss | S11Simulation curve of | dotted line represents differential mode return loss | S21The actual measurement curve of | is accompanied by an inverted triangle symbol solid line to represent the differential mode insertion loss | S11Simulation curve of | dotted line represents differential mode insertion loss | S21The measured curve of l. As can be seen from FIG. 5, the differential mode return loss | S11I sum and differential mode insertion loss S21And the I simulation actual measurement results are overlapped. The center frequency of the differential mode passband of the invention is 2.29GHz, the relative bandwidth is 21.3%, and the maximum differential mode return loss | S11| is 22dB, minimum differential mode insertion loss | S21And | is 3.7dB, two transmission zeros are respectively arranged at two sides of the passband and are respectively positioned at 1.96GHz and 2.81 GHz. Referring to fig. 1, the branch-node loaded resonator 8 is introduced to implement a filtering function and generate a first transmission zero, and then is transmitted to the left U-shaped output microstrip feeder 6 for output through the first L-shaped stepped impedance microstrip line 7 and the first L-shaped stepped impedance slot line 12, and particularly, a source-load coupling effect is generated between the second L-shaped stepped impedance slot line 13 and the first L-shaped stepped impedance slot line 12 to generate a second transmission zero. The simulation result is highly consistent with the actual measurement result, and the design process is accurate and the simulation method is reasonable.
Example 9
The single-ended to differential magic T with filtering characteristics is the same as examples 1-7, and the simulated experimental environment is the same as example 8.
Referring to fig. 6, fig. 6 is an S parameter simulation and actual measurement diagram of the return loss and the insertion loss of the in-phase power distribution time difference mode of the invention, which is an experimental result of the change of the return loss and the insertion loss with frequency when the magic T of the invention is in the output state of the average distribution of the reverse phase power, and the abscissa in fig. 6 is frequency in GHz and the ordinate is the return loss and the insertion loss of the difference mode in dB. In FIG. 6, a solid line with a symbol of a rectangle indicates the differential mode return loss | S11Simulation curve of | dotted line represents differential mode return loss | S21The actual measurement curve of | is accompanied by an inverted triangle symbol solid line to represent the differential mode insertion loss | S11Simulation curve of | dotted line represents differential mode insertion loss | S21The measured curve of l. As can be seen from FIG. 6, the differential mode return loss | S11I sum and differential mode insertion loss S21And the I simulation actual measurement results are overlapped. The center frequency of the differential mode passband of the invention is 2.32GHz, the relative bandwidth is 21.6%, and the maximum differential mode return loss | S11| 23dB, minimum differential mode insertion loss | S21And | is 3.33dB, two transmission zeros are respectively arranged at two sides of the passband and are respectively positioned at 1.97GHz and 2.77 GHz.
The results of fig. 5 and fig. 6 both show that the single-ended to differential magic T with filtering characteristics of the present invention can eliminate external noise interference on the premise of ensuring its own operating characteristics, implement filtering functions by a simpler structure, and introduce two transmission zeros to make the single-ended to differential magic T with filtering characteristics of the present invention generate high selectivity, improve communication efficiency, and alleviate channel congestion.
Example 10
The single-ended to differential magic T with filtering characteristics is the same as examples 1-9, and the simulated experimental environment is the same as examples 8 and 9.
FIG. 7 shows a single end with filtering characteristics of the present inventionAn S parameter simulation and actual map of the isolation to differential magic T, with the abscissa in fig. 7 being frequency in GHz and the ordinate being differential mode return loss and differential mode insertion loss in dB. In FIG. 7, a solid line with a symbol attached indicates a simulation result curve, and a dotted line and a chain line indicate an actual measurement result curve, wherein a solid line with a symbol with a circle indicates an isolation | S between input portsInput portSimulation curve of | dotted line represents differential mode return loss | SInput portThe actual measurement curve of | is accompanied by a solid line with a rectangular symbol to represent the differential mode insertion loss | SOutput portSimulation curve of | dotted line represents differential mode insertion loss | SOutput portThe measured curve of (a). As can be seen from figure 7, the magic T has high isolation between the input ends and the output ends, and the isolation between the input ends is more than 36.77dB and the isolation between the input ends is more than 19.73dB in the range of 1GHz to 4 GHz.
Example 11
The single-ended to differential magic T with filtering characteristics is the same as examples 1-10, and the simulated experimental environment is the same as examples 8, 9 and 10.
Fig. 8 is a simulation and actual map of S parameter of phase consistency of magic T in the present invention, where the abscissa in fig. 8 is frequency in GHz, the left ordinate is output port phase difference of the present invention in the same-phase power distribution in deg, and the right ordinate is output port phase difference of the present invention in the opposite-phase power distribution in deg. In fig. 8, a solid line with a symbol indicates a simulation result curve, and a dotted line and a dashed line indicate an actual measurement result curve, where a solid line with a rectangular symbol indicates a simulation curve of an output port phase difference in the in-phase power distribution, a dotted line indicates an actual measurement curve of an output port phase difference in the in-phase power distribution, a solid line with a circular symbol indicates a simulation curve of an output port phase difference in the reverse-phase power distribution, and a dashed line indicates an actual measurement curve of an output port phase difference in the reverse-phase power distribution. It can be seen from fig. 8 that, in the output state of the equal distribution of the reverse phase power and the output state of the equal distribution of the same phase power, the phase difference error of the two output ports is kept within ± 1.48 ° within the filter passband. Compared with the prior art, the phase difference detection method has the advantages of small phase difference error and good consistency of output signals.
In short, the single-ended to differential magic T with the filtering characteristic disclosed by the invention solves the problems that the conventional magic T is poor in frequency band selectivity, single in port form and not beneficial to processing and integration. The invention is characterized in that a single-end to differential reverse-phase and in-phase power distribution network is arranged on the upper surface of a dielectric substrate, a pair of mutually symmetrical filter coupling output networks is arranged in the power distribution network, and the two networks are integrally connected through various types of microstrip-to-slot conversion structures. The filter coupling output network of the invention inserts and couples the branch loading type resonator through the L-shaped microstrip line and the L-shaped slot line structure. The invention improves the frequency band selectivity, effectively improves the space utilization rate and the integration level by increasing the transmission zero point, reduces the design complexity by introducing the single end to the differential port, has the advantages of low introduced noise and strong anti-interference capability, and is used as a novel radio frequency microwave device applied to a wireless communication system.
Claims (5)
1. A magic T with filtering characteristics from single end to difference is characterized in that a micro-strip structure (2) is etched on the upper surface of a dielectric substrate (1), a metal grounding plate (3) is integrally arranged on the lower surface of the dielectric substrate (1), a slot structure is etched on the metal grounding plate (3), the longitudinal center line of the dielectric substrate (1) is the integral symmetry axis of the micro-strip structure (2) and the slot structure, and the openings of U-shaped output micro-strip feeders (6) at two ends of the micro-strip structure (2) in the horizontal direction are outward; the microstrip structure (2) comprises a single-end-to-differential reverse phase power distribution network formed by a single-end type J-shaped input microstrip feeder line (4) and a pair of differential type U-shaped output microstrip feeder lines (6) and an in-phase power distribution network formed by a single-end type T-shaped input microstrip feeder line (5) and a pair of differential type U-shaped output microstrip feeder lines (6); the microstrip structure (2) is symmetrical about a vertical axis AA' except for a J-shaped input microstrip feeder (4) positioned at the upper end of the dielectric substrate (1); the slot line structure on the metal grounding plate (3) is symmetrical about a vertical axis AA'; a pair of filter coupling output networks symmetrical about a vertical axis AA 'exist in a single-ended to differential power distribution network, a first L-shaped stepped impedance microstrip line (7) and a second L-shaped stepped impedance microstrip line (9) in a microstrip structure (2) in the filter coupling output network are symmetrically arranged to form a space capable of being inserted into a resonator, a stub loading type resonator (8) is positioned below the space, a first L-shaped stepped impedance slot line (12) and a second L-shaped stepped impedance slot line (13) in a slot structure are arranged above a projection space of the space capable of being inserted into the resonator on a metal ground plate (3), the whole filter coupling output network is symmetrical about a main stub center line of the stub loading type resonator (8), and the main stub center line is parallel to the vertical axis AA'; the tail ends of two branches of the T-shaped input micro-strip feeder line (5) are respectively provided with two metallized through holes (15) to connect the T-shaped input micro-strip feeder line (5) with the lower metal grounding plate (3); the coupling end of the J-shaped input micro-strip feeder line (4) is provided with a metalized through hole (14) for connecting the J-shaped input micro-strip feeder line (4) with the lower metal grounding plate (3).
2. The single-ended to differential magic T with the filtering characteristic as claimed in claim 1, wherein the left half of the microstrip structure (2) is provided with a U-shaped output microstrip feed line (6), a first L-shaped stepped impedance microstrip line (7), a stub loading resonator (8), a second L-shaped stepped impedance microstrip line (9) and the left half of a T-shaped input microstrip feed line (5) in sequence from left to right along a horizontal axis BB'; the T-shaped input micro-strip feeder line (5) is formed by connecting a main path and two branch paths, the two branch paths of the T-shaped input micro-strip feeder line (5) are bent upwards, a U-shaped structure formed by the two branch paths is connected with the main path positioned below, the T-shaped input micro-strip feeder line (5) is symmetrical about a vertical axis AA ', the input end of the main path is positioned at the lower end of the medium substrate (1) in the vertical direction, and the length of the branch paths extends to a position above a horizontal axis BB'; the branch loading type resonator (8) is of an E-shaped symmetrical structure and is composed of a main road branch and two symmetrical L-shaped branch branches, the whole body is symmetrically distributed around the central line of the main road branch as a symmetrical axis, and the branch loading type resonator (8) is positioned in a space which is formed by the first L-shaped stepped impedance microstrip line (7) and the second L-shaped stepped impedance microstrip line (9) and can be inserted into the resonator; the first L-shaped stepped impedance microstrip line (7) is formed by connecting a first vertical coupling branch (7-1) and a first L-shaped short-circuit branch (7-2), the connection point of the first L-shaped stepped impedance microstrip line is also the coupling point on a horizontal axis BB ', the length of the first L-shaped short-circuit branch (7-2) extending upwards from the connection point is a quarter wavelength, the width of the first L-shaped short-circuit branch is larger than the width of the first vertical coupling branch (7-1), and the first L-shaped short-circuit branch (7-2) is positioned above the horizontal axis BB'; the upper end of the micro-strip structure (2) in the vertical direction is provided with a J-shaped input micro-strip feeder line (4), the width of the J-shaped input micro-strip feeder line (4) is consistent and uniform, the input end of the J-shaped input micro-strip feeder line is positioned at the upper end of the medium substrate (1) in the vertical direction, the J-shaped input micro-strip feeder line (4) firstly extends downwards to the position of the horizontal center line of the input end circular impedance slot line (16) in a manner of being parallel to the vertical axis AA', and then the trend of the micro-strip line is changed from the vertical direction to the horizontal direction through a quarter circular arc structure tangent to the input end circular impedance slot line (16); the two U-shaped output microstrip feeder lines (6) are symmetrical about a vertical axis AA' and are respectively arranged at the horizontal left end and the horizontal right end of the dielectric substrate (1);
the left half side of a gap line structure on a metal grounding plate (3) is etched with an output end circular impedance gap line structure (10), a first L-shaped stepped impedance gap line (12) connected with the output end circular impedance gap line structure and the left half side of a T-shaped gap line (11) connected with a second L-shaped stepped impedance gap line (13) along a horizontal axis from left to right in sequence, wherein a gap is reserved between the first L-shaped open-circuit branch (12) and the second L-shaped open-circuit branch (13) to generate coupling; the symmetry axis of the T-shaped slot line (11) is coincident with the vertical axis AA ', the T-shaped slot line (11) comprises a main path slot line (11-1) which is upward from the horizontal axis BB ' and is positioned on the vertical axis AA ', two branch path slot lines (11-2) which are positioned on the horizontal axis BB ' and are symmetrical relative to the vertical axis AA ', and an input slot line (11-3) connected with the main path slot line (11-1); the tail end of an input gap line (11-3) of the T-shaped gap line (11) is provided with an input end circular impedance gap line (16); the first L-shaped stepped impedance slit line (12) is formed by connecting a first transverse slit branch (12-1) and a first L-shaped slit open-circuit branch (12-2), the length of the first L-shaped open-circuit branch (12-2) is a quarter wavelength, and the width of the first L-shaped stepped impedance slit line is greater than that of the first transverse slit branch (12-1);
the circle center of the output end circular impedance slot line (10) is positioned on a horizontal axis BB ', the projection of the upper surface of the output end circular impedance slot line is tangent to a coupling end microstrip line (6-2) of the U-shaped output microstrip feeder line (6), and the tangent point is positioned at the middle point of the coupling end microstrip line (6-2) and is positioned on the horizontal axis BB'; the projection of the first L-shaped stepped impedance slot line (12) on the upper surface is vertical to the first L-shaped stepped impedance microstrip line (7), and the projection of the middle point of the stepped transformation position of the first L-shaped stepped impedance slot line (12) is superposed with the connection point of the stepped transformation position of the first L-shaped stepped impedance microstrip line (7) to generate cross coupling.
3. Single-ended to differential magic T with filtering characteristics according to claim 2 characterized in that the impedance of the two branch slot lines (11-2) of the T-shaped slot line structure (11) is that of the main slot line (11-1)
Doubling; the impedance of the branch microstrip line of the T-shaped input microstrip feeder line (5) is twice that of the main microstrip line.
4. The single-ended to differential magic T with filtering characteristics according to claim 1, characterized in that the two input microstrip lines (6-1) of the two U-shaped output microstrip lines (6) connected to the sides of the dielectric substrate (1), the main microstrip line of the T-shaped input microstrip feed line (5), and the main microstrip line of the J-shaped input microstrip feed line (4) are all 50 ohm microstrip lines; the input end of the J-type input microstrip feeder line (4) is positioned at the upper edge of the dielectric substrate (1) and is positioned on the left of a vertical axis AA ', the J-type input microstrip feeder line (4) firstly extends downwards in parallel with the vertical axis AA ', the microstrip line trend is changed from the vertical downward direction to the horizontal leftward direction through an arc structure, and the coupling end of the J-type input microstrip feeder line is positioned on the right of the vertical axis AA '; the widths of two input end microstrip lines (6-1) of the U-shaped output microstrip feeder line (6) are smaller than the width of the coupling end microstrip line (6-2).
5. The single-ended to differential magic T with filtering characteristics according to claim 2, characterized in that the microstrip dielectric substrate (1) is made of F4BM-2 material with dielectric constant of 2.2, size of 79.2mm x 84.8mm and thickness of 0.8 mm; the widths of two branch line gap lines (11-2) and an input gap line (11-3) of the T-shaped gap line (11), a first transverse gap line (12-1) of the first L-shaped stepped impedance gap line (12) and a second transverse gap line (13-1) of the second L-shaped stepped impedance gap line (13) are both 0.1 mm.
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