CN218039765U - Upper-layer microstrip structure of power division filter and double-frequency equal division Gysel power division filter - Google Patents

Abstract

The utility model provides a filter's upper microstrip structure is divided to merit, the upper microstrip structure of filter is divided to merit includes impedance transformation subassembly, branch's microstrip subassembly, open circuit microstrip subassembly and short circuit microstrip subassembly, impedance transformation subassembly's input and short circuit microstrip subassembly's one end connect gradually respectively the input port (I/P) of filter is divided to the merit, impedance transformation subassembly's first output reaches the one end of branch's microstrip subassembly is connected respectively the output port (O/P1) of filter is divided to the merit, impedance transformation subassembly's second output reaches the other end of branch's microstrip subassembly is connected respectively the output port (O/P2) of filter is divided to the merit, open circuit microstrip subassembly's one end is connected the middle-end of branch's microstrip subassembly. Simple structure and flexible adjustment.

Description

Upper-layer microstrip structure of power division filter and double-frequency equal division Gysel power division filter

Technical Field

The utility model belongs to the technical improvement field of power distribution, especially, relate to can use the dual-band bisector Gysel merit of the integrated dual-band filtering function at the radio frequency front end circuit and divide the wave filter.

Background

Power splitters and filters are common basic devices in rf front-ends. The power divider is used for carrying out two-path or multi-path power distribution and combination on signals. Filters are widely used in various fields of communication system circuits because they can separate a desired frequency band, playing an important role in processing signals and noise. They are often used simultaneously in microwave circuits.

Previous research on power splitters has focused primarily on broadening the band, reducing the area, dual frequency response, and harmonic suppression. Meanwhile, for the filter circuits with single passband and multiple passbands, how to reduce the volume, improve the frequency selectivity, flexibly control the working frequencies of different passbands and increase the transmission zero point is also a research focus of the passive microwave circuit.

The cascade use of the power divider and the filter not only can realize the function of signal distribution, but also can enable the signal to have good frequency selectivity, so that the design exists in many radio frequency subsystems. But the direct cascade connection and the independent optimization of the two not only lead to overlarge insertion loss, but also increase the circuit volume and the design difficulty due to matching adjustment between circuits. If the power divider and the filter circuit can be integrated on the circuit topology level, the purposes of circuit volume miniaturization and insertion loss reduction are achieved. In the past, many researches on Power division filters have been carried out, and authors in K.X.Wang, X.Y.Zhang and B.Hu, "Gysel Power Divider With impedance Power Ratios and Filter Responses Using Coupling Structure," in IEEE Transactions on Microwave Theory and Techniques, vol.62, no.3, pp.431-440, march 2014, propose a method for realizing the integrated design of the filter and the Power Divider by Using a Coupling Structure With 90-degree phase shift characteristic to replace an impedance conversion microstrip line in the traditional Gysel Power Divider. The method has the disadvantage that the requirement of the current mobile communication system for multi-band communication cannot be met.

The dual-band power divider and the filter are designed in a fusion mode. Many scholars propose a plurality of methods, but these researches are directed at Wilkinson power divider, and at present, the power divider and the filter fusion design under the dual-band are basically based on the Wilkinson structure, and the defects of these designs are mainly that no grounding point exists in the Wilkinson power divider, which can cause heat accumulation under the high-power scene. The Gysel power divider can work in a high-power scene due to the grounding design of a resistor device in an isolation network, but the fusion design of the Gysel power divider and a filter under a dual-frequency band is still vacant.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a power divider's upper microstrip structure, it is too big to aim at solving the insertion loss that leads to direct cascade, the independent optimization of power divider and wave filter, and the matching between the circuit is adjusted the circuit volume that leads to and the design degree of difficulty increases and current Wilkinson power divider can't be applicable to powerful technical problem.

The utility model discloses a realize like this, an upper microstrip structure of wave filter is divided to merit, the upper microstrip structure of wave filter is divided to merit includes impedance transformation subassembly, branch's microstrip subassembly, open circuit microstrip subassembly and short circuit microstrip subassembly, the input of impedance transformation subassembly and the one end of short circuit microstrip subassembly connect gradually respectively the input port (I/P) of wave filter is divided to the merit, the first output of impedance transformation subassembly reaches the one end of branch's microstrip subassembly is connected respectively the output port (O/P1) of wave filter is divided to the merit, the second output of impedance transformation subassembly reaches the other end of branch's microstrip subassembly is connected respectively the output port (O/P2) of wave filter is divided to the merit, the one end of opening circuit microstrip subassembly is connected the middle-end of branch's microstrip subassembly.

The utility model discloses a further technical scheme is: the impedance transformation component comprises two double-frequency filtering impedance transformers with 90-degree phase shift in different working frequency bands, and the two double-frequency filtering impedance transformers are horizontally and symmetrically coupled to form an upper half impedance transformer and a lower half impedance transformer.

The utility model discloses a further technical scheme is: the upper half impedance converter and the lower half impedance converter are the same and are formed by coupling a first resonator and a second resonator which are loaded based on a central branch and have half wavelength.

The utility model discloses a further technical scheme is: the first resonator in the upper half-impedance converter is the same as the second resonator, the first resonator comprises a first microstrip line, a second microstrip line, a third microstrip line and a fourth microstrip line, one end of the second microstrip line is connected with one end of the first microstrip line, one end of the fourth microstrip line is connected with the other end of the first microstrip line, one end of the third microstrip line is connected with the middle of the first microstrip line, the length of the third microstrip line is obtained according to the ratio of two working frequency points of the power divider, the length of the second microstrip line and the length of the fourth microstrip line are both greater than the length of the third microstrip line, the other end of the first microstrip line is further connected with an input port (I/P), the corresponding microstrip line of the second resonator is connected with a first output port (O/P1), and the corresponding microstrip line of the second resonator in the lower half-impedance converter is connected with a second output port (O/P2).

The utility model discloses a further technical scheme is: the second microstrip line, the third microstrip line and the fourth microstrip line are positioned on the same side of the first microstrip line, the second microstrip line, the third microstrip line and the fourth microstrip line are parallel to each other, and the distance between the third microstrip line and the second microstrip line is equal to the distance between the fourth microstrip line.

Another object of the utility model is to provide a wave filter is divided to dual-frenquency halving Gysel merit, dual-frenquency halving Gysel merit divide the wave filter to include upper microstrip structure.

The utility model discloses a further technical scheme is: the double-frequency equal-division Gysel power division filter further comprises an isolation element, a middle-layer dielectric plate and a lower-layer grounding metal plate, wherein the upper-layer microstrip structure and the isolation element are attached to the upper surface of the middle-layer dielectric plate, the lower-layer grounding metal plate is attached to the lower surface of the middle-layer dielectric plate, and two ends of the isolation element are respectively connected to the branch microstrip components in the upper-layer microstrip structure.

The beneficial effects of the utility model are that: the double-frequency equal-division Gysel power division filter can flexibly adjust the structure equivalent impedance and the bandwidth by adjusting the coupling strength and the port position between the resonators of the upper half or the lower half impedance converter; the length of the central branch knot is adjusted, and the second working frequency can be flexibly adjusted. And the requirements of matching and dual-frequency operation are further met by combining the design of the whole circuit topological structure. The Gysel power divider has the advantages of simple structure and flexible adjustment, not only retains the advantage that the Gysel power divider is suitable for high-power scenes, but also ensures that the signal has frequency selectivity under dual frequency bands.

Drawings

Fig. 1 is a schematic plane structure diagram of a dual-frequency equal division Gysel power division filter provided by the embodiment of the present invention.

Fig. 2 is a schematic plan view of an upper half impedance transformer of a dual-frequency filtering impedance transformer according to an embodiment of the present invention.

Fig. 3 is a transmission characteristic curve diagram of a dual-band equal-division Gysel power division filter according to an embodiment of the present invention.

Fig. 4 shows the return loss and the isolation coefficient of the output of the dual-band equal-division Gysel power division filter according to an embodiment of the present invention.

Detailed Description

The utility model discloses in, with the double-frequency filter that all has 90 degrees phase shift characteristics under two operating frequency and remove the quarter wavelength microstrip line in replacing the Gysel merit branch ware as the impedance transformer, the input/output impedance of impedance transformer can match through coupling strength and port position between the inside syntonizer of adjusting the impedance transformer, can realize the control to second operating frequency through the central minor matters length in adjusting the impedance transformer, its bandwidth also can be controlled through the transform of port position. Meanwhile, three transmission zeros are introduced at the edge of the pass band, so that the frequency selectivity of the signal can be improved. Because the power divider integrates the double-frequency filtering impedance converter, the functions of power distribution and frequency selection can be realized simultaneously.

An upper-layer microstrip structure of a power division filter comprises an impedance transformation assembly, a branch microstrip assembly, an open-circuit microstrip assembly and a short-circuit microstrip assembly, wherein the input end of the impedance transformation assembly and one end of the short-circuit microstrip assembly are respectively and sequentially connected with an input port (I/P) of the power division filter, the first output end of the impedance transformation assembly and one end of the branch microstrip assembly are respectively connected with an output port (I/P1) of the power division filter, the second output end of the impedance transformation assembly and the other end of the branch microstrip assembly are respectively connected with an output port (I/P2) of the power division filter, and one end of the open-circuit microstrip assembly is connected with the middle end of the branch microstrip assembly.

The impedance transformation component comprises two double-frequency filtering impedance transformers with 90-degree phase shift in different working frequency bands, and the two double-frequency filtering impedance transformers are horizontally and symmetrically coupled to form an upper half impedance transformer and a lower half impedance transformer.

The upper half impedance transformer and the lower half impedance transformer are the same and are formed by coupling a first resonator and a second resonator which are half the wavelength of the central branch.

The first resonator in the upper half-impedance converter is the same as the second resonator, the first resonator comprises a first microstrip line, a second microstrip line, a third microstrip line and a fourth microstrip line, one end of the second microstrip line is connected with one end of the first microstrip line, one end of the fourth microstrip line is connected with the other end of the first microstrip line, one end of the third microstrip line is connected with the middle of the first microstrip line, the length of the second microstrip line and the length of the fourth microstrip line are both larger than the length of the third microstrip line, the other end of the first microstrip line is further connected with an input port (I/P), the corresponding microstrip line of the second resonator is connected with a first output port (O/P1), and the corresponding microstrip line of the second resonator in the lower half-impedance converter is connected with a second output port (O/P2).

The length of the third microstrip line is obtained according to the ratio of two working frequency points of the power divider, the specific frequency is determined to satisfy the functional expression,

wherein L1 is the length of the impedance transformer excluding the center leg and L2 is the length of the center leg, so that a separate adjustment of L2 to adjust the second operating frequency can be achieved after the length of the resonator is fixed.

The second microstrip line, the third microstrip line and the fourth microstrip line are positioned on the same side of the first microstrip line, the second microstrip line, the third microstrip line and the fourth microstrip line are parallel to each other, and the distance between the third microstrip line and the second microstrip line is equal to the distance between the fourth microstrip line.

As shown in fig. 1, the utility model provides a wave filter is divided to dual-frenquency partition Gysel merit, the structure that the wave filter was divided to dual-frenquency partition Gysel merit includes the microstrip structure and the isolation element on upper strata, the ground connection metal sheet of medial base plate dielectric material and lower floor. The upper layer microstrip structure is attached to the upper surface of the middle layer dielectric slab, and the lower surface of the middle layer dielectric slab is grounded metal. The upper layer microstrip structure comprises two double-frequency filtering impedance transformers with 90-degree phase shift in different working frequency bands, four branch microstrip lines, an open-circuit microstrip line and a short-circuit microstrip line. The equivalent impedances of the two impedance converters are the same so as to realize equal power distribution, the input port (I/P) of the double-frequency equal division Gysel power division filter is shared as input, and the first output port (O/P1) and the second output port (O/P2) of the double-frequency equal division Gysel power division filter are respectively used as output. The four branch lines are connected in sequence at a first output port (O/P1) and a second output port (O/P2), the branch line characteristic impedance of the first branch line and the lower half isolation network which is horizontally symmetrical is the same, and the branch line characteristic impedance of the second branch line and the lower half isolation network which is horizontally symmetrical is the same. One end of the short-circuit microstrip line is indirectly connected with the input port (I/P), the other end of the short-circuit microstrip line is grounded through the via hole, one end of the open-circuit microstrip line is connected between the second wavelength branch line and the corresponding branch line of the lower semi-isolation network, and the other end of the open-circuit microstrip line is open-circuited. The isolation element comprises a first isolation resistor and a second isolation resistor, wherein the first isolation resistor is positioned between the first branch line and the second branch line, the second isolation resistor is positioned between the corresponding branch lines of the lower half isolation network, and the first isolation resistor and the second isolation resistor have the same impedance.

In the circuit, the first branch line, the second branch line, the open-circuit microstrip line and the short-circuit microstrip line have different characteristic impedances so as to realize good matching and isolation between the output ports. But to achieve the same circuit effect in the dual band, it has the same electrical length, satisfying (1 + m) ° θ = π. Wherein m is the ratio of the two working frequencies, and theta is the corresponding electrical length of the microstrip line under the first working frequency. .

In the dual-frequency equal-division Gysel power division filter, the upper half-impedance converter is formed by coupling two half-wavelength resonators including a central branch, and the two half-wavelength resonators are respectively a first resonator and a second resonator: the first resonator is composed of a first microstrip line, a second microstrip line, a third microstrip line and a fourth microstrip line, and one end of each of the second microstrip line, the third microstrip line and the fourth microstrip line is open-circuited; the second resonator is composed of a microstrip structure which is centrosymmetric with the first resonator. The superposition part of a second microstrip line of the first resonator and a microstrip line corresponding to the second resonator forms a first coupling structure, and the superposition part of a fourth microstrip line of the first resonator and a microstrip line corresponding to the second resonator forms a second coupling structure; the first microstrip line of the first resonator is connected with a common end point of the input port (I/P), the corresponding microstrip line of the second resonator is connected with the first output port (O/P1), and the lower half-impedance converter is composed of a microstrip coupling structure which is horizontally symmetrical to the upper half-impedance converter. One end of the short-circuit microstrip line is connected with the input port (I/P), and the other end of the short-circuit microstrip line is grounded through two via holes. The branch lines with different characteristic impedances are composed of an open-circuit microstrip line, a first branch line, a second branch line, symmetrical parts of the first branch line and the second branch line, and an isolation resistor. The first branch line is formed by a sixth microstrip line, the second branch line is formed by connecting a seventh microstrip line, an eighth microstrip line and a ninth microstrip line in sequence, and the lower half network and the upper half network are horizontally symmetrical. One end of the sixth microstrip line is connected with the first output port (O/P1), and the other end is connected with the seventh microstrip line. A first isolation resistor is connected between the first branch line and the second branch line, one end of the open-circuit microstrip line is connected between the second branch line and the corresponding branch line of the lower half network, the other end of the open-circuit microstrip line is open-circuit, a second isolation resistor is connected between the two corresponding branch lines of the lower half network, and one end of the corresponding branch line is connected with a second output port (O/P2).

The double-frequency equal-division Gysel power division filter can flexibly adjust the structure equivalent impedance and the bandwidth by adjusting the coupling strength and the port position between the resonators of the upper half or the lower half impedance converter; the length of the central branch knot is adjusted, and the second working frequency can be flexibly adjusted. And the requirements of matching and dual-frequency operation are further met by combining the design of the whole circuit topological structure. The Gysel power divider has the advantages of simple structure and flexible adjustment, not only retains the advantage that the Gysel power divider is suitable for high-power scenes, but also ensures that the signal has frequency selectivity under dual frequency bands.

In the dual-frequency equal-division Gysel power division filter, the length L of the half-wavelength resonator is one half of the wavelength lambda corresponding to the first resonant frequency f of the dual-frequency filtering impedance converter, and the length is the length of the actual microstrip line; the short-circuit microstrip line, the open-circuit microstrip line, the first branch line, the second branch line and the corresponding branch line of the lower half isolation network have the same electrical length and meet the condition that (1 + m) theta = pi: wherein m is the ratio of the two working frequencies, and theta is the corresponding electrical length of the microstrip line under the first working frequency. .

The second working frequency can be easily adjusted, the structure is simple, and the flexibility is high. Compared with the mode of cascade connection of the power divider and the filter, the method avoids the complexity of joint matching of multiple devices, has the performance of low insertion loss, is simpler in structure and smaller in size, and is beneficial to miniaturization of a communication system. The advantages that the Gysel power divider is suitable for high-power scenes are reserved, and signals of the Gysel power divider have frequency selectivity under double frequency bands.

As shown in fig. 1, the structure of the dual-frequency equal-division Gysel power division filter includes a microstrip structure and an isolation element on the upper layer, a substrate dielectric material on the middle layer, and a grounding metal plate on the lower layer. The upper layer microstrip structure is attached to the upper surface of the middle layer dielectric slab, and the lower surface of the middle layer dielectric slab is grounded metal. The utility model discloses characterized in that upper microstrip structure includes two double-frenquency filtering impedance converter that all have 90 degrees phase shifts in different operating frequency channels, four branch microstrip lines, an open circuit microstrip line and a short circuit microstrip line. The equivalent impedances of the two impedance converters are the same so as to realize equal power distribution, the input port (I/P) of the double-frequency equal division Gysel power division filter is shared as input, and the first output port (O/P1) and the second output port O/P2 of the double-frequency equal division Gysel power division filter are respectively used as output. The four branch lines are connected in sequence at a first output port (O/P1) and a second output port (O/P2), the branch line characteristic impedance of the first branch line and the lower half isolation network which is horizontally symmetrical is the same, and the branch line characteristic impedance of the second branch line and the lower half isolation network which is horizontally symmetrical is the same. One end of the short-circuit microstrip line is indirectly connected with the input port (I/P), the other end of the short-circuit microstrip line is grounded through the via hole, one end of the open-circuit microstrip line is connected between the second wavelength branch line and the corresponding branch line of the lower half isolation network, and the other end of the open-circuit microstrip line is open-circuited. The isolation element comprises a first isolation resistor R1 positioned between the first wavelength branch line 4 and the second wavelength branch line 5 and a second isolation resistor R2 positioned between the corresponding wavelength branch lines of the lower half isolation network, and the impedance of the first isolation resistor R1 is the same as that of the second isolation resistor R2.

As shown in fig. 1, in the dual-frequency equal-division Gysel power division filter, the upper half-impedance transformer is formed by coupling two half-wavelength resonators including a central stub, which are respectively a first resonator 1 and a second resonator 2: the first resonator 1 consists of a first microstrip line 7, a second microstrip line 8, a third microstrip line 9 and a fourth microstrip line 10, wherein one end of the second microstrip line 8, one end of the third microstrip line 9 and one end of the fourth microstrip line 10 are open-circuited; the second resonator 2 is composed of a microstrip structure which is centrosymmetric to the first resonator 1. The first microstrip line 7 of the first resonator 1 is connected with the input port (I/P), the corresponding microstrip line of the second resonator 2 is connected with the first output port (O/P1), and the lower half-impedance converter is composed of a microstrip coupling structure which is horizontally symmetrical to the upper half-impedance converter. One end of the short-circuit microstrip line 3 is connected with the input port (I/P), and the other end is grounded through two via holes. The branch lines with different characteristic impedances are composed of an open-circuit microstrip line 6, first and second branch lines 4 and 5, symmetrical parts of the first and second branch lines and isolation resistors R1 and R2. The first branch line is composed of a sixth microstrip line 4, the second branch line is composed of a seventh microstrip line 11, an eighth microstrip line 12 and a ninth microstrip line 13 which are connected in sequence, and the lower half network and the upper half network are horizontally symmetrical. One end of the sixth microstrip line 4 is connected to the first output port (O/P1), and the other end is connected to the seventh microstrip line 11. A first isolation resistor R1 is connected between the first branch line 4 and the second branch line 5, one end of an open-circuit microstrip line 6 is connected between the second branch line 5 and the corresponding branch line of the lower half network, the other end of the open-circuit microstrip line is open-circuit, a second isolation resistor is connected between two corresponding branch lines of the lower half network, and one end of the corresponding branch line is connected with a second output port (O/P2).

As shown in fig. 1, the length of the half-wavelength resonator is one half of the wavelength λ corresponding to the first resonant frequency f of the dual-band filtering impedance transformer, and the length is the actual microstrip line length; the short-circuit microstrip line, the open-circuit microstrip line, the first branch line, the second branch line and the corresponding branch line of the lower half isolation network have the same electrical length, and satisfy (1 + m) } theta = pi: wherein m is the ratio of the two working frequencies, and theta is the corresponding electrical length of the microstrip line under the first working frequency. .

Ensuring that the tangent value is constant means that the electrical length of the microstrip line other than the two 90 ° phase impedance transformers needs to satisfy the expression of (1 + m) × θ = pi, because the value of tan θ is used when calculating the equivalent impedance of the microstrip line, and tan θ = tan (pi- θ) is used here, and the electrical length varies with frequency. All that should be ensured here is that the tangent value to which the microstrip line electrical length corresponds is constant.

The double-frequency equal-division Gysel power division filter can flexibly adjust the structure equivalent impedance and the bandwidth by adjusting the coupling strength and the port position between the resonators of the upper half or the lower half impedance converter; the length of the central branch knot is adjusted, and the second working frequency can be flexibly adjusted. And the requirements of matching and dual-frequency operation are further met by combining the design of the whole circuit topological structure. The Gysel power divider has the advantages of simple structure and flexible adjustment, not only retains the advantage that the Gysel power divider is suitable for high-power scenes, but also ensures that the signal has frequency selectivity under dual frequency bands.

As shown in fig. 2, the first resonator 1 and the second resonator 2 in fig. 1: the two resonators are arranged in central symmetry, and the coupling strength between the resonators is changed by adjusting the coupling distance of the corresponding microstrip lines between the resonators and the length of the coupled microstrip lines. The lower half-impedance transformers are identical.

Examples

The structure of the double-frequency equal-division Gysel power division filter is shown in the figure I, the thickness of the dielectric substrate is 0.508mm, and the relative dielectric constant is 3.55.

Fig. 3 and 4 are simulation results of transmission characteristics of the dual-band equal division Gysel power division filter designed according to the above conditions. In the figure, the horizontal axis represents frequency, and the vertical axis represents transmission characteristics in dB. In fig. 3, S11 represents the input return loss of the double-frequency equal-division Gysel power division filter, S21 and S31 represent the insertion loss from the first output port (O/P1) and the second output port (O/P2) to the input port (I/P) when the input ports (I/P) are matched, respectively, and the simulation result shows that: the double-frequency equal-division Gysel power division filter has two working frequency points which are respectively 1.81GHz and 3.03GHz; the input return loss S11 is lower than-20 dB in a pass band near the working frequency point, is-35.1 dB at the working frequency point of about 1.81GHz, and is-25.6 dB at the working frequency point of about 3.03GHz; the insertion loss curves S21 and S31 are basically overlapped, and are-3.91 dB at the working frequency point of about 1.81GHz and-3.84 dB at the working frequency point of about 3.03GHz; the three transmission zeros are arranged near the two pass bands, so that the frequency selectivity of the filtering power divider is enhanced. In fig. 4, S22 and S33 represent output return losses of the first output port (O/P1) and the second output port (O/P2), respectively, and S23 represents an isolation coefficient of the first output port (O/P1) and the second output port (O/P2). The simulation result shows that: the output return loss curves S22 and S33 are basically superposed, the pass band near the working frequency point is lower than-20 dB, the working frequency point at 1.81GHz is-21.9 dB, and the working frequency point at 3.03GHz is-23 dB; the isolation coefficient S23 is lower than-15 dB in the whole pass band near the working frequency point, is-37.6 dB at the working frequency point of 1.81GHz, and is-24.2 dB at the working frequency point of 3.03 GHz.

Simulation results of the embodiment show that the double-frequency equal-division Gysel power division filter can realize double-frequency operation, equal-power distribution and filtering functions.

The above description is only exemplary of the present invention and should not be taken as limiting the scope of the present invention, as any modifications, equivalents, improvements and the like made within the spirit and principles of the present invention are intended to be included within the scope of the present invention.

Claims (8)

1. The upper-layer microstrip structure of the power division filter is characterized by comprising an impedance transformation assembly, a branch microstrip assembly, an open-circuit microstrip assembly and a short-circuit microstrip assembly, wherein the input end of the impedance transformation assembly and one end of the short-circuit microstrip assembly are respectively and sequentially connected with an input port (I/P) of the power division filter, the first output end of the impedance transformation assembly and one end of the branch microstrip assembly are respectively connected with an output port (O/P1) of the power division filter, the second output end of the impedance transformation assembly and the other end of the branch microstrip assembly are respectively connected with an output port (O/P2) of the power division filter, and one end of the open-circuit microstrip assembly is connected with the middle end of the branch microstrip assembly.

2. The upper microstrip structure of the power division filter according to claim 1, wherein the impedance transformation component comprises two dual-frequency filtering impedance transformers with 90-degree phase shift in different operating frequency bands, and the two dual-frequency filtering impedance transformers are horizontally and symmetrically coupled to form an upper half impedance transformer and a lower half impedance transformer.

3. The upper microstrip structure of claim 2 wherein the upper half-impedance transformer and the lower half-impedance transformer are identical and are each formed by coupling a first resonator and a second resonator of one-half wavelength based on the loading of the central stub.

4. The upper microstrip structure of the power division filter according to claim 3, wherein the first resonator in the upper half-impedance transformer is the same as the second resonator, the first resonator includes a first microstrip line, a second microstrip line, a third microstrip line and a fourth microstrip line, one end of the second microstrip line is connected to one end of the first microstrip line, one end of the fourth microstrip line is connected to the other end of the first microstrip line, one end of the third microstrip line is connected to the middle of the first microstrip line, the length of the second microstrip line and the length of the fourth microstrip line are both greater than the length of the third microstrip line, the other end of the first microstrip line is further connected to the input port (I/P), the corresponding microstrip line of the second resonator is connected to the first output port (O/P1), and the corresponding microstrip line of the second resonator in the lower half-impedance transformer is connected to the second output port (O/P2).

5. The upper microstrip structure of the power division filter according to claim 4, wherein the second microstrip line, the third microstrip line and the fourth microstrip line are located on the same side of the first microstrip line, the second microstrip line, the third microstrip line and the fourth microstrip line are parallel to each other, and a distance between the third microstrip line and the second microstrip line is equal to a distance between the fourth microstrip line.

6. A dual frequency equal division Gysel power division filter, characterized in that it comprises an upper microstrip structure according to any of claims 1-5.

7. The dual-band equal-division Gysel power-dividing filter according to claim 6, further comprising an isolation element, a middle dielectric plate and a lower grounding metal plate, wherein the upper microstrip structure and the isolation element are attached to the upper surface of the middle dielectric plate, the lower grounding metal plate is attached to the lower surface of the middle dielectric plate, and two ends of the isolation element are respectively connected to the branch microstrip components in the upper microstrip structure.

8. The dual-frequency equal-division Gysel power division filter according to claim 7, wherein the isolation element is an isolation resistor.

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