A broadband probe horn antenna based on a composite x p ridge

Abstract

A broadband probe horn antenna based on a composite xp ridge, comprising a rectangular ridge waveguide structure, an open radiation boundary structure and a composite ridge structure. The rectangular ridge waveguide structure is a double-ridge waveguide, and the open radiation boundary structure is a symmetric flat plate, which are respectively connected to the wide-wall end faces of the rectangular ridge waveguide structure. Two composite ridge structures are respectively arranged on the opposite faces of the open radiation boundary structure and connected to the double-ridge end faces of the rectangular ridge waveguide structure; the two composite ridge structures are symmetric, the plane where the composite ridge structure is located is the yoz plane, taking the center point of the rectangular ridge waveguide structure as the origin of the coordinate axis, and taking the radiation direction of the probe horn antenna, that is, the radiation direction, as the z direction to establish a coordinate system. The opposite sides of the two composite ridge structures are defined as ridge edges, and the ridge edges satisfy continuity in mathematical form, so that the composite ridge structure forms a composite xp ridge, that is, the part of the ridge edge close to the rectangular ridge waveguide structure is an xp curve, and the part far from the rectangular ridge waveguide structure is an arc transition curve.

Description

Technical Field

[0001] The present invention belongs to the technical field of antennas, and relates to a probe horn antenna applied to an antenna far-field test system, and particularly relates to a broadband probe horn antenna based on a composite x p -ridge. Background Art

[0002] In an antenna test system, far-field measurement technology is one of the earliest technologies. The far-field measurement technology measures the corresponding far-field radiation characteristics directly by using a standard probe applying far-field to test an antenna placed at a distance of 2D 2 / λ from the antenna under test (D is the radiation aperture size of the antenna under test, and λ is the operating wavelength of the antenna under test). Therefore, the far-field measurement technology is widely used in the field of antenna measurement.

[0003] As an important part of the far-field measurement system, the performance of the probe horn antenna will directly affect the efficiency of the entire measurement system. The desired probe horn antenna should be able to provide a relatively wide operating bandwidth, have a low voltage standing wave ratio at the same time, be able to provide good symmetry of the radiation pattern and corresponding main lobe characteristics within the operating bandwidth, and improve the operating efficiency of the antenna test system.

[0004] At present, the probe horn antenna loaded with a ridge structure is a common form structure in the far-field measurement system. As early as 2005, scholars such as Botello designed a dual-ridge probe horn antenna operating at 1 GHz to 14 GHz based on an exponential curve structure, but at 12 GHz in the high-frequency band, the radiation pattern appeared saddle-shaped and serious lobing phenomenon occurred; subsequently, Abbas-Azimi et al. loaded an arc structure at the end of the above ridge structure, not only achieving a relatively wide operating bandwidth of 1 GHz to 18 GHz, but also having relatively good radiation characteristics in the high-frequency band. Although the above two studies have broadened the bandwidth of the probe horn antenna, with the rapid development of wireless communication technology nowadays, the research on ultra-wideband antennas has gradually become a hot topic. Especially in fields such as radar detection and electromagnetic compatibility testing, the probe horn antenna is required to have a wider bandwidth characteristic. Summary of the Invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a broadband probe horn antenna based on a composite x p -ridge, mainly solving the problems such as the narrow bandwidth of the existing probe horn antenna and the deterioration of radiation characteristics in the high-frequency band, and improving the test performance of the entire far-field test system from the perspective of improving the overall performance of the probe horn antenna. The designed probe horn antenna has an operating frequency range of 1 GHz to 27 GHz, a voltage standing wave ratio below 2.5, and at the same time realizes stable gain, as well as good directivity and main lobe characteristics of the radiation pattern.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A broadband probe horn antenna based on a composite x p ridge, comprising a rectangular ridge waveguide structure, an open radiation boundary structure and a composite ridge structure. The rectangular ridge waveguide structure is a double-ridge waveguide. The open radiation boundary structure is a symmetric flat plate, which is respectively connected to the wide-wall end faces of the rectangular ridge waveguide structure. Two composite ridge structures are respectively arranged on the opposite faces of the open radiation boundary structure and connected to the double-ridge end faces of the rectangular ridge waveguide structure. The two composite ridge structures are symmetric. The plane where the composite ridge structure is located is the yoz plane. Taking the center point of the rectangular ridge waveguide structure as the coordinate origin of the coordinate axis and the radiation direction of the probe horn antenna, that is, the radiation direction, as the z direction, a coordinate system is established. The opposite sides of the two composite ridge structures are defined as ridge edges, and the ridge edges satisfy formal continuity in mathematics, so that the composite ridge structure forms a composite x p ridge, that is, the part of the ridge edge close to the rectangular ridge waveguide structure is an x p curve, and the part far from the rectangular ridge waveguide structure is an arc transition curve, where p is a constant used to adjust the curvature of the ridge edge near the aperture surface.

[0008] In one embodiment, the composite ridge structure is a flat plate structure. One side of it is connected to the open radiation boundary structure, the bottom side is connected to the double-ridge end face of the rectangular ridge waveguide structure, and the remaining sides are smoothly transitioned and defined as ridge edges. The x p curve and the arc transition curve have the following functional forms:

[0009]

[0010] In the formula, Y(z) represents the x p curve, which is established with the radiation direction z as the independent variable and y as the dependent variable. d represents the ridge spacing of the rectangular ridge waveguide structure. r1 represents half of the radiation end spacing of the two composite ridge structures. r 11 is an adjustment parameter used to adjust the aperture ridge spacing size at the aperture arc transition connection of the composite ridge structure. L represents the length of the x p curve along the radiation direction z. A is a constant used to adjust the curvature of the ridge edge near the feeding end.

[0011] Z(y) represents the arc transition curve, which is established with y as the independent variable and z as the dependent variable. r represents the radius of the circle of the end arc transition structure in the composite ridge structure. Z r represents the abscissa of the center of the end arc transition structure in the composite ridge structure. Y r represents the ordinate of the center of the end arc transition structure in the composite ridge structure.

[0012] Based on the overall structural plane of the composite ridge structure, the larger the A and p values, the more the opposite sides of the two radiating plane ridge structures in the composite ridge structure contract towards the open radiation boundary structure relative to the overall structure, gradually increasing the radiation gap between the plane double-ridge structures and further adjusting the radiation characteristics of the entire antenna, r 11 The larger the r, the relatively smaller the ridge spacing at the aperture of the circular arc transition connection of the composite ridge structure, and the more obvious the curvature of the circular arc transition curve.

[0013] In one embodiment, the composite ridge structure is composed of a rectangular ridge waveguide transition section x p type ridge structure and an aperture transition section composite x p type ridge structure, where the rectangular ridge waveguide transition section x p type ridge structure is connected to the double-ridge end face of the rectangular ridge waveguide structure.

[0014] In one embodiment, a reflection back cavity structure is provided at the short-circuit plate on the inner bottom surface of the rectangular ridge waveguide structure. The reflection back cavity structure is composed of two wedges attached to the narrow walls of the rectangular ridge waveguide structure and four right-angled triangular bodies attached to the wide walls of the rectangular ridge waveguide structure. Each right-angled triangular body has a fixed angle with the short-circuit surface of the rectangular ridge waveguide structure; the two wedges are symmetric about the central cross-section of the wide wall, and a single wedge is symmetric about the central cross-section of the narrow wall; the two right-angled triangular bodies attached to the same wide wall are symmetric about the central cross-section of the wide wall, and the two right-angled triangular bodies clamped on both sides of the same wedge are symmetric about the central cross-section of the narrow wall; rectangular ridges are respectively filled between the two right-angled triangular bodies attached to the same wide wall to form the double ridges of the rectangular ridge waveguide structure, that is, the first ridge structure and the second ridge structure.

[0015] In one embodiment, a fillet transition is provided between the wedge and the right-angled triangular body, and a coaxial ridge waveguide converter structure is provided on the rectangular ridge waveguide structure; the coaxial ridge waveguide converter structure is connected by an SMA connector, and it is composed of a coaxial cable feed connector and a tuning hole. The inner core of the coaxial cable feed connector passes through the through hole of the first ridge structure of the rectangular ridge waveguide structure to form a monopole radiator structure with the second ridge structure. The tuning hole is loaded on the side wall where the first ridge structure is located, and its height dimension is the same as the wall thickness of the rectangular ridge waveguide structure to realize the adjustment of the overall matching characteristics of the probe horn antenna by the tuning hole.

[0016] In one embodiment, the inner core and the through hole satisfy the inner and outer radius ratio to realize the characteristic impedance value of the feed coaxial line varying within a relative range of 45Ω to 55Ω. While ensuring that the through hole does not damage the composite ridge structure, the distance between the inner core of the coaxial probe and the composite ridge structure is between 0.8mm and 1.2mm, which can be used to improve the matching in the working frequency range of 22GHz to 27GHz at high frequencies.

[0017] In one embodiment, the bottom edge length of the open radiation boundary structure is the same as the length of the wide wall of the rectangular ridge waveguide structure, and it extends upward with a fixed opening angle, and its length L2 > 1 / 2λ max , and the top edge width of the open radiation boundary structure is the same as the maximum distance between the two composite ridge structures. The top of the open radiation boundary structure is an arc-shaped structure, where λ max is the wavelength corresponding to the probe antenna operating at the lowest frequency.

[0018] In one embodiment, corrugated slot structures are loaded on two opposite surfaces of the two open radiation boundary structures. The corrugated slot structures are embedded in the open radiation boundary structure in the form of equal depth and equal interval, and are distributed at equal intervals along the axial direction. The axial length of the corrugated slot structure is less than the axial length of the open radiation boundary structure.

[0019] In one embodiment, for the corrugated slot structure, when viewed along the plane where the open radiation boundary structure is located, its inner edge coincides with the edge of the composite ridge structure, and its outer edge coincides with the edge of the open radiation boundary structure. Multiple slots are linearly arranged at equal intervals along the axial direction of the open radiation boundary structure, and when viewed transversely along the open radiation boundary structure, there is a difference factor between the lengths of each slot.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] First, the present invention breaks the conventional exponential ridge curve structure. By adopting a composite x p curve and performing an arc transition composite treatment at the aperture surface of the ridge structure, the diffraction of electromagnetic waves at the aperture of the probe horn antenna is reduced. Through the shaping of the ridge curve, the voltage standing wave ratio of the designed probe horn antenna is below 2.5 within the operating frequency band of 1 GHz to 27 GHz, achieving broadband characteristics.

[0022] Second, the present invention improves the structure at the reflection back cavity of the rectangular ridge waveguide. By reasonably adjusting the structural parameters such as the length, thickness of the symmetric wedge and the width of the wedge embedded in the triangle, the gain of the probe horn antenna is compensated within the frequency range of 18 GHz to 22 GHz, and the gain of the probe horn antenna within the frequency band is 6 dBi to 21 dBi, avoiding the defect that the gain drops suddenly due to the excitation of high-order modes.

[0023] Third, the present invention loads corrugated slot structures on the surface of the open radiation boundary, making the corrugated slots have high impedance characteristics, eliminating the transverse radiation current generated by high-order modes, leaving only the longitudinal component, so that the radiation is mainly concentrated between the double ridge structures, solving the phenomenon such as radiation pattern lobes at high frequencies, thereby improving the directivity and stability of radiation within the operating frequency band. Description of the Drawings

[0024] Figure 1 It is a perspective view of the overall structure of the present invention.

[0025] Figure 2 It is a sectional view of the overall structure of the present invention arranged axially.

[0026] Figure 3 It is the dimension marking of the rectangular ridge waveguide structure of the present invention.

[0027] Figure 4 It is an end view of the rectangular ridge waveguide structure of the present invention.

[0028] Figure 5 It is the overall structure diagram of the coaxial converter of the present invention

[0029] Figure 6 It is the overall structure diagram of the rectangular ridge waveguide reflection back cavity of the present invention.

[0030] Figure 7 It is a sectional view of the internal structure of the rectangular ridge waveguide reflection back cavity of the present invention.

[0031] Figure 8 It is a schematic diagram of the wedge structure of the present invention.

[0032] Figure 9 It is a schematic diagram of the right triangular prism structure of the present invention.

[0033] Figure 10 It is a schematic diagram of the open radiation boundary structure with a corrugated groove structure of the present invention.

[0034] Figure 11 It is a sectional view of the composite ridge structure of the present invention.

[0035] Figure 12 It is a schematic diagram of the voltage standing wave ratio comparison of the present invention.

[0036] Figure 13 It is a schematic diagram of the gain varying with the operating frequency of the present invention.

[0037] Figure 14 It is the radiation pattern in the rectangular coordinate system of the E-plane and H-plane of the present invention at different frequencies. Among them, (a) corresponds to 2 GHz, (b) corresponds to 12 GHz, (c) corresponds to 23 GHz, and (d) corresponds to 27 GHz. Detailed implementation manners

[0038] In order to make the objectives, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but it shall not be used as a basis for any limitation to the present invention.

[0039] The present invention is a kind of based on composite x pA broadband probe horn antenna for the ridge operates in common microwave frequency bands such as L, S, C, X, Ku, and K, and at the same time has good gain, stability of the radiation pattern, and good main lobe characteristics. In the following content of the present invention, for the convenience of description, the antenna aperture end is defined as "above", and the corresponding other end is "below".

[0040] Reference Figure 1 、 Figure 2 and Figure 3 , the present invention mainly includes a rectangular ridge waveguide structure 2, an open radiation boundary structure 4, and a composite ridge structure 6.

[0041] Among them, the rectangular ridge waveguide structure 2 is a double-ridge waveguide, and the open radiation boundary structure 4 is two symmetric flat plates, which are respectively connected to the wide-wall end faces of the rectangular ridge waveguide structure 2. The two composite ridge structures 6 are both flat plate structures, which are respectively arranged on the opposite faces of the open radiation boundary structure 4 and connected to the double-ridge end faces of the rectangular ridge waveguide structure 2. The two composite ridge structures 6 are symmetrically arranged, and their opposite sides are defined as ridge edges. Taking the plane where the two composite ridge structures 6 are located as the yoz plane, the center point of the rectangular ridge waveguide structure 2 as the coordinate axis origin, and the radiation direction, that is, the radiation direction of the probe horn antenna, as the z direction, an xyz space coordinate system is established.

[0042] In the present invention, the composite ridge structure 6 constitutes a composite x p ridge, that is: the part of the ridge edge close to the rectangular ridge waveguide structure 2 is an x p curve, and the part far from the rectangular ridge waveguide structure 2 is an arc transition curve. The two parts are smoothly connected and satisfy continuity in mathematical form. Where p is a constant, which is used to adjust the curvature of the ridge edge near the aperture.

[0043] By endowing the composite ridge structure 6 on the rectangular ridge waveguide structure 2 with curves in the present invention, the composite ridge structure 6 reduces the reflection of the radiated electromagnetic wave between the double ridges and the side radiation boundary through the endowment of the ridge curve, so that the probe horn antenna has a working bandwidth of 1 GHz to 27 GHz.

[0044] Refer to Figure 3 and Figure 4, in an embodiment of the present invention, the dimensions of the wide side a and the narrow side b of the aperture surface of the rectangular ridged waveguide structure 2 are mainly determined by the operating cut-off frequency. Generally, for a common rectangular waveguide operating in the dominant mode, it satisfies a < λc < 2a. The dimension of the narrow side b should be less than or equal to about half of the wide side a. However, due to the loaded ridge structure, the cut-off frequency of the dominant mode is reduced, and the cut-off wavelength of the dominant mode is greater than 2a, thus improving its bandwidth characteristics. Its axial length L1 should be an integer multiple of 1 / 4 of the wavelength corresponding to the operating frequency. In this embodiment, a = 48 mm, b = 29 mm, and L1 = 40 mm. At the same time, during the design and processing, the right-angle structure should be rounded. On the standard that the fillet radius should be greater than 0.2 mm, all the right-angle side walls in the rectangular ridged waveguide structure 2 are set into a fillet transition structure. In this embodiment, the fillet radius is taken as 1 mm. In the figure, d represents the ridge spacing, and w1 is the single-ridge width. In the present invention, the double ridges of the rectangular ridged waveguide structure 2 are defined as the first ridge structure 21 and the second ridge structure 22 respectively.

[0045] Refer to Figure 5 , in an embodiment of the present invention, a coaxial-ridged waveguide converter structure 3 is provided on the rectangular ridged waveguide structure 2. The coaxial-ridged waveguide converter structure 3 is connected by an SMA connector and is composed of a coaxial cable feed-through connector 31 and a tuning hole 32. The inner core 311 of the coaxial cable feed-through connector 31 passes through the through-hole of the first ridge structure 21 of the rectangular ridged waveguide structure 2 and forms a monopole radiator structure with the second ridge structure 22. At the same time, its size d1 / d2 = 2.3. Where d1 is the diameter of the inner core 311 and d2 is the diameter of the tuning hole 32. In the embodiment of the present invention, the inner core 311 and the through-hole satisfy the inner and outer radius ratio to achieve a characteristic impedance of 50 Ω. In this embodiment, d1 = 0.9 mm and d2 = 2.1 mm. The tuning hole 32 is loaded on the side wall where the first ridge structure 21 is located. In order to realize the adjustment of the overall matching characteristics of the probe horn antenna by the tuning hole 32, the height dimension of the tuning hole 32 is the same as the wall thickness of the rectangular ridged waveguide structure 2, which is 3 mm in this embodiment. While ensuring that the through-hole does not damage the composite ridge structure 6, the coaxial probe inner core 311 is 1.2 mm away from the composite ridge structure 6 to improve the matching situation in the working frequency range of 22 GHz to 27 GHz at high frequencies.

[0046] Refer to Figure 6 and Figure 7, in the embodiments of the present invention, a reflection back cavity structure 7 is provided at the short - circuit plate on the inner bottom surface of the rectangular ridged waveguide structure 2. The reflection back cavity structure 7 is composed of two wedges 71 that fit the narrow walls of the rectangular ridged waveguide structure 2 and four right - angled triangular bodies 72 that fit the wide walls of the rectangular ridged waveguide structure 2. Each right - angled triangular body 72 has a fixed angle with the short - circuit surface of the rectangular ridged waveguide structure 2. Among them, the two wedges 71 are symmetric about the central cross - section of the wide wall of the rectangular ridged waveguide structure 2, and a single wedge 71 is symmetric about the central cross - section of the narrow wall of the rectangular ridged waveguide structure 2. The two right - angled triangular bodies 72 that fit the same wide wall are symmetric about the central cross - section of the wide wall of the rectangular ridged waveguide structure 2, and the two right - angled triangular bodies 72 clamped on both sides of the same wedge 71 are symmetric about the central cross - section of the narrow wall of the rectangular ridged waveguide structure 2. Cuboid ridges are filled between the two right - angled triangular bodies 72 that fit the same wide wall to form the double ridges of the rectangular ridged waveguide structure 2, defined as the first ridge structure 21 and the second ridge structure 22, and there is a spacing between the two ridge structures.

[0047] In this embodiment, the reflection back cavity structure 7 has a symmetric wedge shape. The two wedges 71 are distributed along the narrow sides of the rectangular ridged waveguide structure 2, and the four right - angled triangular bodies 72 are distributed along the wide sides of the rectangular ridged waveguide structure 2. In order to avoid the gap defect in the traditional reflection back cavity structure, the symmetric wedge 71 in the reflection back cavity structure 7 is embedded in the right - angled triangular body 72, and there is a fillet transition between the wedge 71 and the right - angled triangular body 72. Combining with the fillet structure, the discontinuous characteristics of the structure in the reflection back cavity are eliminated, and its fillet radius is 1.5 mm.

[0048] Reference Figure 8 , in the embodiments of the present invention, the wedge 71 is a hexahedron structure, having a vertical back surface, a vertical front surface, a horizontal bottom surface, an inclined top surface and two side surfaces. Its vertical back surface has the same shape and area as the narrow wall of the rectangular ridged waveguide structure 2 and fits the narrow wall surface. Its vertical front surface is parallel to the vertical back surface and has an area smaller than that of the vertical back surface. The horizontal bottom surface, the inclined top surface and the two side surfaces are all trapezoids, which are sequentially connected between the vertical front surface and the vertical back surface. The top side of each trapezoid is one side of the vertical front surface, and the bottom side of each trapezoid is one side of the vertical back surface, thus forming a wedge structure similar to a frustum of a pyramid. Exemplarily, the horizontal bottom surface and the inclined top surface are preferably isosceles trapezoids. The horizontal bottom surface contacts the short - circuit plate on the inner bottom surface, and the vertical front surfaces of the two wedges 71 are opposite and have a spacing.

[0049] Reference Figure 9, in the embodiments of the present invention, the main body of the right triangular prism 72 is a right triangular prism structure, which is clamped between the wedge 71 and the wide wall of the rectangular ridge waveguide structure 2. The back side of the right triangular prism structure is attached to the wall surface of the wide wall of the rectangular ridge waveguide structure 2, the bottom side is horizontal, and the other side forms an angle with the waist side of the inclined top surface of the wedge 71. One end face of the right triangular prism structure is attached to the wall surface of the narrow wall of the rectangular ridge waveguide structure 2, and there is a spacing between the other end face and the other end face of the right triangular prism 72 attached to the same wide wall surface. A cuboid ridge is placed at this spacing position. Here, the "end face" refers to the cross-section along the length direction of the triangular prism. "Right angle" means that the cross-section is a right triangle.

[0050] In this embodiment, the reflective back cavity structure 7 mainly plays two roles: First, it adjusts the impedance characteristics corresponding to the reactance value generated by coaxial feeding, thereby adjusting the voltage standing wave ratio characteristics at high frequencies; Second, it suppresses the characteristics of high-order modes, thereby improving the gain characteristics and radiation pattern characteristics by using the back cavity structure. In this embodiment, the wedges 71 are arranged symmetrically, and the height of the symmetric connection end, that is, the length h1 of the vertical edge of the vertical front face, is set to 3 mm. This height value maintains the voltage standing wave ratio in the high-frequency band below 2.5, and the matching is good; In order to improve the radiation characteristics by using the back cavity, a cuboid block with a length of a / 2 = 24 mm, a width of w2 = 5 mm, and a height of h2 = 4 mm is padded between the bottom side of the right triangular prism 72 and the inner bottom short-circuit plate of the rectangular ridge waveguide structure 2, so that the four triangular prisms 72 form an 82° angle with the short-circuit surface structure, improving the current path in the back cavity, thereby suppressing the high-order mode and improving the radiation pattern. In order to eliminate the discontinuous characteristics of the structure in the reflective back cavity and combine with the corresponding rounded corner structure, the radius of the rounded corner is consistent with that inside the rectangular ridge waveguide structure 2, that is, 1 mm.

[0051] Refer to Figure 10 , in an embodiment of the present invention, the bottom edge length of the open radiation boundary structure 4 is the same as the width wall length of the rectangular ridge waveguide structure 2, and it extends upward with a fixed opening angle. According to the broadband characteristics of the probe horn antenna, in order to avoid high-order modes under the broadband characteristics of the probe horn antenna, its length L2 > 1 / 2λ max , and the top edge width of the open radiation boundary structure 4 is the same as the maximum distance between the two composite ridge structures 6, r1 = 70 mm. In addition, in order to eliminate the diffraction of electromagnetic waves at the top edges of the open radiation boundary structure 4, the top of the open radiation boundary structure 4 is designed as an arc structure 41 to eliminate the abrupt change of the structure. For example, its radius R = 30 mm, where λ max is the wavelength corresponding to the lowest frequency at which the probe antenna operates, λ max = 300 mm.

[0052] The open radiation boundary structure 4 adopted in the present invention is one of the technical means to achieve a wide bandwidth. By loading it on the composite ridge structure 6 that plays the main radiation role, the reflection of the radiated electromagnetic wave between the double ridges and the side radiation boundary is reduced. In order to achieve a good transition of the open radiation boundary structure 4 to the radiated electromagnetic wave, the root length thereof is consistent with the wide side of the rectangular ridge waveguide structure 2.

[0053] In an embodiment of the present invention, corrugated groove structures 5 are loaded on two opposite surfaces of the two open radiation boundary structures 4. The corrugated groove structures 5 are embedded in the open radiation boundary structures 4 in the form of equal depth and equal interval, and are distributed at equal intervals along the axial direction. The axial length of the corrugated groove structures 5 is less than the axial length of the open radiation boundary structures 4. The loading of the corrugated groove structures 5 improves the directivity and stability of the high-frequency radiation pattern.

[0054] Further, referring to Figure 10 , a smooth wall with a height of hh = 8 mm is left at the bottom of the open radiation boundary structure 4 for transition, and the thickness also meets the fixation of the overall structure by the processing rivets. Starting from this smooth wall, the corrugated groove structures 5 are arranged upward. Looking along the plane where the open radiation boundary structure 4 is located, the inner edge of the corrugated groove structures 5 coincides with the edge of the composite ridge structure 6, and the outer edge coincides with the edge of the open radiation boundary structure 4. Multiple grooves are linearly arranged at equal intervals along the axial direction of the open radiation boundary structure 4, and looking along the transverse direction (i.e., the x-axis direction in Figure 1 ), there is a difference factor between the lengths of each groove. Exemplarily, its value is set to 2 mm. 70 transverse grooves are opened on each side of the corrugated groove structures 5. The axial length of the corrugated groove structures 5 is 2 / 3L2. The transverse grooves are rectangular grooves. Based on the improvement of the radiation pattern near 18 GHz at high frequencies, taking the center frequency of 10 GHz from 1 GHz to 18 GHz as the standard, the dimensions of the corrugated groove structures 5 are set as follows: the groove width is g = 2.5 mm, the groove depth is h = 8 mm, and the tooth width is t = 0.5 mm.

[0055] In this embodiment, the corrugated groove structures 5 loaded on the open radiation boundary structure 4 play a role in suppressing the radiation of the high-order mode electromagnetic wave at high frequencies, making the main mode radiation concentrated in the double ridge structure, improving the directivity and stability of the radiation patterns in the E-plane and H-plane within the frequency band, and especially avoiding phenomena such as lobes in the radiation pattern. Overall, the probe horn antenna of the present invention applied to far-field testing has wide-band characteristics and maintains good gain bandwidth as well as the main lobe characteristics and directivity of the radiation pattern. In an application example of the present invention, it includes a flange fixing structure 1, a rectangular ridge waveguide structure 2, an open radiation boundary structure 4, corrugated groove structures 5, and a composite ridge structure 6 arranged in sequence from bottom to top, thus constituting a wide-band probe horn antenna loaded with a composite x p ridge H-plane wall corrugated groove structure.

[0056] The composite ridge structure 6 of the present invention has one side connected to the open radiation boundary structure 4, the bottom side connected to the double ridge end face of the rectangular ridge waveguide structure 2, and the remaining sides smoothly transition, namely the ridge edge of the present invention. Figure 11 In one embodiment of the present invention, the composite ridge structure 6 is one of the important structures for realizing the broadband characteristics of the probe horn antenna, breaking the conventional exponential curve form. The ridge structure is divided into two sections: first, the rectangular ridge waveguide transition section x p Type ridge structure 61, second, the mouth surface transition section composite x p The rectangular ridge structure 62, wherein the rectangular ridge waveguide transition section x p The rectangular ridge structure 61 is connected to the double-ridge end surface of the rectangular ridge waveguide structure 2 .

[0057] In this embodiment, x can be expressed as a function. p The curve and arc transition curve are shown as follows:

[0058]

[0059] In the formula, y(z) represents x p The curve is established with the radiation direction z as the independent variable and y as the dependent variable. d represents the ridge spacing of the rectangular ridge waveguide structure 2, r1 represents half of the spacing between the radiation ends of the two composite ridge structures 6, and r 11 is an adjustment parameter for adjusting the size of the mouth surface ridge spacing at the mouth surface arc transition connection of the composite ridge structure 6, and L represents x p The length of the curve along the radiation direction z; A is a constant used to adjust the curvature of the ridge edge close to the feed end.

[0060] To avoid the arc transition structure in the two composite ridge structures 6, the value of the independent variable z cannot be represented by y(z) alone. Therefore, z(y) is used to represent the arc transition curve, with y as the independent variable and z as the dependent variable. r represents the radius of the arc transition structure at the end of the composite ridge structure 6, and Z r The horizontal coordinate of the center of the arc transition structure at the end of the composite ridge structure 6, Y r Represents the ordinate of the center of the last arc transition structure in the composite ridge structure 6.

[0061] Example:

[0062]

[0063]

[0064] Taking the overall structural plane of the composite ridge structure 6 as a reference, in this structure, obviously, the larger the values of A and p, the more the overall structure of the opposite sides of the two radiating plane ridge structures in the composite ridge structure 6 contracts towards the open radiation boundary structure 4, making the radiation gap between the plane double-ridge structures gradually larger, and further adjusting the radiation characteristics of the overall antenna, r 11 The larger r is, the relatively smaller the aperture ridge spacing at the circular arc transition connection of the composite ridge structure 6 is, and the more obvious the curvature of the circular arc transition curve is. In this embodiment, A = 0.7 and p = 3.2.

[0065] In the present invention, in the rectangular ridge waveguide transition section x p In the x-type ridge structure 61, its length L = 150 mm is set, and its main function is to achieve a good transition of the impedance of the rectangular ridge waveguide structure 2; looking along the y-axis, at the aperture transition section, the starting point r1 - r of the composite x p -type ridge structure 62 11 to the end point r1, the size of the aperture circular arc curvature is determined by r 11 In order to avoid the diffraction of electromagnetic waves at the aperture and achieve a relatively wide bandwidth characteristic with low spurious, the circular arc curvature is r 11 = 55 mm.

[0066] The effects of the present invention can be further illustrated by the following simulations:

[0067] As Figure 12 shown, it is a schematic diagram of the voltage standing wave ratio comparison of the broadband probe horn antenna in this embodiment. This figure gives the comparison results of the voltage standing wave ratios of the x p -type ridge structure curve before improvement and the composite x p -type ridge structure curve after improvement. In the range of 2 GHz to 27 GHz, the overall voltage standing wave ratio is less than 2.5. However, in the range of 1 GHz to 2 GHz, the x p -type ridge structure curve before improvement results in poor impedance matching characteristics of the antenna, and the highest voltage standing wave ratio reaches 5; but the composite x p -type ridge structure curve after improvement makes the voltage standing wave ratio at low frequencies below 2.5, thus indicating that the composite ridge structure plays a role in broadening the bandwidth. Due to the impedance discontinuity between the characteristic impedance of the probe horn antenna at the aperture and the air, the voltage standing wave ratio is relatively high at low frequencies. In order to meet the ultra-wideband characteristic, the voltage standing wave ratio index is reduced a little without affecting the radiation characteristics, so that the overall probe horn antenna has a good matching effect.

[0068] As Figure 13As shown, it is the gain curve diagram of the broadband probe horn antenna of this embodiment changing with frequency. In the range of 1 GHz to 27 GHz, the gain is between 6.0 dBi and 21.0 dBi, and there is no phenomenon such as a sudden drop in gain within the entire frequency band. The gain has good stability and a relatively wide gain bandwidth.

[0069] As Figure 14 As shown in a, b, c, and d in the figure, it is the radiation pattern of the broadband probe horn antenna of this embodiment in the rectangular coordinate system. Due to the relatively wide bandwidth, the E-plane and H-plane radiation patterns at 2 GHz, 12 GHz, 23 GHz, and 27 GHz are selected. It can be seen from this that there are no lobes and high side lobes in both the E-plane and H-plane, and the maximum level difference between the main lobe and the side lobe is greater than 10 dBi, meeting the application of the probe horn antenna in the test system.

[0070] In summary, for the probe horn antenna of the present invention, first, the shaping of the ridge structure that plays a major transmission role in the radiation characteristics is improved, breaking the conventional exponential ridge curve and adopting a composite x p curve structure. Through the improvement of the transition of the aperture, the broadband characteristics of the research are realized, achieving the goal of an ultra-wideband antenna; secondly, by improving the reflection back cavity of the probe horn antenna, the wedge is symmetrically embedded in the triangular structure, and the angle between the triangular body and the short circuit surface is adjusted to adjust the current path in the back cavity, realizing the suppression characteristics of the mode of the probe horn antenna, and at the same time adjusting the impedance characteristics at high frequencies; finally, a certain number of corrugated slots are loaded at the open radiation boundary. By changing the impedance characteristics of the corrugated slots, the electromagnetic waves radiated by the higher-order modes are suppressed in the corrugated slots, reducing the dispersion of the field on the radiation surface, making the radiation mainly concentrated between the double ridges, improving defects such as lobes in the radiation pattern, and enhancing the overall radiation directivity and stability of the probe horn antenna. Through the optimization of each structural parameter, a broadband probe horn antenna with good radiation characteristics is finally realized.

[0071] The above has introduced in detail a broadband probe horn antenna based on a composite x p ridge H-plane wall corrugated slot structure, and the principle and implementation method of the present invention are elaborated and realized with a detailed structural design. The description of the above embodiments is only used to help understand the method and its core idea of the present invention. It should be pointed out that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A broadband probe horn antenna based on a composite x p ridge, characterized in that, It includes a rectangular ridged waveguide structure (2), an open radiation boundary structure (4) and a composite ridge structure (6). The rectangular ridged waveguide structure (2) is a double-ridged waveguide. The open radiation boundary structure (4) is a symmetric flat plate, which is respectively connected to the wide-wall end faces of the rectangular ridged waveguide structure (2). Two composite ridge structures (6) are respectively arranged on the opposite faces of the open radiation boundary structure (4) and connected to the double-ridged end faces of the rectangular ridged waveguide structure (2). The two composite ridge structures (6) are symmetric. The plane where the composite ridge structure (6) is located is the yoz plane. Taking the center point of the rectangular ridged waveguide structure (2) as the origin of the coordinate axis and the direction pointed by the radiation of the probe horn antenna as the z direction, a coordinate system is established. The opposite sides of the two composite ridge structures (6) are defined as ridge edges, and the ridge edges satisfy continuity in mathematical form, so that the composite ridge structure (6) forms a composite x p ridge. The part of the ridge edge close to the rectangular ridged waveguide structure (2) is an x p curve, and the part far from the rectangular ridged waveguide structure (2) is an arc transition curve, where p is a constant used to adjust the curvature of the ridge edge near the aperture surface; The composite ridge structure (6) is a flat plate structure, one side of which is connected to the open radiation boundary structure (4), the bottom side is connected to the double-ridge end face of the rectangular ridge waveguide structure (2), and the remaining sides are smoothly transitioned, which are defined as ridge edges; the x p The functional forms of the x curve and the arc transition curve are as follows: where y(z) represents x p curve, established with the radiation direction z as the independent variable and y as the dependent variable, d represents the ridge pitch of the rectangular ridge waveguide structure (2), r1 represents half of the radiation end spacing of the two composite ridge structures (6), r 11 is an adjustment parameter for adjusting the aperture ridge pitch size at the aperture arc transition connection of the composite ridge structure (6), L represents x p the length of the curve along the radiation direction z; A is a constant for adjusting the curvature of the ridge edge near the feed end; $z(y)$ represents an arc transition curve, which is established with $y$ as the independent variable and $z$ as the dependent variable. $r$ represents the radius of the circle of the final arc transition structure in the composite ridge structure (6), $Z$ r represents the abscissa of the center of the circle of the final arc transition structure in the composite ridge structure (6), $Y$ r represents the ordinate of the center of the circle of the final arc transition structure in the composite ridge structure (6); Based on the overall structural plane of the composite ridge structure (6), the larger the A and p values are, the more the opposite sides of the two radiating planar ridge structures in the composite ridge structure (6) contract towards the open radiation boundary structure (4) with respect to the overall structure, making the radiation gap between the planar double-ridge structures gradually increase, and r 11 the larger it is, the relatively smaller the ridge pitch at the mouth surface of the mouth surface arc transition connection of the composite ridge structure (6) is, and the more obvious the curvature of the arc transition curve is.

2. The broadband probe horn antenna based on a composite x p ridge according to claim 1, characterized in that, r, Z r and Y r The expressions for are:

3. The broadband probe horn antenna based on a composite x p ridge according to claim 1, characterized in that, A reflection back cavity structure (7) is provided at the short - circuit plate on the inner bottom surface of the rectangular ridge waveguide structure (2). The reflection back cavity structure (7) is composed of two wedges (71) that fit against the narrow walls of the rectangular ridge waveguide structure (2) and four right - angled triangular bodies (72) that fit against the wide walls of the rectangular ridge waveguide structure (2). Each right - angled triangular body (72) has a fixed angle with the short - circuit surface of the rectangular ridge waveguide structure (2); the two wedges (71) are symmetric about the central cross - section of the wide wall, and a single wedge (71) is symmetric about the central cross - section of the narrow wall; the two right - angled triangular bodies (72) that fit against the same wide wall are symmetric about the central cross - section of the wide wall, and the two right - angled triangular bodies (72) clamped on both sides of the same wedge (71) are symmetric about the central cross - section of the narrow wall; rectangular ridges are filled between the two right - angled triangular bodies (72) that fit against the same wide wall to form the double ridges of the rectangular ridge waveguide structure (2), namely the first ridge structure (21) and the second ridge structure (22).

4. The broadband probe horn antenna based on a composite x p ridge according to claim 3, characterized in that, The wedge (71) is a hexahedron structure, having a vertical back surface, a vertical front surface, a horizontal bottom surface, an inclined top surface, and two side surfaces. Its vertical back surface has the same shape and area as the narrow wall of the rectangular ridge waveguide structure (2) and fits against the narrow - wall surface; its vertical front surface is parallel to the vertical back surface and has an area smaller than that of the vertical back surface; the horizontal bottom surface, the inclined top surface, and the two side surfaces are all trapezoids, which are sequentially connected between the vertical front surface and the vertical back surface. The top side of each trapezoid is one side of the vertical front surface, and the bottom side of each trapezoid is one side of the vertical back surface, thus forming a wedge structure; the horizontal bottom surface contacts the short - circuit plate on the inner bottom surface, and the vertical front surfaces of the two wedges (71) face each other and have a spacing; The main body of the right - angled triangular body (72) is a right - angled triangular prism structure, which is clamped between the wedge (71) and the wide wall of the rectangular ridge waveguide structure (2); the back side of the right - angled triangular prism structure fits against the wide - wall surface of the rectangular ridge waveguide structure (2), the bottom side is horizontal, and the other side forms an angle with the waist side of the inclined top surface of the wedge (71). One end face of the right - angled triangular prism structure fits against the narrow - wall surface of the rectangular ridge waveguide structure (2), and there is a spacing between the other end face and the other end face of the right - angled triangular body (72) that fits against the same wide - wall surface. This spacing position is used to place the rectangular ridge.

5. The broadband probe horn antenna based on a composite x p ridge according to claim 4, characterized in that, The transition between the wedge (71) and the right - angled triangular body (72) is in a rounded - corner shape. A coaxial ridge waveguide converter structure (3) is provided on the rectangular ridge waveguide structure (2); the coaxial ridge waveguide converter structure (3) is connected by an SMA connector and is composed of a coaxial cable feed - through connector (31) and a tuning hole (32). The inner core (311) of the coaxial cable feed - through connector (31) passes through the through - hole of the first ridge structure (21) of the rectangular ridge waveguide structure (2) and forms a monopole radiator structure with the second ridge structure (22). The tuning hole (32) is loaded on the side wall where the first ridge structure (21) is located, and its height dimension is the same as the wall thickness of the rectangular ridge waveguide structure (2) to realize the adjustment of the overall matching characteristics of the probe horn antenna by the tuning hole (32).

6. The broadband probe horn antenna based on a composite x p ridge according to claim 5, characterized in that, The inner core (311) and the through hole satisfy the inner and outer radius ratio to enable the feeding coaxial line to have a characteristic impedance value varying within a relative range of 45 Ω to 55 Ω. Under the condition of ensuring that the through hole does not damage the composite ridge structure (6), the inner core (311) of the coaxial probe is spaced 0.8 mm to 1.2 mm from the composite ridge structure (6), which is used to improve the matching condition within the operating frequency range of 22 GHz to 27 GHz at high frequencies.

7. The broadband probe horn antenna based on a composite x p ridge according to claim 1, characterized in that, The bottom side length of the open radiation boundary structure (4) is the same as the width of the wide wall of the rectangular ridge waveguide structure (2), and it extends upward with a fixed opening angle, and its length L2 > 1 / 2λ max , and the top side width of the open radiation boundary structure (4) is the same as the maximum distance between the two composite ridge structures (6). The top of the open radiation boundary structure (4) is an arc structure (41), where λ max is the wavelength corresponding to the probe antenna operating at the lowest frequency.

8. The broadband probe horn antenna based on a composite x p ridge according to claim 1, characterized in that, Corrugated groove structures (5) are loaded on two opposite surfaces of the two open radiation boundary structures (4). The corrugated groove structures (5) are embedded in the open radiation boundary structures (4) in the form of equal depth and equal interval, and are distributed at equal intervals along the axial direction. The axial length of the corrugated groove structures (5) is less than the axial length of the open radiation boundary structures (4).

9. The broadband probe horn antenna based on a composite x p ridge according to claim 8, characterized in that, For the corrugated groove structure (5), when viewed along the plane where the open radiation boundary structure (4) is located, its inner edge coincides with the edge of the composite ridge structure (6), and its outer edge coincides with the edge of the open radiation boundary structure (4). A plurality of grooves are linearly arranged at equal intervals along the axial direction of the open radiation boundary structure (4), and when viewed transversely along the open radiation boundary structure (4), there is a difference factor between the lengths of each of its grooves.

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