W-band microstrip-ultrathin waveguide power divider-microstrip structure

Abstract

The invention discloses a W-band microstrip-ultrathin waveguide power divider-microstrip structure, and belongs to the technical field of millimeter wave passive devices. The whole structure is in left-right mirror symmetry and comprises an ultrathin waveguide power divider, an input microstrip assembly arranged at the input end of the ultrathin waveguide power divider and two output microstrip assemblies arranged at the output end of the ultrathin waveguide power divider. The microstrip assembly comprises an air cavity, a dielectric substrate, a metal patch arranged on the front surface of the dielectric substrate, and a metal floor covering the back surface of the dielectric substrate. According to the invention, the height occupied by the waveguide power divider is reduced, the length of the transition structure is shortened, and the volume required by using the waveguide cavity power divider in a radio frequency circuit is greatly reduced; through the straight-through structure, the defect that an electric field rotates by 90 degrees due to a traditional fin line transition structure is avoided, and the field continuity is improved; the vertical arrangement of a traditional waveguide-probe-microstrip transition structure is avoided, and the circuit layout is facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of millimeter wave passive devices, and in particular relates to a W-band microstrip-ultra-thin waveguide power divider-microstrip structure. Background Art

[0002] With the rapid development of modern microwave millimeter wave circuit systems, W-band circuit systems have been widely used in various fields. In the field of wireless communications, millimeter waves have high spectrum bandwidth and transmission rate, so they are widely used in high-speed wireless LAN, broadband access, vehicle-mounted communications and other fields. In addition, millimeter waves are also used in military fields such as radar detection, satellite communications, and electronic warfare. Therefore, the requirements for the performance, volume, cost and other characteristics of W-band circuits and related passive components are getting higher and higher. However, the higher the frequency of the electromagnetic wave, the stronger its attenuation is compared with the low-frequency electromagnetic wave. Therefore, in the W-band RF circuit or antenna feeding circuit, power division, amplification, and combining methods are often used to increase the power of the signal in the circuit. Therefore, the power divider is indispensable in the RF circuit and plays a pivotal role in the communication system, which makes the design and research of the power divider always the focus of research. And how to make the power divider integrated and miniaturized is the top priority of research.

[0003] At present, the power divider of W band generally uses the standard waveguide power divider with large power capacity and low insertion loss, and the power divider is a separate module. The power divider module generally needs to be connected to the standard waveguide and connected to other RF active circuits through the fin line or microstrip probe transition structure. At present, these two commonly used transition structures have some defects. In the waveguide-fin line-microstrip transition structure, the fin-shaped metal on both sides of the dielectric substrate will rotate the electric field transmitted in the waveguide by 90 degrees, causing field discontinuity, which is not conducive to the matching of the circuit; at the same time, the volume required for the transition part of the fin line is large, which is not conducive to the miniaturization design of the system. In the waveguide-probe-microstrip transition structure, the rectangular waveguide and the microstrip line are often perpendicular to each other, making it difficult to realize the integration of the circuit. At the same time, both transition structures connect the microstrip line with the standard waveguide, and the standard waveguide has a large volume, which is not conducive to the miniaturization design of the circuit. This makes the power divider in the W band too large, which is a huge obstacle to the miniaturization of the overall circuit. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above structure and provide a W-band microstrip-ultra-thin waveguide power divider-microstrip structure. Under the premise that the overall performance of the structure of the present invention meets the engineering requirements, the power division, amplification, combination and signal output of the input signal are all completed on the same plane, and it has the advantages of miniaturization, integration, low insertion loss, low reflection and easy processing.

[0005] To achieve the above content, the technical solution adopted by the present invention is:

[0006] A W-band microstrip-ultra-thin waveguide power divider-microstrip structure, characterized in that the structure is mirror-symmetrical as a whole, comprising an ultra-thin waveguide power divider, an input microstrip component arranged at the input end of the ultra-thin waveguide power divider, and two output microstrip components arranged at the output end of the ultra-thin waveguide power divider;

[0007] The input microstrip assembly and the output microstrip assembly have the same structure, and both include: an air cavity, a dielectric substrate, a metal patch arranged on the front side of the dielectric substrate, and a metal floor covering the back side of the dielectric substrate;

[0008] The metal patch includes a microstrip line, a trapezoidal gradient conductive strip, and a conductive strip extension section connected in sequence;

[0009] The other end of the microstrip line is a signal input port or an output port;

[0010] The upper base of the trapezoidal tapered guide strip is the same as the line width of the microstrip line, and the lower base extends to the ultra-thin waveguide input end or the ultra-thin waveguide output end of the ultra-thin waveguide power divider through the guide strip extension section;

[0011] The air cavity is located directly above the dielectric substrate, and the surface of the air cavity close to the ultra-thin waveguide power divider is located above the extended section of the guide strip and perpendicular to the extended section of the guide strip, and the distance between the air cavity and the bottom of the trapezoidal gradient guide strip is within the range of 0 to 0.3 mm;

[0012] The ultra-thin waveguide power divider is T-shaped as a whole, and includes an ultra-thin input waveguide, two ultra-thin output waveguides, and matching grooves located in the same plane; the narrow side dimensions of the ultra-thin input waveguide and the ultra-thin output waveguide are the same as the overall thickness of the input microstrip component and the output microstrip component.

[0013] Furthermore, the ultra-thin input waveguide comprises a rectangular waveguide section and a trapezoidal gradient section; one end of the rectangular waveguide section is connected to the input microstrip component, and the other end is connected to two ultra-thin output waveguides through a trapezoidal gradient section with gradually increasing width;

[0014] The two ultra-thin output waveguides are perpendicular to the ultra-thin input waveguide and are arranged in opposite directions, and an inwardly concave isosceles triangle cut corner is arranged between the two ultra-thin output waveguides;

[0015] The matching groove is located at the vertex of the inwardly concave isosceles triangle cut angle, and the matching groove and the isosceles triangle cut angle together form a funnel-shaped groove.

[0016] Furthermore, the lower base of the trapezoidal gradient conductive strip is smaller than or equal to the width of the conductive strip extension section; and the conductive strip extension section has the same width as the dielectric substrate.

[0017] Furthermore, the trapezoidal gradient conductive strip is an isosceles trapezoidal metal patch.

[0018] Furthermore, the width of the dielectric substrate is less than or equal to the wide side dimensions of the ultra-thin input waveguide and the ultra-thin output waveguide.

[0019] Furthermore, the width of the air cavity is the same as the width of the dielectric substrate, and the height is in the range of 0.5 mm to 1.27 mm.

[0020] The technical solution principle of the present invention is:

[0021] Transmitting TE in a rectangular waveguide cavity power divider 10 Under the premise of single-mode transmission, reducing the height of the standard height waveguide cavity power divider will not affect its transmission characteristics. At the same time, reducing the height of the waveguide cavity power divider will reduce its input impedance as seen from the port, making it easier to match with the microstrip line part. Therefore, the dielectric substrate can be implemented with a variety of dielectric substrates, as long as the height of the ultra-thin waveguide power divider is always equal to the total thickness of the dielectric substrate and the metal on it.

[0022] In the microstrip component, on the one hand, the trapezoidal tapered guide strip is gradually widened to reduce the impedance, which is convenient for matching with the ultra-thin waveguide power divider; on the other hand, the tolerance during processing can be improved, that is, the air cavity formed by the metal inner wall of the circuit does not have to be tangent to the long bottom side of the trapezoidal tapered guide strip (the surface of the air cavity close to the input matching cavity or the output matching cavity is located above the guide strip extension section and perpendicular to the guide strip extension section, and the spacing from the lower bottom of the trapezoidal tapered guide strip is in the range of 0 to 0.3 mm, which basically does not affect the performance of the entire structure).

[0023] The basic structure of the ultra-thin waveguide power divider is H-plane branching, that is, the branch is on the narrow wall of the main waveguide and is connected to the H 10 The magnetic lines of force of the wave are parallel to the plane, also known as HT structure. In addition, rectangular grooves and right-angled triangle cut corners are designed at the branch to match the input and output ends, realizing the basic function of the power divider.

[0024] Compared with the prior art, the present invention has the following advantages and improvements:

[0025] The present invention breaks through the shackles of the traditional microstrip transition to the standard waveguide, and realizes an ultra-low insertion loss, straight-through, miniaturized integrated microstrip-ultra-thin waveguide power divider-microstrip structure without affecting the electromagnetic energy transmission characteristics of the microstrip-waveguide transition. Compared with the commonly used waveguide cavity power divider, the height occupied by the waveguide cavity power divider is reduced, the length of the transition structure is shortened, and the volume required for the use of the waveguide cavity power divider in the RF circuit is greatly reduced. And through the straight-through structure, the defect of the traditional fin-line transition structure that the electric field rotates 90 degrees is avoided, and the continuity of the field is improved; the vertical arrangement of the traditional waveguide-probe-microstrip transition structure is avoided, which facilitates circuit layout. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of a specific embodiment of the present invention;

[0027] Figure 2 is a side view of a microstrip assembly according to a specific embodiment of the present invention;

[0028] Figure 3 is an S parameter curve diagram of a specific embodiment of the present invention at 88 GHz to 102 GHz;

[0029] Figure 4 It is a phase curve diagram of a specific implementation mode of the present invention at 88 GHz to 102 GHz.

[0030] Explanation of the marks in the figure: 11. dielectric substrate, 12. microstrip line, 13. trapezoidal gradient guide strip, 14. guide strip extension section, 15. metal floor, 16. air cavity; 21. ultra-thin input waveguide rectangular waveguide section, 22. ultra-thin input waveguide trapezoidal gradient section, 23. matching groove, 24. cut corner, 25. ultra-thin output waveguide rectangular waveguide section. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and technical problem solved by the present invention clearer, the present invention is further quantitatively described below in conjunction with the accompanying drawings and specific examples.

[0032] This embodiment provides a W-band microstrip-ultra-thin waveguide power divider-microstrip structure, such as Figure 1 As shown, the structure is mirror-symmetrical as a whole, including an ultra-thin waveguide power divider, an input microstrip component arranged at the input end of the ultra-thin waveguide power divider, and two output microstrip components arranged at the output end of the ultra-thin waveguide power divider.

[0033] The input microstrip component and the output microstrip component have the same structure. Figure 2 As shown, they all include: an air cavity, a dielectric substrate, a metal patch arranged on the front side of the dielectric substrate, and a metal floor covering the back side of the dielectric substrate.

[0034] The dielectric substrate is Rogers Duroid 5880, with a relative dielectric constant of 2.2, a width of 1.9 mm and a thickness of 0.127 mm.

[0035] The thickness of the metal floor is 0.035 mm (taking into account that silver paste or solder will be used to fix the substrate circuit in actual use, which will increase the thickness of the lower metal layer at the bottom of the cavity).

[0036] The thickness of the metal patch is 0.018mm, and it includes a microstrip line, a trapezoidal tapered guide strip, and a guide strip extension section connected in sequence. The microstrip line is a 50-ohm microstrip line with a line width of 0.38mm, and the other end of the microstrip line is a signal input port or an output port; the upper base of the trapezoidal tapered guide strip is the same as the line width of the microstrip line, the lower base is 1.9mm long and 0.65mm high, and it extends to the ultra-thin waveguide input end or ultra-thin waveguide output end of the ultra-thin waveguide power divider through a guide strip extension section with a width of 1.9mm and a length of 0.68mm. The guide strip extension section and the dielectric substrate and metal floor directly below it together constitute a dielectric-filled waveguide, and the trapezoidal tapered guide strip combined with the dielectric-filled waveguide is used to transition the 50-ohm microstrip line to the matching cavity.

[0037] The air cavity is located directly above the dielectric substrate, the width of the air cavity is the same as the width of the dielectric substrate, and the height is 1.27 mm; the surface of the air cavity close to the ultra-thin waveguide power divider is located above the guide strip extension section and perpendicular to the guide strip extension section, and the distance from the lower bottom of the trapezoidal gradient guide strip is in the range of 0 to 0.3 mm.

[0038] The ultra-thin waveguide power divider is T-shaped as a whole, including an ultra-thin input waveguide, two ultra-thin output waveguides, and matching grooves located in the same plane; the total thickness of the dielectric substrate and the metal layer on its two side surfaces is 0.18 mm, so the narrow side size of the ultra-thin waveguide power divider is also 0.18 mm.

[0039] The ultra-thin input waveguide comprises a rectangular waveguide section with a wide side size of 2.54 mm and a length of 3.6 mm and a trapezoidal gradient section with an upper base of 2.54 mm, a lower base of 4.55 mm and a height of 3.5 mm; one end of the rectangular waveguide section is connected to the input microstrip component, and the other end is connected to two ultra-thin output waveguides through the trapezoidal gradient section.

[0040] The two ultra-thin output waveguides have a wide side dimension of 2.54 mm and a length of 5 mm, and are perpendicular to the ultra-thin input waveguide and arranged in opposite directions.

[0041] An inwardly concave isosceles triangle cut corner is set between the two ultra-thin output waveguides, the base length of the isosceles triangle cut corner is 5.21mm, and the height of the isosceles triangle cut corner is 1.99mm. A matching groove with a width of 0.39mm and a length of 0.55mm is set at the top corner of the inwardly concave isosceles triangle cut corner, and the matching groove and the isosceles triangle cut corner together form a funnel-shaped groove.

[0042] In this embodiment, the parts that cannot be processed into right angles or obtuse angles in actual processing are chamfered to simulate the rounded corners formed by a milling cutter with a radius of 0.3 mm, which is as close to actual processing as possible. Since the transition part of the present invention is a straight-through structure, there is no loss caused by electric field rotation or vertical structure, and the requirement of low insertion loss is achieved.

[0043] Figure 3 The insertion loss and reflection coefficient curves of this embodiment when working at 88GHz~102GHz are given. The maximum additional insertion loss in the 90GHz~100GHz passband is 0.65dB, which has low insertion loss performance; the maximum difference between the two output powers of the power divider at the same frequency point is 0.24dB, which has good consistency; the reflection coefficient is lower than -20dB in the passband.

[0044] Figure 4 The phase diagram of the embodiment when working at 88 GHz to 102 GHz is given. In the passband of 90 GHz to 100 GHz, the maximum difference between the two output signals at the same frequency point is 0.04 degrees, which has good consistency.

[0045] The present invention uses a trapezoidal microstrip guide and a dielectric-filled waveguide to connect the microstrip line and the ultra-thin cavity power divider, which has the advantages of a straight-through transition structure between a waveguide power divider and a microstrip circuit and easy processing, and avoids the main problems of the traditional transition method in engineering applications. The concept of the transition structure and the ultra-thin cavity power divider of the present invention can also be used in other frequency bands or other cavity power dividers.

[0046] The W-band ultra-thin cavity power divider proposed by the present invention is more than 1mm shorter in height than the traditional standard W-band cavity power divider, which reduces the processing difficulty and improves the processing accuracy; and the waveguide-microstrip transition structure proposed by the present invention is shorter in length than the fin line transition and does not require vertical transition compared to the microstrip patch transition, which reduces the overall volume and reduces the processing difficulty. At the same time, the structure of the present invention can be used in the entire W-band circuit, and all circuits from signal input, power division, amplification, combining to signal output can be completed on the same plane.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A W-band microstrip-ultra-thin waveguide power divider-microstrip structure, characterized in that: The structure is mirror-symmetrical on the left and right sides, and includes an ultra-thin waveguide power divider, an input microstrip component arranged at the input end of the ultra-thin waveguide power divider, and two output microstrip components arranged at the output end of the ultra-thin waveguide power divider; The input microstrip assembly and the output microstrip assembly have the same structure, and both include: an air cavity, a dielectric substrate, a metal patch arranged on the front side of the dielectric substrate, and a metal floor covering the back side of the dielectric substrate; The metal patch includes a microstrip line, a trapezoidal gradient conductive strip, and a conductive strip extension section connected in sequence; The other end of the microstrip line is a signal input port or an output port; The upper base of the trapezoidal tapered guide strip is the same as the line width of the microstrip line, and the lower base extends to the ultra-thin waveguide input end or the ultra-thin waveguide output end of the ultra-thin waveguide power divider through the guide strip extension section; The air cavity is located directly above the dielectric substrate, and the surface of the air cavity close to the ultra-thin waveguide power divider is located above the extended section of the guide strip and perpendicular to the extended section of the guide strip, and the distance between the air cavity and the bottom of the trapezoidal gradient guide strip is within the range of 0 to 0.3 mm; The ultra-thin waveguide power divider is T-shaped as a whole, and includes an ultra-thin input waveguide, two ultra-thin output waveguides, and matching grooves located in the same plane; the narrow side dimensions of the ultra-thin input waveguide and the ultra-thin output waveguide are the same as the overall thickness of the input microstrip component and the output microstrip component.

2. A W-band microstrip-ultra-thin waveguide power divider-microstrip structure as claimed in claim 1, characterized in that: The ultra-thin input waveguide comprises a rectangular waveguide section and a trapezoidal gradient section; one end of the rectangular waveguide section is connected to the input microstrip component, and the other end is connected to two ultra-thin output waveguides through a trapezoidal gradient section with gradually increasing width; The two ultra-thin output waveguides are perpendicular to the ultra-thin input waveguide and are arranged in opposite directions, and an inwardly concave isosceles triangle cut corner is arranged between the two ultra-thin output waveguides; The matching groove is located at the vertex of the inwardly concave isosceles triangle cut angle, and the matching groove and the isosceles triangle cut angle together form a funnel-shaped groove.

3. A W-band microstrip-ultra-thin waveguide power divider-microstrip structure as claimed in claim 2, characterized in that: The lower base of the trapezoidal gradient conductive strip is smaller than or equal to the width of the conductive strip extension section; the conductive strip extension section has the same width as the dielectric substrate.

4. A W-band microstrip-ultra-thin waveguide power divider-microstrip structure as claimed in claim 3, characterized in that: The trapezoidal gradient conductive strip is an isosceles trapezoidal metal patch.

5. A W-band microstrip-ultra-thin waveguide power divider-microstrip structure as claimed in claim 4, characterized in that: The width of the dielectric substrate is less than or equal to the wide side size of the ultra-thin input waveguide and the ultra-thin output waveguide.

6. A W-band microstrip-ultra-thin waveguide power divider-microstrip structure as claimed in claim 5, characterized in that: The width of the air cavity is the same as that of the dielectric substrate, and the height is in the range of 0.5 mm to 1.27 mm.

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