Micro-coaxial ultra-wideband Vivaldi antenna and half-mode Vivaldi antenna

Abstract

The invention discloses a micro coaxial ultra wide band Vivaldi antenna and a half mode Vivaldi antenna. The micro coaxial ultra wide band Vivaldi antenna comprises a coaxial feed structure, a fan-shaped feed source and a metal cavity, the coaxial feed structure comprises a coaxial inner core and a coaxial outer conductor, the coaxial inner core is suspended in the coaxial outer conductor, one end of the coaxial inner core is connected with the fan-shaped feed source through a coaxial matching section, and the other end of the coaxial inner core is a free end; the fan-shaped feed source is suspended in the metal cavity, a matching round hole is formed in the metal cavity on one side of the fan-shaped feed source, an exponential gradual change type curve opening is formed in the metal cavity, and the matching round hole is connected with the exponential gradual change type curve opening through an inclined linear gap; comb-shaped gaps are formed in the two sides of the metal cavity; the metal cavity is connected with the coaxial outer conductor; according to the Vivaldi antenna, the antenna loss is reduced through the coaxial structure, the antenna can work at high frequency, the Vivaldi antenna can realize wider impedance matching through the exponential gradual change type curve opening, the comb-shaped gap and the matching round hole, the bandwidth of the Vivaldi antenna is increased, and good gain is kept.

Description

Technical Field

[0001] The present invention relates to the field of antenna technology, and in particular to a micro-coaxial ultra-wideband Vivaldi antenna and a half-mode Vivaldi antenna. Background Art

[0002] Ultra-wideband (UWB) antennas, a key technology in modern wireless systems, leverage nanosecond-level time-domain pulse signal processing capabilities and gigahertz-level operating bandwidth to achieve high-precision positioning while exhibiting superior multipath interference mitigation. Their low power spectral density enables spectrum coexistence with other communication standards (such as Wi-Fi and Bluetooth) in dense electromagnetic environments. This technological advantage has attracted significant attention in applications such as radar detection, short-range communications (such as 5G / 6G), and medical imaging.

[0003] Among the many UWB antenna configurations, the Vivaldi antenna achieves a smooth transition of electromagnetic waves from quasi-static fields to free-space waves through its unique exponentially tapered slotline structure. This gradient discontinuity design not only ensures the antenna's ultra-wideband impedance matching, but its tapered horn-shaped radiation port at the end also gives the antenna a higher gain. Research has shown that the operating bandwidth can be further expanded by introducing elliptical arc slotline correction or composite dielectric loading technology. The reconfigurable nature of this structure gives it unique advantages in phased array radar beamforming and millimeter wave MIMO systems. It is worth noting that breakthroughs in flexible substrate materials and 3D printing manufacturing processes in recent years have further promoted the innovative application of this type of antenna in wearable medical sensors and curved conformal radars.

[0004] The patent with publication number CN105206937A provides a micro-coaxial vivaldi ultra-wideband antenna, which includes a microwave substrate, a metal radiating surface is provided on the front section of the top of the microwave substrate, and the microwave substrate and the metal radiating surface constitute an antenna radiating unit. The front end of the metal radiating surface is provided with a radiation opening with a specific curvature in the metal radiating surface, and the rear section of the microwave substrate behind the metal radiating surface is etched with a shaped groove, The inner conductor is provided with a matching strip shape in the slot. The front end of the lower side of the shape is horizontally forward and exceeds the front end of the upper side, and the inner conductor The upper and lower front ends are connected with inclined transition structures, and the inner conductor The upper side of the shape is connected to the bottom of the rear end of the metal radiation surface through a transition structure, and the inner conductor A photoresist pillar supports the inner wall of the micro-shaped structure and the microwave substrate. The structure also includes an outer conductor that is sheathed around the inner conductor. A photoresist pillar also supports the inner wall of the outer conductor and the inner conductor. An antenna slot is provided at the rear end of the outer conductor. The inner conductor, outer conductor, photoresist pillar, and transition structure form a micro-coaxial feeding unit. A microwave circuit unit is also provided on the bottom surface of the microwave substrate. The microwave circuit unit consists of a microwave chip and a microstrip line. The input and output ends of the microwave chip are connected to the transition structure at the front end of the lower side of the inner conductor via the microstrip line. The ground of the microwave chip is connected to the outer conductor. The microwave substrate serves as the medium for the ultra-wideband Vivaldi antenna, acting as a carrier for the micro-coaxial and microwave chips. The ultra-wideband Vivaldi antenna is a planar printed antenna. The antenna radiation pattern is designed, processed, and gold-plated on one side of the microwave plate to achieve ultra-wideband radiation characteristics of 2-24 GHz. Microwave signals are introduced via slot lines and are directly fed through the micro-coaxial inner conductor, realizing the Vivaldi ultra-wideband feeding structure. Although the Vivaldi antenna disclosed in this patent uses a micro-coaxial structure to realize its basic functions, giving the antenna ultra-wideband characteristics, the antenna's maximum operating frequency is 24GHz, which has not yet reached the millimeter wave band and cannot expand the antenna's application scenarios.

[0005] The patent with publication number CN117728155A provides a 2-70GHz ultra-wideband, all-metal Vivaldi antenna, including a metal plate, a supporting base plate configured at the bottom end of the metal plate, a coaxial connector passing through the supporting base plate and connected to the metal plate, an exponential gradient curve opening is provided on the inner side of the upper part of the metal plate, a matching circle is provided at the lower part of the metal plate, an inclined groove is provided on the metal plate between the exponential gradient curve opening and the matching circle, the starting end of the exponential gradient curve opening is connected to one end of the inclined groove, and the other end of the inclined groove is connected to the matching circle, and the inner conductor of the coaxial connector is in contact with the upper surface of the end where the inclined groove and the matching circle are connected; traditional Vivaldi antennas rarely operate at frequencies of 40GHz and above. By optimizing the thickness of the Vivaldi metal plate, the antenna sample operates at a frequency greater than 70GHz and its return loss exceeds 10dB. The Vivaldi antenna disclosed in this patent has a wide enough operating bandwidth and an operating frequency reaching the millimeter wave band, but it is made of all metal, resulting in its loss being smaller than the Vivaldi antenna processed by PCB technology, but still larger than the Vivaldi antenna processed by micro-coaxial technology. Moreover, the overall size and volume of the antenna are large, and the addition of a large metal base plate at the bottom of the antenna is not conducive to the miniaturization of the antenna.

[0006] In millimeter-wave and terahertz frequency band applications, antennas based on micro-coaxial structures demonstrate unique engineering value due to their wide bandwidth and low loss advantages. The micro-coaxial structure uses an air cavity or a low-dielectric-constant composite material as the supporting medium between the inner coaxial and outer conductors, significantly reducing the ohmic loss and dielectric dispersion effect under high-frequency conditions. Its radiation efficiency can be greatly improved compared to traditional microstrip structures. Thanks to the quasi-TEM wave propagation characteristics and characteristic impedance stability, this type of antenna has excellent high-order mode suppression capabilities while maintaining an ultra-wide impedance bandwidth, making it particularly suitable for multi-band converged communication systems. From a manufacturing perspective, micro-coaxial antennas can be integrated with three-dimensional stacking through photolithography processes. Their compatibility not only simplifies antenna design, but also reduces costs through modular manufacturing.

[0007] Therefore, there is an urgent need to propose a 10-100 GHz frequency band Vivaldi antenna with simple structure, miniaturization, ultra-wideband, low loss and high radiation efficiency. Summary of the Invention

[0008] The object of the present invention is to provide a micro-coaxial ultra-wideband Vivaldi antenna and a half-mode Vivaldi antenna to solve one or more of the above-mentioned technical problems. The present invention provides a micro-coaxial ultra-wideband Vivaldi antenna and a half-mode Vivaldi antenna, which have the characteristics of miniaturization, large bandwidth, high gain, and simple structure. They can be widely used in various microwave systems, especially in radar, satellite and other fields.

[0009] To achieve the above objectives, on the one hand, the present invention provides a micro-coaxial ultra-wideband Vivaldi antenna, comprising a coaxial feeding structure, a sector feed source, and a metal cavity; the coaxial feeding structure comprises a coaxial inner core and a coaxial outer conductor, the coaxial inner core being suspended inside the coaxial outer conductor, one end of the coaxial inner core being connected to the sector feed source via a coaxial matching section, and the other end being a free end; the sector feed source being suspended in the metal cavity, a matching circular hole being provided on the metal cavity on one side of the sector feed source, an exponentially tapered curve opening being provided in the metal cavity, the matching circular hole and the exponentially tapered curve opening being connected via an inclined straight line gap; comb-shaped gaps being provided on both sides of the metal cavity; and the metal cavity being connected to the coaxial outer conductor.

[0010] Furthermore, a plurality of SU-8 support structures are arranged in the coaxial feeding structure at intervals along the axial direction, the SU-8 support structures simultaneously connect the coaxial inner core and the coaxial outer conductor, and the SU-8 support structures use a negative photoresist based on epoxy resin; release holes are arranged around the coaxial outer conductor of the coaxial feeding structure, the release holes are arranged symmetrically about the axis of the coaxial feeding structure, and the cross-section of the release holes is rectangular.

[0011] Furthermore, the width of the exponential gradient curve opening at the starting end is 0.399 mm, the width at the ending end is 5.488 mm, and the distance between the starting end and the ending end is 7.949 mm.

[0012] Furthermore, the other end of the coaxial inner core is connected to the coaxial connector through a coaxial matching interface, and the coaxial matching interface matches the standard connector. At the coaxial matching interface, a cylindrical protrusion is set on one side of the coaxial inner core, and a semicircular notch is set on the coaxial outer conductor corresponding to the side where the cylindrical protrusion is set.

[0013] Furthermore, the coaxial inner core and coaxial outer conductor, the fan-shaped feed source and the metal cavity of the coaxial feeding structure are all made of copper. The thickness of the coaxial outer conductor and the metal cavity is 0.9 mm, and the thickness of the coaxial inner core and the fan-shaped feed source is 0.3 mm.

[0014] Furthermore, the width of the inclined straight line gap is equal to the width of the starting end of the exponential gradient curve opening.

[0015] Furthermore, the metal cavity is a rectangular parallelepiped cavity with a length of 11.65 mm and a width of 14.90 mm, and the radius of the matching circular hole is 0.84 mm.

[0016] Furthermore, the width of the coaxial matching section is smaller than the width of the coaxial core, the coaxial matching section is located as a whole in the metal cavity, the coaxial matching section extends into the fan-shaped feed source by a set length, and the coaxial matching section and the fan-shaped feed source are integrally formed, and the fan-shaped angle of the fan-shaped feed source is 90°.

[0017] Furthermore, the comb-shaped gap is symmetrical about the center line of the metal cavity, and the length of the comb-shaped gap gradually shortens from the fan-shaped feed source to the opening end of the metal cavity.

[0018] On the other hand, the present invention also provides a micro-coaxial ultra-wideband half-mode Vivaldi antenna. Based on the above micro-coaxial ultra-wideband Vivaldi antenna, the side of the metal cavity without the matching circular hole is removed, and the side without the metal cavity is set as a grid.

[0019] Compared with the prior art, the present invention has the following beneficial effects: The exponentially tapered opening and comb-shaped slots increase the bandwidth of the micro-coaxial ultra-wideband Vivaldi antenna while maintaining high gain. The exponentially tapered opening achieves a smooth transition from the feed point to the radiating opening, reducing reflections and ensuring impedance matching across a wide bandwidth. Electromagnetic waves gradually radiate into free space along the exponentially tapered opening, forming end-fire radiation with high gain. The exponential taper provides continuous phase variation and supports resonance at multiple frequencies, thus enabling ultra-wideband operation. The micro-coaxial ultra-wideband Vivaldi antenna of the present invention has a 10-fold operating bandwidth and an impedance bandwidth of about 163.64% (S 11The antenna gain is 4.0dB (-10dB or less) at 10GHz to 100GHz, with a gain of 5.8dB at 10GHz, 7.5dB at 20GHz, 8.2dB at 30GHz, 40GHz, 50GHz, 60GHz, 70GHz, 80GHz, 90GHz, and 1000GHz, respectively. The nine-layer micro-coaxial ultra-wideband Vivaldi antenna, manufactured using the M-MAM (micro metal additive manufacturing) process, offers a simpler structure, lower loss, and wider bandwidth than conventional microstrip antennas and substrate-integrated waveguide antennas.

[0020] Furthermore, the axially periodically arranged SU-8 support structure creates a quasi-rigid mechanical framework, preventing the metal coaxial core from shifting or deforming due to temperature or humidity changes, mechanical vibration, or other external forces, ensuring that the coaxial core can be processed according to the desired structure. SU-8, a high-aspect-ratio photoresist material with a good elastic modulus and low creep properties, effectively disperses the nonlinear stresses induced by thermomechanical loads, ensuring sufficient positioning accuracy between the coaxial core and the coaxial outer conductor. Its electromagnetic properties, with a dielectric constant close to that of air, reduce the field perturbations of the support unit on the transmission line's TEM mode, while suppressing the degradation of the voltage standing wave ratio caused by interface reflections.

[0021] Furthermore, the release holes serve as the etchant diffusion path in the M-MAM process. Their symmetrical design can not only achieve isotropic etching of the polymer matrix, effectively avoiding etching residues caused by the closed cavity, but also significantly reduce the alignment tolerance requirements.

[0022] Furthermore, the thickness of the coaxial inner core and the fan-shaped feed is 0.3 mm, and the wall thickness of the coaxial outer conductor and the metal cavity of the coaxial feed structure is 0.9 mm, which is the standard height for 9-layer micro-coaxial processing. This height can make the electroplating more uniform during processing.

[0023] Furthermore, the overall structure of the micro-coaxial Vivaldi antenna is made of copper, which effectively reduces ohmic losses by utilizing the higher electrical conductivity of copper. By rationally designing the angle of the fan-shaped feed, the additional loss caused by the skin effect can be reduced. At the same time, in high-power scenarios, the thermal diffusion capacity of copper can ensure that the antenna operates within a safe temperature range.

[0024] Furthermore, the coaxial matching interface has a cylindrical metal protrusion above the coaxial inner core, and the micro-coaxial outer conductor above has a semicircular metal notch. This structure can achieve mutual matching between the coaxial feeding structure and the 1mm connector. The width of the coaxial matching section is greater than that of the inner core, forming a stepped impedance transformation structure. The gradual cross-sectional area achieves a smooth transition from the characteristic impedance of the coaxial line to the fan-shaped feed source impedance, thereby reducing interface reflections. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art; obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, without paying any creative work, other drawings can be obtained based on these drawings, such as changing the feeding interface, changing the number of processing layers and layer heights, changing the opening of the exponential gradient curve, changing the radius of the matching circular hole, changing the operating frequency range, changing the size of the metal cavity, etc., which are obvious physical structure and corresponding electrical performance modifications that can be performed by ordinary technicians in this field.

[0026] Figure 1 Schematically shows a three-dimensional structure diagram of a micro-coaxial ultra-wideband Vivaldi antenna according to an embodiment of the present invention; Figure 2 Schematically shows a perspective top view of a micro-coaxial ultra-wideband Vivaldi antenna according to an embodiment of the present invention; Figure 3 Schematically shows a perspective side view of a micro-coaxial ultra-wideband Vivaldi antenna according to an embodiment of the present invention; Figure 4 Schematically shows a three-dimensional structure diagram of a micro-coaxial ultra-wideband half-mode Vivaldi antenna according to an embodiment of the present invention; Figure 5 Schematically shows a perspective top view of a micro-coaxial ultra-wideband half-mode Vivaldi antenna according to an embodiment of the present invention; Figure 6 Schematically shows a perspective side view of a micro-coaxial ultra-wideband half-mode Vivaldi antenna according to an embodiment of the present invention; Figure 7 A graph schematically shows how the return loss of the micro-coaxial ultra-wideband Vivaldi antenna varies with frequency according to an embodiment of the present invention; Figure 8 A graph schematically shows how the return loss of a micro-coaxial ultra-wideband half-mode Vivaldi antenna varies with frequency according to an embodiment of the present invention; Figure 9Schematic diagram of the YOZ radiation pattern of the micro-coaxial ultra-wideband Vivaldi antenna according to an embodiment of the present invention, with frequencies of (a) 10 GHz, (b) 40 GHz, (c) 70 GHz, and (d) 100 GHz, respectively; Figure 10 Schematic diagram of the XOZ radiation pattern of the micro-coaxial ultra-wideband Vivaldi antenna according to an embodiment of the present invention, with frequencies of (a) 10 GHz, (b) 40 GHz, (c) 70 GHz, and (d) 100 GHz, respectively; Figure 11 Schematic diagram of the YOZ plane radiation pattern of the micro-coaxial ultra-wideband half-mode Vivaldi antenna according to an embodiment of the present invention, with frequencies of (a) 10 GHz, (b) 40 GHz, (c) 70 GHz, and (d) 100 GHz respectively; Figure 12 Schematic diagram of the XOZ plane radiation pattern of the micro-coaxial ultra-wideband half-mode Vivaldi antenna according to an embodiment of the present invention, with frequencies of (a) 10 GHz, (b) 40 GHz, (c) 70 GHz, and (d) 100 GHz respectively; Figure 13 A graph schematically shows how the radiation efficiency of a micro-coaxial ultra-wideband Vivaldi antenna according to an embodiment of the present invention varies with frequency; Figure 14 A graph schematically shows how the radiation efficiency of a micro-coaxial ultra-wideband half-mode Vivaldi antenna varies with frequency according to an embodiment of the present invention; Figure 15 A graph schematically shows how the maximum gain of a micro-coaxial ultra-wideband Vivaldi antenna varies with frequency according to an embodiment of the present invention; Figure 16 A graph schematically shows how the maximum gain of a micro-coaxial ultra-wideband half-mode Vivaldi antenna varies with frequency according to an embodiment of the present invention; In the accompanying drawings, 1-coaxial feeding structure, 2-fan-shaped feed source, 3-metal cavity, 4-exponential gradient curve opening, 5-comb-shaped gap, 6-coaxial inner core, 7-coaxial outer conductor, 8-matching circular hole, 9-SU-8 support structure, and 10-release hole. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0028] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way are interchangeable where appropriate so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices. The present invention is described in further detail below in conjunction with the accompanying drawings.

[0029] The embodiment of the present invention discloses a micro-coaxial ultra-wideband Vivaldi antenna and a half-mode Vivaldi antenna, comprising a coaxial feeding structure 1, a sector feed source 2, and a metal cavity 3; an exponential gradient curve opening 4 is provided on the upper part of the metal cavity 3, comb-shaped gaps 5 are provided on both sides of the metal cavity 3, a matching circular hole 8 is provided on the metal cavity 3, and the matching circular hole 8 is provided on one side of the connection between the sector feed source 2 and the coaxial inner core 6; an SU-8 support structure 9 is provided in the metal cavity 3 and the coaxial outer conductor 7, and release holes 10 are uniformly provided on the coaxial outer conductor 7; the coaxial feeding structure 1 comprises a coaxially arranged coaxial conductor. The coaxial inner core 6 and the coaxial outer conductor 7 are suspended within the coaxial outer conductor 7. The coaxial inner core 6 is connected to the sector-shaped feed 2 via a matching structure, the width of which is smaller than that of the coaxial inner core 6. The coaxial inner core 6 is located at the centerline of the coaxial outer conductor 7. The coaxial inner core 6 is connected to the coaxial outer conductor 7 via an SU-8 support structure 9, achieving a suspended arrangement. The sector-shaped feed 2 is suspended within the metal cavity 3 via the SU-8 support structure 9. The release hole 10 is located on the outer wall of the coaxial feed structure 1 and has a rectangular cross-section. The release hole 10 is axially symmetrical about the coaxial inner core 6. The sector-shaped feed 2 can smoothly transition the electromagnetic field distribution between the feeding point and the gap, reducing impedance mutations, reducing reflection losses, and improving energy transmission efficiency. An exponentially tapered curve opening 4 is provided on the upper surface of the metal cavity 3. The exponentially tapered curve opening 4 achieves a smooth transition from the feed point to the radiation opening, reducing reflections and ensuring impedance matching within a wide bandwidth. The exponential gradient provides continuous phase variation, supports resonance at multiple frequencies, and enables ultra-wideband operation of the antenna. Comb-shaped slots 5 are provided on both sides of the metal cavity 3. The comb-shaped slots 5 are symmetrical about the centerline of the metal cavity 3. The comb-shaped slots 5 start from the end of the fan-shaped feed source 2 and gradually shorten in length as they move away from the fan-shaped feed source 2. The comb-shaped slots 5 not only concentrate surface current near the exponentially tapered curve, enhancing radiation, but can also be used to clean photoresist during processing. A matching circular hole 8 is provided at the lower portion of the metal cavity 3. The matching circular hole 8 is connected to the exponentially tapered curve opening 4 by a tilted straight line slot. An arc transition is provided in the matching circular hole 8 to optimize impedance matching, suppress high-frequency reflections, and expand bandwidth.

[0030] refer to Figure 1 and Figure 4 The other end of the coaxial core 6 is connected to the coaxial connector through a coaxial matching interface. The coaxial matching interface matches the standard connector. At the coaxial matching interface, a cylindrical protrusion is set on one side of the coaxial core 6, and a semicircular notch is set on the coaxial outer conductor 7 corresponding to the side where the cylindrical protrusion is set.

[0031] Based on the above structure, the parameters are optimized. The thickness of the SU-8 support structure 9 is h1=0.04mm. The SU-8 support structure 9 is used to support the coaxial core 6, which has little effect on the simulation of the micro-coaxial ultra-wideband Vivaldi antenna; the starting end width of the exponential gradient curve opening 4 is W2=0.399mm, the ending end width is W4=5.488mm, and the distance between the starting end and the ending end is L2=7.949mm. The exponential gradient curve opening 4 is the core of the ultra-wideband performance of the Vivaldi antenna and has a greater impact on the bandwidth during simulation; the radius of the matching circular hole 8 is 0.84mm, and the distance between the matching circular hole 8 and the bottom of the metal cavity 3 is L3=1.715mm, and the distance from the outer wall of the metal cavity 3 closer to the metal cavity 3 is W3=3.928mm. The matching circular hole 8 is mainly used to optimize impedance matching and radiation characteristics.

[0032] In the described micro-coaxial ultra-wideband Vivaldi antenna, the excitation signal is input by the coaxial feed structure 1, transmitted via the coaxial line to the fan-shaped feed source 2, and radiated outward along the exponentially tapered opening 4. The coaxial core 6 has a tapered structure at the junction of the fan-shaped feed source 2 and the coaxial feed structure 1, which is used to achieve broadband impedance matching within the 10-100 GHz range. The use of the exponentially tapered opening 4 and the comb-shaped slots 5 not only improves the bandwidth of the micro-coaxial ultra-wideband Vivaldi antenna, but also maintains sufficient gain.

[0033] To verify the effectiveness of the aforementioned micro-coaxial ultra-wideband Vivaldi antenna and half-mode Vivaldi antenna, the following structural dimensions are used as an example: See also Figures 1 to 6 , Figure 1 A schematic diagram of the three-dimensional structure of a micro-coaxial ultra-wideband Vivaldi antenna according to an embodiment of the present invention is shown schematically; a micro-coaxial ultra-wideband Vivaldi antenna according to an embodiment of the present invention comprises a coaxial feeding structure 1, a fan-shaped feed source 2 and a metal cavity 3, an exponential gradient curve opening 4 is provided at the upper part of the metal cavity 3, comb-shaped gaps 5 are provided on both sides of the metal cavity 3, and a matching circular hole 8 is provided at the lower part of the metal cavity 3. The antenna is manufactured using a nine-layer process, wherein a plurality of SU-8 support structures 9 are located in the fifth layer of the nine-layer micro-coaxial structure, and a plurality of release holes 10 are located on the outer wall of the coaxial feeding structure 1. Figure 2 and Figure 3 A perspective top view and a side view of a micro-coaxial ultra-wideband Vivaldi antenna according to an embodiment of the present invention are schematically shown. In the figure, the thickness of the coaxial core 6 and the fan-shaped feed source 2 is h1=0.3mm, the thickness of the coaxial feeding structure 1 and the metal cavity 3 is H1=0.9mm, the length of the metal cavity 3 is L1=11.65mm, the width is W1=14.90mm, and the height is H1=0.9mm. The fan-shaped feed source 2 is moved 0.151mm toward the coaxial line, and the fan-shaped angle is 90°. Figure 4 Schematically shows a three-dimensional structure diagram of a micro-coaxial ultra-wideband half-mode Vivaldi antenna according to an embodiment of the present invention; Figure 5 and Figure 6 A perspective top view and a side view of a micro-coaxial ultra-wideband half-mode Vivaldi antenna according to an embodiment of the present invention are schematically shown respectively; the length of the metal cavity 3 of the half-mode Vivaldi antenna is L1=11.65mm, and the width is W1 / 2=7.45mm. The side of the metal cavity 3 where the matching circular hole 8 is not provided is removed, and the side where the metal cavity 3 is removed is set as a grid for reinforcing the antenna and promoting more uniform electroplating of the antenna during processing; the comb-shaped gap (5) is symmetrical about the center line of the metal cavity (3), and the length of the comb-shaped gap (5) gradually shortens from the fan-shaped feed source to the open end of the metal cavity 3.

[0034] Figure 7 and Figure 8 The schematic diagram shows the operating frequency bands of the micro-coaxial ultra-wideband half-mode Vivaldi antenna and the half-mode Vivaldi antenna according to an embodiment of the present invention. The return loss of the micro-coaxial ultra-wideband Vivaldi antenna and the half-mode Vivaldi antenna is greater than 10 dB between 10 GHz and 100 GHz.

[0035] Figure 9 、 Figure 10 、 Figure 11 and Figure 12 The YOZ and XOZ radiation patterns of the micro-coaxial ultra-wideband Vivaldi antenna and the half-mode Vivaldi antenna according to the embodiment of the present invention at 10 GHz, 40 GHz, 70 GHz and 100 GHz are schematically shown. Figure 9 、 Figure 10 、 Figure 11 and Figure 12 The figures include four sub-figures (a), (b), (c), and (d), which are the YOZ and XOZ plane radiation patterns at 10 GHz, 40 GHz, 70 GHz, and 100 GHz, respectively. It can be seen from the figures that the antenna's operating frequency band is from 10 to 100 GHz, the antenna bandwidth is about 163.64%, and the antenna gain is better than 4 dB in the entire operating frequency band.

[0036] Figure 13 and Figure 14 The radiation efficiency of the micro-coaxial ultra-wideband half-mode Vivaldi antenna and the half-mode Vivaldi antenna of an embodiment of the present invention is schematically shown. The radiation efficiency of the micro-coaxial ultra-wideband Vivaldi antenna and the half-mode Vivaldi antenna decreases with increasing frequency and is greater than 91% between 10 GHz and 100 GHz.

[0037] Figure 15 and Figure 16The maximum gain of the micro-coaxial ultra-wideband half-mode Vivaldi antenna and the half-mode Vivaldi antenna in an embodiment of the present invention is schematically shown. The maximum gain of the micro-coaxial ultra-wideband Vivaldi antenna and the half-mode Vivaldi antenna is slightly lower at 10-40 GHz. When the frequency is greater than 40 GHz, the maximum gain of the antenna is better than 7 dB.

[0038] In summary, the embodiments of the present invention disclose a micro-coaxial ultra-wideband Vivaldi antenna and a half-mode Vivaldi antenna, which include a coaxial feeding part and a broadband Vivaldi antenna part. Specifically, one end of the coaxial feeding part is connected to a 1 mm connector through a coaxial matching interface, and the other end is connected to the fan-shaped feed source of the Vivaldi antenna. The coaxial inner core of the micro-coaxial structure is located at the center of the coaxial feeding part and is equidistant from the upper and lower metal coaxial outer conductors. The coaxial inner core and the fan-shaped feed source are connected to the coaxial outer conductor through an SU-8 support structure. The release hole is a rectangular release hole and is located on the outer wall of the coaxial feeding structure and is centrally symmetrical about the coaxial inner core. The broadband Vivaldi antenna part includes a rectangular metal cavity and an exponentially tapered curve opening, a comb-shaped gap, and a matching circular hole opened at the bottom of the metal cavity. The present invention reduces the loss of the antenna through a coaxial structure, allowing the antenna to operate at high frequencies, and enables the Vivaldi antenna to achieve wider impedance matching through exponentially tapered curve openings, comb-shaped gaps and matching circular holes, thereby increasing the bandwidth of the Vivaldi antenna and maintaining good gain.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A micro-coaxial ultra-wideband Vivaldi antenna, characterized in that: The invention comprises a coaxial feeding structure (1), a fan-shaped feed source (2) and a metal cavity (3); the coaxial feeding structure (1) comprises a coaxial inner core (6) and a coaxial outer conductor (7); the coaxial inner core (6) is suspended inside the coaxial outer conductor; one end of the coaxial inner core (6) is connected to the fan-shaped feed source (2) through a coaxial matching section, and the other end is a free end; the fan-shaped feed source (2) is suspended in the metal cavity (3); a matching circular hole (8) is provided on the metal cavity (3) on one side of the fan-shaped feed source (2); the metal cavity (3) is provided with an exponential gradient curve opening (4); the matching circular hole (8) and the exponential gradient curve opening (4) are connected through a section of an inclined straight line gap; comb-shaped gaps (5) are provided on both sides of the metal cavity (3); and the metal cavity (3) is connected to the coaxial outer conductor (7).

2. The micro-coaxial ultra-wideband Vivaldi antenna according to claim 1, characterized in that: A plurality of SU-8 support structures (9) are arranged in an axial direction at intervals in a coaxial feeding structure (1), the SU-8 support structures (9) simultaneously connect the coaxial inner core and the coaxial outer conductor, and the SU-8 support structures (9) use a negative photoresist based on epoxy resin; a release hole (10) is arranged around the coaxial outer conductor of the coaxial feeding structure (1), the release holes (10) are symmetrically arranged about the axis of the coaxial feeding structure (1), and the cross section of the release hole (10) is rectangular.

3. The micro-coaxial ultra-wideband Vivaldi antenna according to claim 1, characterized in that: The exponential gradient curve opening (4) has a starting end width of 0.399 mm, an ending end width of 5.488 mm, and a distance between the starting end and the ending end of 7.949 mm.

4. The micro-coaxial ultra-wideband Vivaldi antenna according to claim 1, characterized in that: The other end of the coaxial inner core (6) is connected to the coaxial connector via a coaxial matching interface, and the coaxial matching interface matches the standard connector. At the coaxial matching interface, a cylindrical protrusion is provided on one side of the coaxial inner core (6), and a semicircular notch is provided on the coaxial outer conductor (7) corresponding to the side where the cylindrical protrusion is provided.

5. The micro-coaxial ultra-wideband Vivaldi antenna according to claim 1, characterized in that: The coaxial inner core (6), the coaxial outer conductor (7), the fan-shaped feed source (2), and the metal cavity (3) of the coaxial feeding structure (1) are all made of copper. The thickness of the coaxial outer conductor (7) and the metal cavity (3) is 0.9 mm, and the thickness of the coaxial inner core (6) and the fan-shaped feed source (2) is 0.3 mm.

6. The micro-coaxial ultra-wideband Vivaldi antenna according to claim 1, characterized in that: The width of the inclined straight line gap is equal to the width of the starting end of the exponential gradient curve opening (4).

7. The micro-coaxial ultra-wideband Vivaldi antenna according to claim 1, characterized in that: The metal cavity (3) is a rectangular parallelepiped cavity with a length of 11.65 mm and a width of 14.90 mm. The radius of the matching circular hole (8) is 0.84 mm.

8. The micro-coaxial ultra-wideband Vivaldi antenna according to claim 1, characterized in that: The width of the coaxial matching section is smaller than the width of the coaxial inner core (6), the coaxial matching section is located in the metal cavity (3), the coaxial matching section extends into the fan-shaped feed source (2) by a set length, and the coaxial matching section and the fan-shaped feed source (2) are integrally formed, and the fan-shaped angle of the fan-shaped feed source (2) is 90°.

9. The micro-coaxial ultra-wideband Vivaldi antenna according to claim 1, characterized in that: The comb-shaped gap (5) is symmetrical about the center line of the metal cavity (3), and the length of the comb-shaped gap (5) gradually shortens from the fan-shaped feed source to the opening end of the metal cavity (3).

10. A micro-coaxial ultra-wideband half-mode Vivaldi antenna, characterized in that: Based on the micro-coaxial ultra-wideband Vivaldi antenna according to any one of claims 1 to 9, the side of the metal cavity (3) where the matching circular hole (8) is not provided is removed, and the side where the metal cavity (3) is removed is set as a grid.

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