A high coupling directional coupler

Abstract

The application discloses a high-coupling directional coupler, which comprises two coaxial lines, a coupling tube and two coupling lines, the two coaxial lines are arranged in parallel, the two ends of the coupling tube are fixedly connected with the outer conductors of the two coaxial lines, forming an H-shaped structure, the two coupling lines are consistent in size and are stacked in the coupling tube with wide sides facing up and down, forming a wide-side coupling structure, the inner conductors in the outer conductors of the two coaxial lines are divided into upper inner conductors and lower inner conductors, and gaps are left between the upper inner conductors and the lower inner conductors, the two ends of the coupling line located in the upper layer are respectively inserted into the inner parts of the outer conductors of the two coaxial lines and are welded and fixed with the upper inner conductors, and the two ends of the coupling line located in the lower layer are respectively inserted into the inner parts of the outer conductors of the two coaxial lines and are welded and fixed with the lower inner conductors. The application has the advantages of small volume, simple structure, design and calculation of parameters of the wide-side coupling structure, precise adaptation of high coupling degree, low loss and high stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of directional coupler, and particularly relates to a high-coupling directional coupler. BACKGROUND

[0002] A coupler is a commonly used microwave device that can be used for power distribution or power synthesis, and is widely used in microwave circuit systems. The coupler can be a three-port or four-port device with loss or without loss. When there are only three ports, a T-shaped structure is mainly used, and the representative structure is a Wilkinson power divider. When there are four ports, the ports satisfy two-to-two isolation and the coupling of energy has directionality, which is called a directional coupler.

[0003] Regarding the directional coupler, S.B.Cohn first deduced the design formula of the wide-side coupling stripline in 1955 by the conformal transformation method combined with the analysis theory of the TEM wave odd-even mode impedance, and considered the influence of the stripline thickness on the coupling performance, thereby laying a foundation for the theoretical design of the wide-side directional coupler. However, for the specific requirements of the low-frequency band 40-100 MHz, the large power greater than or equal to 1.5 MW, and the low coupling degree-40 dB, the parameter design of the existing wide-side coupling structure lacks targeted solutions, and it is difficult to simultaneously meet the comprehensive indexes of directionality, voltage standing wave ratio (VSWR), field intensity limitation, and port adaptability, especially the signal reflection suppression and excessive coupling problem under large power transmission has not been effectively solved.

[0004] The existing high-coupling directional coupler has the problems of poor frequency band adaptability, insufficient power capacity, poor coupling degree precision and phase stability, lack of field intensity and voltage standing wave ratio control, and the like. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a high-coupling directional coupler, which has the advantages of small size, simple structure, design and calculation of parameters of the wide-side coupling structure, realization of precise adaptation of high coupling degree, and low loss and high stability.

[0006] The technical scheme of the present application is as follows:

[0007] The utility model provides a high coupling directional coupler, including two coaxial lines, a coupling tube and two coupling lines, two coaxial lines are arranged in parallel, and the outer conductor of two coaxial lines is fixedly connected with the both ends of coupling tube, forms H type structure, and the size of two coupling lines is identical and the wide side is opposite and is stacked in the coupling tube, forms the wide side coupling structure, and the inner conductor of two coaxial lines is divided into upper inner conductor and lower inner conductor, and the gap is left between upper inner conductor and lower inner conductor, and the width of gap is not more than the interval between two coupling lines, and the both ends of coupling line in upper layer are respectively penetrated to the inside of the outer conductor of two coaxial lines and are welded with upper inner conductor, and the both ends of coupling line in lower layer are respectively penetrated to the inside of the outer conductor of two coaxial lines and are welded with lower inner conductor.

[0008] The diameter of the coupling tube The width of the two coupling lines The interval between the two coupling lines Satisfies formula (1):

[0009] (1);

[0010] In formula (1), Represent odd mode characteristic impedance; Represent even mode coupling coefficient; Represent the inverse function of hyperbolic tangent function.

[0011] The even mode coupling coefficient The calculation is specifically seen formula (2):

[0012] (2);

[0013] In formula (2), Represent even mode intermediate parameter, The calculation is specifically seen formula (3):

[0014] (3);

[0015] In formula (3), Represent the relative dielectric constant of the air inside the coupling tube; Represent even mode characteristic impedance.

[0016] The even mode characteristic impedance And odd mode characteristic impedance The calculation formula is seen formula (4):

[0017] (4);

[0018] In formula (4), Represent the characteristic impedance of high coupling directional coupler, Coupling degree representing the high coupling directional coupler.

[0019] The interval between the two coupling lines 9-11mm.

[0020] The two coaxial lines are both nine-inch coaxial lines.

[0021] Advantages of the present application:

[0022] (1), the two coupling lines of the present application adopt a wide-side coupling structure, which precisely matches the coupling requirement of 3dB high coupling degree and 40-90MHz.

[0023] (2), the coupling line of the present application is directly welded and fixed with the inner conductor of the coaxial line, the connection structure is simple, and no additional connecting line is needed to connect the coupling line and the coaxial port, thus avoiding the coupling problem between the connecting lines, making the two coaxial lines form an upper and lower surface feeding port structure design, which has the advantages of good impedance matching and isolation degree, and low loss.

[0024] (3), the coupling line of the present application is arranged in the coupling tube, i.e. in the circular waveguide, which is better shielded from space electromagnetic interference, and is easy to connect with the coaxial line.

[0025] (4), the present application optimizes the size parameters of the high coupling directional coupler based on the odd-even mode impedance, realizes precise adaptation of high coupling degree (3dB), balances the coupling degree, standing wave ratio and field intensity limit, and finally realizes low loss and high stability. BRIEF DESCRIPTION OF DRAWINGS

[0026] Fig. 1 is a perspective view of the present application.

[0027] Fig. 2 is a longitudinal sectional view of the present application.

[0028] Fig. 3 is a transverse sectional view of the present application.

[0029] Reference signs: 1-coupling tube, 2-coupling line, 3-outer conductor of nine-inch coaxial line, 4-upper inner conductor, 5-lower inner conductor. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0031] See Figs. 1-3The utility model provides a high coupling directional coupler, including two nine inch coaxial lines, a coupling tube 1 and two coupling lines 2, two coaxial lines are arranged in parallel, the both ends of coupling tube 1 are fixedly connected with the outer conductor 3 of two nine inch coaxial lines respectively, form H type structure, the size of two coupling lines 2 is identical and the wide side is opposite and is stacked in coupling tube 1, form wide side coupling structure, the inner conductor in the outer conductor 3 of two nine inch coaxial lines is all divided into upper inner conductor 4 and lower inner conductor 5, and there is gap between upper inner conductor 4 and lower inner conductor 5, the width of gap is not more than the interval between two coupling lines, the both ends of coupling line 2 in upper layer are respectively inserted into the inside of the outer conductor 3 of two nine inch coaxial lines and are welded with upper inner conductor 4, the both ends of coupling line 2 in lower layer are respectively inserted into the inside of the outer conductor 3 of two nine inch coaxial lines and are welded with lower inner conductor 5,

[0032] The coupling tube 1 is grounded, the diameter of the coupling tube 1 is , the diameter of the coupling tube 1 is , the width of the two coupling lines 2 is , the interval between the two coupling lines 2 is satisfies the following formula (1):

[0033] (1);

[0034] In formula (1), represents the odd mode characteristic impedance; represents the even mode coupling coefficient; represents the inverse function of the hyperbolic tangent function;

[0035] The even mode coupling coefficient in formula (1) is calculated according to the following formula (2):

[0036] (2);

[0037] In formula (2), represents the intermediate parameter of the even mode, is calculated according to the following formula (3):

[0038] (3);

[0039] In formula (3), represents the relative permittivity of the air inside the coupling tube, when the dielectric plate inside the coupling tube is selected from high-temperature-resistant and high-power-resistant aluminum oxide ceramic or dielectric-stable and low-loss polytetrafluoroethylene, is the relative permittivity of the aluminum oxide ceramic or the polytetrafluoroethylene; represents the even mode characteristic impedance;

[0040] The even mode characteristic impedance and odd-mode characteristic impedance The calculation formula is shown in the following formula (4):

[0041] (4);

[0042] In equation (4), The characteristic impedance representing a highly coupled directional coupler. This represents the coupling degree of a highly coupled directional coupler.

[0043] A 3dB high-coupling directional coupler, with a spacing between the two coupling lines. Set to 10mm, the width of the two coupling lines The coupling line length is set to 60mm, and a segmented wideband adaptation design is implemented. When the 3dB high-coupling directional coupler is suitable for 40~65MHz, the two coupling lines are set to 1150mm, with a coupling degree ranging from -3.181dB to -2.846dB. When the 3dB high-coupling directional coupler is suitable for 65~90MHz, the coupling line length is set to 730mm, with a coupling degree ranging from -3.148dB to -2.959dB. Through the segmented wideband adaptation design, the high coupling degree requirements of different frequency bands are met, and the phase difference consistency error is ≤ ±2°.

[0044] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-coupling directional coupler characterized by: The application relates to a coaxial line coupling device, which comprises two coaxial lines, a coupling tube and two coupling lines, the two coaxial lines are arranged in parallel, the two ends of the coupling tube are fixedly connected with the outer conductors of the two coaxial lines, an H-shaped structure is formed, the two coupling lines are identical in size and are stacked in the coupling tube with the wide sides of the two coupling lines being opposite to each other, a wide-side coupling structure is formed, the inner conductors in the outer conductors of the two coaxial lines are divided into upper inner conductors and lower inner conductors, and gaps are left between the upper inner conductors and the lower inner conductors, the width of the gaps is not larger than the distance between the two coupling lines, the two ends of the coupling line in the upper layer are respectively inserted into the inner parts of the outer conductors of the two coaxial lines and are welded and fixed with the upper inner conductors, and the two ends of the coupling line in the lower layer are respectively inserted into the inner parts of the outer conductors of the two coaxial lines and are welded and fixed with the lower inner conductors. the diameter of the coupling tube the width of the two coupling lines the spacing between the two coupling lines satisfies the following equation (1): （1）； In formula (1), represents the relative permittivity of the air inside the coupling tube; represents the odd mode characteristic impedance; represents the coupling coefficient of the even mode; represents the inverse hyperbolic tangent function.

2. The high-coupling directional coupler of claim 1, wherein: The coupling coefficient of the even mode The calculation of the coupling coefficient of the even mode is shown in the following equation (2). （2）； In formula (2), the intermediate parameter representing the even mode, The calculation of the intermediate parameter is shown in the following formula (3). （3）； In formula (3), represents the relative permittivity of the air inside the coupling tube; represents the characteristic impedance of the odd mode.

3. The high-coupling directional coupler of claim 2, wherein: The even mode characteristic impedance and the odd mode characteristic impedance The calculation formula is shown in the following formula (4). （4）； In formula (4), representing a characteristic impedance of the high-coupling directional coupler, representing a coupling degree of the high-coupling directional coupler.

4. The high-coupling directional coupler of claim 1, wherein: The distance between the two coupling lines is set to 9-11 mm.

5. The high-coupling directional coupler of claim 1, wherein: The two coaxial lines are both nine-inch coaxial lines.

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