A broadband constant amplitude conversion structure from rectangular waveguide to double-terminal stripline

Abstract

The present invention discloses a broadband equal-amplitude conversion structure from a rectangular waveguide to a double-ended stripline, comprising: a rectangular waveguide, a first and a second dielectric substrate laminated together in sequence, a stripline and a floor copper cladding layer processed on the two output ends of each dielectric substrate surface, a prepreg between the dielectric substrates, and a metallized through hole running through each of the dielectric substrates. A first gap without copper cladding is provided at the center of the first floor copper cladding layer, and a tuning patch is provided at the center of the first gap. The central shape of the centrally symmetrical stripline copper cladding layer is a rectangular ring. The area surrounded by the metallized through hole constitutes an equivalent electromagnetic resonant cavity. By providing the gap and the rectangular ring, high-efficiency equal-amplitude conversion of electromagnetic waves from the waveguide to the resonant cavity and then to the double-output stripline can be achieved. The present invention has the advantages of broadband, high efficiency, planarization, low processing cost, etc., and can be applied to relevant scenarios in the millimeter wave frequency band.

Description

Technical Field

[0001] The invention relates to the field of microwave devices, and in particular to a broadband equal-amplitude conversion structure from a rectangular waveguide to a double-ended stripline. Background Art

[0002] Metal waveguide and stripline are two commonly used transmission line structures in the microwave field. Metal waveguide is completely surrounded by metal walls on all sides. It has the advantages of clear field mode, low loss, and no radiation loss. It is widely used in long-distance microwave transmission systems. The stripline structure is generally manufactured using printed circuit technology (PCB). It consists of two upper and lower metal floors and a rectangular conductor between the two. It has the advantages of small size, light weight, simple process, and low cost. It is widely used in scenarios that require low weight and planarization. Many more complex microwave circuits need to combine the advantages of both, so it is necessary to apply a high-efficiency conversion structure from metal waveguide to stripline.

[0003] Modern communication systems have increasingly higher requirements for bandwidth, so broadband characteristics are an important indicator of conversion structures. On the other hand, for large millimeter-wave antenna arrays, placing the feed port at the center of the array is conducive to shortening the overall length of the transmission line, thereby reducing transmission losses and improving the efficiency of the overall system. Compared with the stripline conversion structure from waveguide to a single output port, the double-ended conversion structure is symmetrical and can be easily placed in the center of the array.

[0004] Based on the above background, a broadband equal-amplitude conversion structure from rectangular waveguide to double-ended stripline is needed in practical applications to meet the demand for broadband and high-efficiency electromagnetic wave conversion from rectangular waveguide to stripline in complex microwave occasions. Summary of the invention

[0005] The object of the present invention is to provide a broadband, high-efficiency, planar, low-cost, broadband equal-amplitude conversion structure from rectangular waveguide to double-ended stripline.

[0006] In order to achieve the above object, the present invention adopts the following technical solution.

[0007] A broadband equal-amplitude conversion structure from a rectangular waveguide to a double-ended stripline comprises: a rectangular waveguide, a first dielectric substrate and a second dielectric substrate laminated together in sequence, and a plurality of metallized through holes penetrating each of the dielectric substrates, wherein the rectangular waveguide is connected to the first dielectric substrate; characterized in that a first copper-clad floor is provided on the lower surface of the first dielectric substrate, a stripline copper-clad layer with two output ends is provided on the lower surface of the second dielectric substrate, a second copper-clad floor is provided on the upper surface of the second dielectric substrate, the first copper-clad floor, the second copper-clad floor and each of the metallized through holes form a resonant cavity; the stripline copper-clad layer comprises a rectangular ring and a rectangular strip extending from the rectangular ring to the output ends on both sides, and the rectangular ring is located in the resonant cavity.

[0008] More preferably, the rectangular waveguide is fixed to the bottom of the first dielectric substrate and is in contact with the first copper-clad layer floor.

[0009] More preferably, a first slot without copper cladding is provided at the center of the first copper cladding layer, and a tuning patch is provided at the center of the first slot; the first slot and the tuning patch are located at the center of the rectangular waveguide. The first slot can couple electromagnetic energy from the feeding rectangular waveguide to the resonant cavity, thereby achieving high-efficiency conversion.

[0010] More preferably, each of the metallized through holes forms a ring structure, and the ring structure is concentrically arranged with the first dielectric substrate.

[0011] More preferably, the electrical connections of each of the metallized through-holes with the first copper-clad bottom plate and the second copper-clad bottom plate are spaced apart from the rectangular ring.

[0012] More preferably, the adjacent distance between the metallized through holes does not exceed 1 / 2 of the medium wavelength.

[0013] More preferably, the stripline copper clad layer is symmetrical about the center to achieve equal amplitude power distribution at the two output ends.

[0014] More preferably, the broadband constant amplitude conversion structure from rectangular waveguide to double-ended stripline is applied in the millimeter wave frequency band.

[0015] More preferably, the broadband constant amplitude conversion structure from rectangular waveguide to double-ended stripline operates in a frequency band of 22 to 32 GHz.

[0016] The beneficial effects that can be achieved by the present invention using the above technical solution are:

[0017] 1. The stripline copper clad layer is composed of a rectangular ring and rectangular strips extending from the rectangular ring to the output ends on both sides, and the rectangular ring is placed in the resonant cavity, which not only realizes the energy coupling from the resonant cavity energy to the stripline copper clad layer, but also the setting of the rectangular ring can greatly expand the bandwidth of the conversion structure, realizing the broadband and high efficiency of the waveguide to double-ended stripline conversion structure, which is suitable for various millimeter wave frequency bands; in addition, the conversion structure can use low-cost PCB technology, is easy to mass produce, and is easy to planarize.

[0018] 2. The present invention can be widely used in various occasions requiring dual-output stripline conversion, such as large array antenna design, equal-amplitude power divider, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Shown is a schematic diagram of the overall structure of an embodiment of the conversion structure provided by the present invention.

[0020] Figure 2 Shown is a side schematic diagram of the conversion structure provided by the present invention.

[0021] Figure 3 Shown is a schematic diagram of the first copper-clad floor.

[0022] Figure 4 The above is a schematic diagram of a stripline copper clad layer.

[0023] Figure 5 Shown is a schematic diagram of the second copper-clad floor.

[0024] Figure 6 FIG. 1 is a graph showing a return loss frequency curve of a conversion structure provided by an embodiment of the present invention.

[0025] Figure 7 Shown is a conversion amplitude frequency curve diagram of two output ports of a conversion structure provided by an embodiment of the present invention.

[0026] Figure 8 Shown is a conversion phase frequency curve diagram of two output ports of a conversion structure provided by an embodiment of the present invention.

[0027] Description of reference numerals:

[0028] 1: rectangular waveguide, 2: first copper-clad floor, 3: stripline copper-clad floor, 4: second copper-clad floor, 5: metallized through hole, 601: first dielectric substrate, 602: second dielectric substrate, 611: adhesive prepreg;

[0029] 201: first gap, 202: tuning patch, 301: rectangular ring copper layer. DETAILED DESCRIPTION

[0030] In the description of the present invention, it should be noted that directional words, such as the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating directions and positional relationships are based on the directions or positional relationships shown in the accompanying drawings, which are only for the convenience of narrating the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and cannot be understood as limiting the specific scope of protection of the present invention.

[0031] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features. Therefore, the definition of "first" and "second" features can explicitly or implicitly include one or more of the features. In the description of the present invention, "at least" means one or more, unless otherwise clearly and specifically defined.

[0032] In the present invention, unless otherwise specified and limited, the terms "assemble", "connect", and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can also be a mechanical connection; it can be directly connected, or it can be connected through an intermediate medium, or the two elements can be internally connected. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] In the invention, unless otherwise specified and limited, a first feature being “above” or “below” a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being “above”, “below”, and “above” a second feature includes that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “above”, “below”, and “below” a second feature includes that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0034] The following is a further description of the specific implementation of the present invention in conjunction with the drawings of the specification, so that the technical solution and its beneficial effects of the present invention are clearer and more explicit. The following description of the embodiments with reference to the drawings is exemplary and intended to explain the present invention, but cannot be understood as limiting the present invention.

[0035] Additional aspects and advantages of the present invention will become apparent from the following description or may be learned by practice of the present invention.

[0036] like Figure 1 , Figure 2 As shown, a broadband equal-amplitude conversion structure from a rectangular waveguide to a double-ended stripline includes: a rectangular waveguide 1, a first dielectric substrate 601 and a second dielectric substrate 602 laminated together in sequence, a prepreg 611 pasted between the dielectric substrates, and a metallized through hole 5 penetrating each of the dielectric substrates; a first copper-clad floor 2 is provided on the lower surface of the first dielectric substrate 601, a stripline copper-clad layer 3 at two output ends is provided on the lower surface of the second dielectric substrate 602, and a second copper-clad floor 4 is provided on the upper surface of the second dielectric substrate 602; the rectangular waveguide 1 is fixed to the bottom of the first dielectric substrate 601 and contacts the first copper-clad floor 2.

[0037] The specific structure of the first copper-clad floor panel 2 and the second copper-clad floor panel 4 is that the copper-clad layer covers the entire corresponding surface of the dielectric substrate except for the corresponding gaps.

[0038] The first dielectric substrate 601 and the second dielectric substrate 602 serve as carriers of the copper-clad layers, and the upper and lower surfaces of each dielectric substrate can be processed with copper-clad layers. In order to make the dielectric substrates 601 and 602 stick together, a prepreg 611 is added between the two dielectric substrates for lamination.

[0039] The metallized through holes 5 are distributed around the center of the structure, passing through each of the dielectric substrates, and realizing the electrical connection of the copper-clad floor panels 2 and 4. The metallized through holes 5 are spaced a certain distance from the stripline copper-clad layer 3 and are not electrically connected. The metallized through holes 5 can limit the lateral diffusion of electromagnetic waves within its range, and the enclosed area together with the first and second copper-clad floor panels 2 and 4 constitute an equivalent electromagnetic resonant cavity. In order to improve the resonance efficiency, the distance between adjacent metallized through holes generally does not exceed 1 / 2 of the dielectric wavelength.

[0040] Combination Figure 3 As shown, a first rectangular slit 201 without copper cladding is provided at the center of the first copper cladding layer 2, and a rectangular tuning patch 202 is provided at the center of the first slit 201. The first slit 201 without copper cladding is etched at the center of the first copper cladding metal layer 2 and is located at the center of the contact surface between the feeding waveguide 1 and the first dielectric substrate 601. The first slit 201 can couple electromagnetic energy from the feeding rectangular waveguide to the resonant cavity.

[0041] Combination Figure 4 As shown, the stripline copper clad layer 3 is composed of a rectangular ring 301 at the center of the structure and a long rectangular strip extending to the two output ends. The stripline copper clad layer 3 is symmetrical about the center, thereby achieving equal amplitude power distribution at the two output ends. The rectangular ring 301 is located in the resonant cavity, so that the resonant cavity energy is coupled to the stripline copper clad layer, thereby achieving the conversion of electromagnetic energy to the stripline. And the use of this rectangular ring can greatly expand the bandwidth of the conversion structure.

[0042] Combination Figure 5 As shown, the second copper-clad floor panel 4 completely covers the upper surface of the second dielectric substrate 602 .

[0043] The influence of each structure on the antenna performance is as follows: by adjusting the position of the metallized through hole 5, the size of the stripline rectangular ring 301 and the rectangular gap 201, the resonant frequency and bandwidth can be adjusted; by adjusting the position of the metallized through hole 5, the size of the stripline rectangular ring 301 and the tuning patch 202, the matching of the conversion structure can be adjusted. By selecting appropriate size parameters and the material and thickness of the dielectric plate, broadband conversion structure performance can be achieved. As for the specific size design, it is the common technical knowledge mastered by those skilled in the art and can be matched through routine experiments.

[0044] According to one embodiment of the present application, a broadband equal-amplitude conversion structure from a rectangular waveguide to a double-ended stripline is designed to operate in the 27 GHz frequency band. The rectangular waveguide 1 is selected as the standard rectangular waveguide BJ260. Dielectrics 601 to 602 are all selected from dielectric substrates with a relative dielectric constant of 3.0, a loss tangent of 0.003, a thickness of 0.529 mm, and the area of ​​the dielectric plates is 15 mm × 15 mm. There is a 0.1 mm thick semi-cured sheet 611 between adjacent dielectric plates for lamination. The width of the stripline 3 at the two output ends is selected to be 0.7 mm, the size of the rectangular gap 201 is 6.9 mm × 3.5 mm, and the size of the tuning patch 202 is 4.1 mm × 2.0 mm. The outer contour size of the rectangular ring 301 is 4.3 mm × 1.1 mm, and the width of the copper cladding of the ring is 0.4 mm. The diameter of the metallized through hole 5 is 0.5 mm, the distance between adjacent through holes is 1 mm, the vertical distance between two rows of transverse through holes along the strip line direction is 4.8 mm, and the horizontal distance between two rows of longitudinal through holes is 9.1 mm.

[0045] The effect of the present invention can be further illustrated by the simulation results of this embodiment.

[0046] like Figure 6 As shown, it is a frequency curve of the return loss S11 obtained in the above embodiment. From the figure, it can be seen that the conversion structure achieves a return loss performance below -10dB between 23 and 31GHz, and the relative bandwidth exceeds 30%, with good broadband matching characteristics.

[0047] like Figure 7As shown in FIG. 1 , it is a frequency curve diagram of the electromagnetic wave conversion amplitudes S21 and S31 of the two stripline output ends relative to the waveguide input end obtained in the above embodiment. From the figure, it can be seen that the antenna achieves an amplitude conversion of more than -3.5dB between 23 and 31GHz, the amplitude loss is within 0.5dB, and the amplitudes of the two output ends are basically consistent. This shows that the structure achieves a high equal amplitude conversion efficiency in a wide frequency band.

[0048] like Figure 8 As shown, it is a frequency curve diagram of the electromagnetic wave conversion phase ∠S21 and ∠S31 of the two stripline output ends relative to the waveguide input end obtained in the above embodiment. From this figure, it can be seen that the electromagnetic wave phase difference of the two stripline output ends of this structure is fixed at about 180 degrees, that is, anti-phase.

[0049] Through the description of the above structure and principle, those skilled in the art should understand that the present invention is not limited to the above specific implementations, and improvements and substitutions based on the present invention using the known technology in the art fall within the protection scope of the present invention, and the protection scope of the present invention should be defined by the claims and their equivalents. Parts not described in the specific implementations are prior art or common knowledge.

Claims

1. A broadband equal-amplitude conversion structure from rectangular waveguide to double-ended stripline. include: A rectangular waveguide, a first dielectric substrate and a second dielectric substrate laminated together in sequence, and a plurality of metallized through holes penetrating each of the dielectric substrates, wherein the rectangular waveguide is connected to the first dielectric substrate; characterized in that a first copper-clad floor is provided on the lower surface of the first dielectric substrate, a stripline copper-clad layer with two output ends is provided on the lower surface of the second dielectric substrate, and a second copper-clad floor is provided on the upper surface of the second dielectric substrate, wherein the first copper-clad floor, the second copper-clad floor and each of the metallized through holes form a resonant cavity; the stripline copper-clad layer comprises a rectangular ring and a rectangular strip extending from the rectangular ring to the output ends on both sides, and the rectangular ring is located in the resonant cavity; The rectangular waveguide is fixed to the bottom of the first dielectric substrate and contacts the first copper-clad floor. A first gap without copper cladding is provided at the center of the first copper-clad floor, and a tuning patch is provided at the center of the first gap. The first gap and the tuning patch are located at the center of the rectangular waveguide. Each of the metallized through holes forms a ring structure, and the ring structure is concentrically arranged with the first dielectric substrate. The electrical connection between each of the metallized through holes and the first copper-clad floor and the second copper-clad floor is separated from the rectangular ring. The adjacent distance between the metallized through holes does not exceed 1 / 2 of the medium wavelength, and the stripline copper cladding layer is symmetrical about the center to achieve equal amplitude power distribution at the two output ends.

2. A broadband equal-amplitude conversion structure from a rectangular waveguide to a double-ended stripline according to claim 1, It is characterized in that Applicable to millimeter wave frequency band.

3. A broadband equal-amplitude conversion structure from rectangular waveguide to double-ended stripline according to claim 2, It is characterized in that Works in the frequency band of 22~32GHz.

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