Low-profile vertical polarization waveguide antenna structure

Abstract

A low-profile vertical polarization waveguide antenna structure provided by the present invention comprises a waveguide antenna, the waveguide antenna comprises a waveguide resonant cavity, a radiation slot, a wave beam constraint cavity and a waveguide feed line, the waveguide resonant cavity is an H-surface waveguide cavity, one end of the waveguide resonant cavity is closed and short-circuited, the other end of the waveguide resonant cavity leads to the waveguide feed line, and the radiation slot is arranged at a position close to the closed end. The radiation slot is arranged above the waveguide resonant cavity, one side of the radiation slot is parallel to the transmission direction of the waveguide resonant cavity, and the central point of the radiation slot is separated from the closed end of the waveguide resonant cavity by a certain distance and has a certain offset with the central plane of the transmission direction of the waveguide resonant cavity. And the wave beam constraint cavity is arranged above the radiation slot, is in an inverted horn shape, is connected with the radiation slot through an inclined plane or a step and penetrates through the top plane of the waveguide antenna.

Description

Technical Field

[0001] This invention relates to antenna structures adapted to low-altitude environments, and more particularly to a low-profile vertically polarized waveguide antenna structure. Background Technology

[0002] Existing antenna structures for low-altitude environments typically employ microstrip antennas, which have low radiation efficiency. Even when waveguide antennas are used, accurate vertical polarization is often impossible due to their layout, thus failing to meet the requirements of certain scenarios, such as the need for low-altitude aircraft to reduce signal attenuation caused by ground reflections and adapt to omnidirectional communication requirements in low-altitude environments. Furthermore, these antennas usually have a relatively high profile, making them unsuitable for small-size deployments. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a low-profile vertically polarized waveguide antenna structure, comprising a waveguide antenna including a waveguide resonant cavity, a radiating slot, a beam-constraining cavity, and a waveguide feed line. The waveguide resonant cavity is an H-plane waveguide cavity, with one end closed and short-circuited, and the other end connected to the waveguide feed line. Near the closed end, the radiating slot is positioned above the waveguide resonant cavity, with one side parallel to the transmission direction of the waveguide resonant cavity. The center point of the radiating slot is a certain distance from the closed end of the waveguide resonant cavity and offset from the center plane of the transmission direction of the waveguide resonant cavity. The beam-constraining cavity is positioned above the radiating slot and is shaped like an inverted horn, connected to the radiating slot by a slope or a step and penetrating the top plane of the waveguide antenna.

[0004] According to one aspect of the invention, a choke groove is provided around the beam-constraining cavity, the width and depth of the choke groove being 1 / 4 of the operating wavelength.

[0005] According to one aspect of the invention, the plane surrounding the beam-constraining cavity is higher than the top surface of the waveguide antenna structure by a certain height, the height being 1 / 4 of the operating wavelength.

[0006] According to one aspect of the invention, a choke slot is provided on a plane surrounding the beam-constraining cavity that is higher than the top surface of the waveguide antenna structure, the width and depth of the choke slot being 1 / 4 of the operating wavelength.

[0007] According to one aspect of the invention, the unclosed end of the waveguide resonant cavity is connected to the H-plane waveguide feed line via an H-plane matching body to form a signal transmission channel.

[0008] According to one aspect of the invention, the unclosed end of the waveguide resonant cavity is connected to the E-plane waveguide feed line via an EH matching body to form a signal transmission channel.

[0009] According to one aspect of the present invention, the waveguide antenna structure is fabricated in two separate upper and lower layers, and then assembled into an integral waveguide antenna structure.

[0010] According to one aspect of the present invention, the waveguide antenna structure is made of metal or non-metallic materials such as plastic and then subjected to surface metallization treatment.

[0011] According to one aspect of the invention, the distance between the center point of the radiating slot and the closed end of the waveguide resonant cavity is 1 / 4 of the waveguide wavelength, the radiating slot has a rectangular cross-section, and the long side of the rectangle is parallel to the transmission direction of the waveguide resonant cavity.

[0012] The present invention also provides an antenna array comprising a plurality of the aforementioned low-profile vertically polarized waveguide antenna structures, wherein the plurality of waveguide antenna structures are arranged in rows and columns to form the antenna array, wherein the spacing between adjacent waveguide antenna structures is 1.5 times the wavelength. Attached Figure Description

[0013] Figure 1 A perspective view of a vertically polarized waveguide antenna according to the present invention is shown; Figure 2 A top view of a vertically polarized waveguide antenna according to the present invention is shown; Figure 3 The vertically polarized waveguide antenna according to the present invention is shown along... Figure 2 The sectional view obtained by the cutting line AA in the middle; Figure 4 A perspective view of a vertically polarized waveguide antenna connected to an H-plane waveguide according to the present invention is shown. Figure 5 A perspective view of a vertically polarized waveguide antenna connected to an E-plane waveguide according to the present invention is shown. Figure 6 A perspective view of an integral antenna structure with a choke slot for a vertically polarized waveguide antenna according to the present invention is shown. Figure 7 An overview diagram of one embodiment of the multi-channel vertically polarized waveguide antenna according to the present invention is shown. Detailed Implementation

[0014] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that these descriptions of embodiments are intended only to aid in understanding the present invention and do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0015] The embodiments of the present invention will now be described with reference to the accompanying drawings. It should be noted that the positional relationships between the various components in the present invention are described with reference to the horizontal and vertical directions shown in the accompanying drawings.

[0016] Reference Figures 1-5 As can be seen, the low-profile vertically polarized waveguide antenna structure 1 according to the present invention includes a waveguide antenna 2. The waveguide antenna 2 generally includes a waveguide resonant cavity 21, a radiation slot 22, a beam confinement cavity 23, and waveguide feed lines 25 and 26. The waveguide resonant cavity 21 is an H-plane waveguide cavity, with one end closed and short-circuited, and the other end extending horizontally to the waveguide feed lines 25 and 26 as shown in the figure. The closed and short-circuited end produces ideal total internal reflection of the incident electromagnetic wave, causing the incident wave and the reflected wave to superimpose, thereby forming a stable standing wave field within the resonant cavity 21. Near the aforementioned closed end, the radiation slot 22 is disposed above and connected to the waveguide resonant cavity 21, as shown in the figure. Figure 2 As shown more clearly, the radiating slot 22 has a rectangular cross-section, with its long side parallel to the transmission direction of the waveguide resonator 21. The center point of the radiating slot 22 is spaced a certain distance from the closed end of the waveguide resonator 21, which is 1 / 4 of the waveguide wavelength. Furthermore, the center point of the radiating slot 22 is offset from the center plane of the transmission direction of the waveguide resonator 21. This 1 / 4 waveguide wavelength distance design allows for precise matching with the radiation impedance of the radiating slot 22, thereby reducing energy reflection and ensuring stable operation of the antenna or radiating structure. Additionally, since the electric field is strongest at the center plane and gradually weakens towards both sides in the dominant mode of the H-plane waveguide, the electric field strength coupled to the radiating slot 22 can be precisely controlled by changing the offset of the radiating slot 22, thus adjusting the equivalent impedance and coupling coefficient of the radiating slot 22. The beam-constraining cavity 23 is positioned above and connected to the radiating slot 22. Figure 1 As can be seen, the beam confinement cavity 23 is shaped like an inverted horn, or it can be connected to the radiation slot 22 via a slope or a step and penetrate the top plane of the waveguide antenna. Using a horn-shaped or stepped beam confinement cavity 23 can shape the radiation field, concentrate energy more in a specific direction, thereby compressing the beamwidth and improving the directional gain of the antenna.

[0017] from Figure 1 As can be seen, the waveguide antenna structure 1 itself is a complete cavity, and all waveguide transmission, radiation, and even power division functions are realized inside this cavity. This design eliminates the vertical transition structure used to connect different modules in traditional antennas, thereby reducing the overall height of the antenna. In addition, the waveguide resonant cavity 21 extends along the horizontal direction shown in the figure, which further reduces the overall height of the antenna, making the antenna structure a compact structure with a low profile.

[0018] like Figure 2 , Figure 3 and Figure 6 As shown, several choke slots 24 can be arranged around the beam-constraining cavity 23, thereby suppressing surface waves and edge parasitic radiation and improving impedance matching and standing wave characteristics. Additionally, in Figure 7 In the illustrated embodiment comprising multiple waveguide antenna structures 1 arranged in an array, the choke slot 24 positioned around the beam-constraining cavity 23 forms an electromagnetic barrier around each beam-constraining cavity 23, disrupting the propagation path of surface waves. This blocks parasitic current coupling between the individual waveguide antenna structures 1, effectively reducing mutual coupling effects between antenna elements. Preferably, the width and depth of the choke slot 24 are 1 / 4 of the operating wavelength. This allows for further adjustment of the beamwidth and pointing, and increases the isolation between multi-channel antenna elements.

[0019] In addition, from Figure 3 It can be seen that the plane surrounding the beam-constraining cavity 23 can be higher than the top surface of the waveguide antenna by a certain height, which is 1 / 4 of the operating wavelength. This height of 1 / 4 of the operating wavelength causes the surface wave propagating along the surface to have a 90° phase difference when it reaches the edge due to the difference in path length. After superimposing with the reflected wave, it forms an equivalent open circuit, thereby effectively blocking the propagation of the surface wave and suppressing parasitic radiation and energy leakage at the aperture edge. Figure 3 In one embodiment, the choke slot 24 is disposed on a plane surrounding the beam confinement cavity 23 that is higher than the top surface of the waveguide antenna.

[0020] Reference Figure 4 and Figure 5 These figures respectively show perspective views of a vertically polarized waveguide antenna according to the present invention, connecting an H-plane waveguide and an E-plane waveguide. Figure 4 As shown, the H-plane waveguide resonant cavity 21 is connected to the H-plane waveguide feed line 25 via an H-plane matching body 25a to form a signal transmission channel. The H-plane matching body 25a is preferably a sloping structure. The H-plane waveguide feed line 25 is perpendicular to the H-plane waveguide resonant cavity 21 extending horizontally as shown in the figure, and extends vertically to the sidewall of the waveguide antenna structure, thereby reducing the length of the antenna structure in both the horizontal and vertical directions, and further reducing the overall size of the antenna structure. Similarly, as... Figure 5 As shown, the H-plane waveguide resonant cavity 21 is connected to the E-plane waveguide feed line 26 through the EH matching body 26a to form a signal transmission channel. Specifically, the E-plane waveguide feed line 26 is perpendicular to the H-plane waveguide resonant cavity 21 extending in the horizontal direction shown in the figure through the EH matching body 26a and extends in the vertical direction shown in the figure to the sidewall of the waveguide antenna structure. This also reduces the length of the antenna structure in the horizontal and vertical directions shown in the figure, thereby further reducing the overall size of the antenna structure.

[0021] exist Figure 5In the antenna, the H-plane waveguide resonator 21 is connected to the E-plane waveguide feed line 26 through the EH matching body 26a. Due to the structural difference between the H-plane waveguide resonator 21 and the E-plane waveguide feed line 26, there is a height difference at the connection point (i.e., at the EH matching body 26a). This may slightly increase the overall height of the antenna structure, but in return, it results in a significant reduction in the overall size of the antenna structure.

[0022] Furthermore, in Figure 4 and Figure 5 In the illustrated embodiment, the waveguide antenna structure can be divided into upper and lower layers, which are processed separately and then assembled into a whole. Thus, it can be seen that... Figure 5 The height increase of the E-plane waveguide feed line 26 can be placed in the lower structure, so that the overall height of the waveguide antenna structure will not increase.

[0023] Figure 7 An embodiment of the multi-channel vertically polarized waveguide antenna according to the present invention is shown, comprising a plurality of waveguide antennas 2 arranged in an array. Although three waveguide antennas 2 are shown in the figure, it will be understood that the number of waveguide antennas 2 can be any. These waveguide antennas are configured in a row and column array and are spaced apart from each other, the spacing preferably being 1.5 times the wavelength. A choke slot 24 is used to block mutual coupling between these waveguide antennas 2.

[0024] The waveguide antenna of this invention has a design structure that conforms to the precision characteristics of conventional metal processing, die casting, injection molding and other processes, and is simple to manufacture and has controllable cost.

[0025] The waveguide antenna structure of the present invention can be made of metal or non-metallic materials such as plastic and then subjected to surface metallization treatment.

[0026] The waveguide antenna structure of this invention features high vertical polarization, making it particularly suitable for millimeter-wave frequencies. It is applicable to fields such as vehicle-mounted radar, aerospace radar, and communications, and is especially suitable for low-altitude aircraft, reducing signal attenuation caused by ground reflection and meeting the omnidirectional communication requirements of low-altitude environments. Furthermore, the waveguide antenna structure of this invention is compact, with the profile height of the complete structure controllable within 1-1.5 times the operating wavelength.

[0027] In this invention, the waveguide resonant cavity is arranged horizontally. The distance between the center point of the radiation slot and the closed end of the waveguide resonant cavity is approximately 1 / 4 of the waveguide wavelength. The long side of the radiation slot is parallel to the transmission direction of the waveguide resonant cavity, and the center point of the radiation slot is offset from the center plane of the transmission direction of the waveguide resonant cavity by a certain amount. The radiation slot cuts the current on the top surface of the waveguide resonant cavity, forming resonant radiation. Furthermore, because the radiation slot is arranged laterally, vertically polarized radiation is formed.

[0028] Choke slots are set around the beam-constraining cavity; the choke slots cut the surface current of the waveguide antenna body, which can improve the spatial coupling of the radiation space. By adjusting the distance between the choke slots and the radiation slots, the radiation directivity, i.e., the normal gain level and beamwidth, can be adjusted. Moreover, the choke slots cut off the surface current, reducing the surface wave coupling of adjacent antennas, which can further improve the isolation between adjacent radiating antennas.

[0029] The plane surrounding the beam-constraining cavity can be raised to a certain height above the top surface of the waveguide antenna, increasing the height of the beam-constraining cavity, typically by more than 1 / 2 wavelength. This effectively improves radiation gain and controls beamwidth. Simultaneously, maintaining the height of the top plane of the waveguide antenna outside the beam-constraining cavity and choke slot creates a height difference of approximately 1 / 4 wavelength. This height difference results in a path difference or phase difference of 1 / 2 wavelength between the reflected wave from the top surface of the remaining waveguide antenna and the radiated wave from the radiation slot. This further effectively suppresses spatial coupling between radiated and reflected waves, suppresses pattern jitter, and improves the gain flatness of the radiation pattern, especially when an antenna radome is present.

[0030] In the description of this invention, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention.

[0031] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments.

[0032] For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A low-profile vertically polarized waveguide antenna structure, comprising a waveguide antenna, the waveguide antenna comprising: The system comprises a waveguide resonant cavity, a radiating slot, a beam-constraining cavity, and a waveguide feed line. The waveguide resonant cavity is an H-plane waveguide cavity, with one end closed and short-circuited, and the other end connected to the waveguide feed line. Near the closed end, the radiating slot is positioned above the waveguide resonant cavity. One side of the radiating slot is parallel to the transmission direction of the waveguide resonant cavity, and the center point of the radiating slot is a certain distance from the closed end of the waveguide resonant cavity and offset from the center plane of the transmission direction of the waveguide resonant cavity. The beam-constraining cavity is positioned above the radiating slot and is shaped like an inverted horn, connected to the radiating slot by a slope or a step, and penetrates the top plane of the waveguide antenna.

2. The low-profile vertically polarized waveguide antenna structure as described in claim 1, wherein a choke slot is provided around the beam-constraining cavity, and the width and depth of the choke slot are 1 / 4 times the operating wavelength.

3. The low-profile vertically polarized waveguide antenna structure as described in claim 1, wherein the plane surrounding the beam-constraining cavity is higher than the top surface of the waveguide antenna structure by a certain height, the height being 1 / 4 times the operating wavelength.

4. The low-profile vertically polarized waveguide antenna structure as described in claim 3, wherein a choke slot is provided on a plane surrounding the beam-constraining cavity that is higher than the top surface of the waveguide antenna structure, and the width and depth of the choke slot are 1 / 4 times the operating wavelength.

5. The low-profile vertically polarized waveguide antenna structure as described in any one of claims 1-4, wherein the unclosed end of the waveguide resonant cavity is connected to the H-plane waveguide feed line via an H-plane matching body to form a signal transmission channel.

6. The low-profile vertically polarized waveguide antenna structure as described in any one of claims 1-4, wherein the unclosed end of the waveguide resonant cavity is connected to the E-plane waveguide feed line through an EH matching body to form a signal transmission channel.

7. The low-profile vertically polarized waveguide antenna structure as described in any one of claims 1-4, wherein the waveguide antenna structure is fabricated in two separate upper and lower layers and then assembled into an integral waveguide antenna structure.

8. The low-profile vertically polarized waveguide antenna structure as described in any one of claims 1-4, wherein the waveguide antenna structure is made of metal or non-metallic materials such as plastic and then surface-metallized.

9. The low-profile vertically polarized waveguide antenna structure as described in any one of claims 1-4, wherein the distance between the center point of the radiation slot and the closed end of the waveguide resonant cavity is 1 / 4 of the waveguide wavelength, the radiation slot has a rectangular cross-section, and the long side of the rectangle is parallel to the transmission direction of the waveguide resonant cavity.

10. An antenna array comprising a plurality of low-profile vertically polarized waveguide antenna structures as described in any of the preceding claims, wherein the plurality of waveguide antenna structures are arranged in rows and columns to form the antenna array, wherein the spacing between adjacent waveguide antenna structures in the plurality of waveguide antenna structures is 1.5 times the wavelength.

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