A sector pattern multi - frequency antenna for underground utility tunnel communication and its application

Abstract

The present invention relates to a fan-shaped pattern multi-frequency antenna for underground utility tunnel communication and its application, comprising: at least one antenna element, a feeding network and a grounding unit; the antenna element is arranged on one side of the grounding unit, and the antenna element includes a single-layer radiation structure and a feeding structure; the single-layer radiation structure includes a first electric dipole and a second electric dipole symmetrically arranged for forming resonance at a preset frequency; the feeding structure is arranged at intervals between the first electric dipole and the second electric dipole for coupling and feeding the first electric dipole and the second electric dipole, and simultaneously forming a high-frequency radiation effect. When the number of antenna elements is more than two, each antenna element is linearly arranged on the same side of the grounding unit; the feeding network is arranged on the other side of the grounding unit and is connected to each antenna element through a through hole reserved on the grounding unit to feed the antenna element. The present invention can be widely applied to the field of heterogeneous network fusion communication in underground utility tunnels.

Description

Technical Field

[0001] The present invention belongs to the field of electronic technology, and relates to the design of a multi-frequency antenna unit and an antenna for the heterogeneous network fusion communication requirements of urban underground utility tunnels, specifically to a sector pattern multi-frequency antenna for underground utility tunnel communication and its application, as well as the arrangement and excitation mechanism design of antenna units on the multi-frequency antenna. Background Art

[0002] In a new digital underground utility tunnel, a complex communication network needs to be built to support the realization of various services such as power IoT data collection, intelligent mobile inspection, and real-time communication between the ground and underground. It is necessary to select multiple wireless communication systems that meet the service requirements from multiple wireless technologies such as 4G / 5G, WiFi / WiFi6, NB-IoT, LoRa, ZigBee, Bluetooth, RFID, and WiFi for integrated networking. Therefore, the wireless network in the underground utility tunnel will be an integrated communication network with multiple networks deployed collaboratively and heterogeneous network fusion communication.

[0003] Currently, whip antennas are generally used for the transceiver antennas of wireless communication systems in utility tunnels. The whip antenna is a monopole antenna, which is a narrowband omnidirectional radiation antenna. Even with broadband design, it is difficult to meet the multi-band requirements of heterogeneous communication systems. On the other hand, omnidirectional antennas are not suitable for use in the utility tunnel scenario because the underground utility tunnel environment is a tunnel scenario with four sides closed and two ends open. The propagation characteristics of wireless signals in the utility tunnel are significantly different from those of the ground system. The multiple reflections of wireless signals on the four walls of the utility tunnel and the scattering caused by structures such as cable trays and cables deployed inside the utility tunnel will form a significant multi-path superposition effect. Therefore, the propagation characteristics of signals in the utility tunnel will show severe small-scale fading superimposed on large-scale fading, resulting in the phenomenon that there are periodically weak coverage areas along the extension direction of the utility tunnel.

[0004] Replacing the omnidirectional whip antenna with a directional antenna is one of the means to improve the coverage of wireless communication systems in utility tunnels. Existing technical methods mainly form a directional radiation beam through a log-periodic antenna, a planar directional antenna, or an antenna array, and deploy the beam direction along the utility tunnel. However, this method has two obvious deficiencies. One is that in the area close to the antenna, due to the narrow directional beam, only a very narrow space area pointed by the antenna beam can be covered, and there are large coverage blind areas around. The other is that in the area far from the antenna, when the directional beam is wide enough to cover the entire utility tunnel space, it will form reflections on the four walls of the utility tunnel, causing multi-path effects and resulting in poor coverage in the middle area. Summary of the Invention

[0005] Aiming at the integrated communication requirements of heterogeneous communication networks in urban underground utility tunnels and the coverage requirements in special scenarios of utility tunnels, the purpose of the present invention is to provide a sector pattern multi - frequency antenna for underground utility tunnel communication and its application, which meets the requirements of sharing communication antennas by multiple systems in utility tunnels, simplifies the deployment difficulty, and improves the resource utilization rate. At the same time, the sector radiation pattern of the multi - frequency antenna fits the physical structure of the square space of the utility tunnel, greatly reducing the coverage deterioration problem caused by the reflection of the four walls of the utility tunnel, and has important application value.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a sector pattern multi - frequency antenna for underground utility tunnel communication, including: at least one antenna unit, a feeding network, and a grounding unit; the antenna unit is arranged on one side of the grounding unit, and the structure of the antenna unit includes a single - layer radiation structure and a feeding structure; the single - layer radiation structure includes a first electric dipole and a second electric dipole symmetrically arranged, which are used to form resonance at a preset frequency; the feeding structure is arranged at intervals between the first electric dipole and the second electric dipole, which is used to couple - feed the first electric dipole and the second electric dipole, and at the same time form a high - frequency radiation effect. When the number of antenna units is more than two, each of the antenna units is linearly arranged on the same side of the grounding unit; the feeding network is arranged on the other side of the grounding unit and is connected to each of the feeding structures through through - holes reserved on the grounding unit to feed the antenna units.

[0008] Furthermore, the first electric dipole and the second electric dipole have the same structure, and both include a first vertical metal sheet, a second vertical metal sheet, a first horizontal metal sheet, and a second horizontal metal sheet; the first vertical metal sheet and the second vertical metal sheet are vertically and parallelly arranged, and the lower end of the first vertical metal sheet is connected to the grounding unit, while the lower end of the second vertical metal sheet is suspended; the first horizontal metal sheet is vertically arranged between the first vertical metal sheet and the second vertical metal sheet and is connected to the upper ends of the first vertical metal sheet and the second vertical metal sheet; the second horizontal metal sheet is vertically arranged at the lower end of the second vertical metal sheet and extends outward to form a "Ji" - shaped structure.

[0009] Furthermore, the second horizontal metal sheet adopts a triangular metal sheet.

[0010] Furthermore, the feeding structure is in an η shape and includes a third horizontal metal sheet, a third vertical metal sheet, and a fourth vertical metal sheet; the third horizontal metal sheet is fixedly arranged at a preset position of the grounding unit through a non-metallic support column; the third vertical metal sheet and the fourth vertical metal sheet are vertically arranged at both ends of the third horizontal metal sheet and extend downward, and are connected to both sides of the third horizontal metal sheet to form an η-shaped structure; the bottom of the third vertical metal sheet is connected to the feeding network through the grounding unit, and the distance between the connection of the third vertical metal sheet and the inner conductor probe and the grounding unit is a preset first height; the bottom of the fourth vertical metal sheet is suspended, and the distance between it and the grounding unit is a preset second height.

[0011] Furthermore, the third vertical metal sheet and the fourth vertical metal sheet are trapezoidal metal sheets, and the upper bottom edges of the third vertical metal sheet and the fourth vertical metal sheet are respectively connected to the third horizontal metal sheet.

[0012] Furthermore, the upper bottom edges of the third vertical metal sheet and the fourth vertical metal sheet are the same length as the short side of the third horizontal metal sheet.

[0013] Furthermore, the length of the lower bottom edge of the third vertical metal sheet is less than the length of the lower bottom edge of the fourth vertical metal sheet.

[0014] Furthermore, the feeding network includes a power divider, a power controller, and a phase shifter connected by feeding traces; the power divider is used to equally divide an input signal into at least one path of excitation signal and output it; the power controller is used to adjust the excitation signals on each path so that each antenna unit forms a fan-shaped radiation pattern; the phase shifter is used to compensate for the phase delay difference caused by the feeding network; the output end of the phase shifter passes through a circular hole provided on the grounding unit and is welded to the corresponding antenna units through an inner conductor probe.

[0015] Furthermore, the power controller uses a power amplifier or an attenuator.

[0016] In a second aspect, the present invention provides an application of a fan-shaped pattern multi-frequency antenna for underground pipe gallery communication. The antenna is deployed on the top of the pipe gallery, and the arrangement directions of the antenna units are the same as the pipe gallery direction, so that its radiation pattern is fan-shaped in the first plane and the second plane, and the fan-shaped angle, i.e., the half-power angle, is small in the first plane and large in the second plane, and the spatial electromagnetic wave irradiation range fits the physical structure of the pipe gallery. Among them, the first plane is determined by the antenna normal direction and the arrangement directions of the first electric dipole and the second electric dipole in the antenna unit; the second plane is determined by the antenna normal direction and the arrangement directions of the antenna units, and the antenna normal direction refers to the direction perpendicular to the plane where the grounding unit is located.

[0017] Due to the above technical solutions adopted by the present invention, it has the following advantages:

[0018] 1. The antenna of the present invention is composed of a plurality of antenna units arranged side by side, achieving three operating frequencies, and can well support the requirements of heterogeneous network fusion deployment in urban underground utility tunnels, such as the fusion deployment of Lora (768 MHz), Zigbee (2.4 GHz), and WiFi (2.4 GHz, 5.8 GHz), improving resource utilization rate, with a simple structure and low manufacturing cost, and is suitable for large-scale production.

[0019] 2. The antenna of the present invention generates a fan-shaped radiation pattern according to the characteristics of the utility tunnel structure, overcoming the problems of multipath effect formed by the reflection of the four walls of the utility tunnel by the omnidirectional antenna and the non-uniform coverage caused by the elliptical beam of the traditional directional antenna, effectively improving the coverage quality of the wireless network in urban underground utility tunnels, significantly reducing the usage amount of antenna devices required for continuous coverage, and reducing the network deployment cost.

[0020] Therefore, the present invention can be widely applied to the field of electronic technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. Throughout the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0022] Figure 1 is a schematic structural diagram of a fan-shaped pattern multi-frequency antenna for underground utility tunnel communication provided by an embodiment of the present invention;

[0023] Figures 2a to 2c is a schematic structural diagram of an antenna unit provided by an embodiment of the present invention, wherein, Figure 2a is a top view, Figure 2b is a front view; Figure 2c is a side view;

[0024] Figure 3 is a feeding network provided by an embodiment of the present invention;

[0025] Figure 4 is an antenna installation method provided by an embodiment of the present invention;

[0026] Figure 5 is a fan-shaped radiation pattern of the antenna provided by an embodiment of the present invention;

[0027] Figure 6 is a reflection loss curve of the antenna unit provided by an embodiment of the present invention;

[0028] Figure 7 is the 2D polar pattern in the 780 MHz band provided by the embodiments of the present invention;

[0029] Figure 8 is the 2D polar pattern in the 2.4 GHz band provided by the embodiments of the present invention;

[0030] Figure 9 is the 2D polar pattern in the 5.8 GHz band provided by the embodiments of the present invention;

[0031] Figure 10 is the 3D pattern in the 780 MHz band provided by the embodiments of the present invention;

[0032] Figure 11 is the 3D pattern in the 2.4 GHz band provided by the embodiments of the present invention;

[0033] Figure 12 is the 3D pattern in the 5.8 GHz band provided by the embodiments of the present invention. Detailed implementation manners

[0034] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present invention fall within the scope of protection of the present invention.

[0035] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0036] In some embodiments of the present invention, a multi - frequency antenna with a fan - shaped radiation pattern for underground utility tunnel communication includes: at least one antenna element, a feeding network, and a grounding unit; the antenna element is disposed on one side of the grounding unit, and the structure of the antenna element includes a single - layer radiation structure and a feeding structure; the single - layer radiation structure includes a first electric dipole and a second electric dipole symmetrically arranged, which are used to form resonance at a preset frequency; the feeding structure is spaced between the first electric dipole and the second electric dipole, which is used to couple - feed the first electric dipole and the second electric dipole and form a high - frequency radiation effect at the same time. When the number of antenna elements is more than two, each antenna element is linearly arranged on the same side of the grounding unit; the feeding network is disposed on the other side of the grounding unit and is connected to each feeding structure through a through - hole reserved on the grounding unit to feed the antenna element. The antenna provided by the present invention meets the requirements of sharing communication antennas in multiple systems in the utility tunnel, simplifies the deployment difficulty, and improves the resource utilization rate. At the same time, the fan - shaped radiation pattern of the multi - frequency antenna fits the physical structure of the square space in the utility tunnel, greatly reducing the coverage deterioration problem caused by the reflection of the four walls of the utility tunnel, and has important application value.

[0037] Correspondingly, in some other embodiments of the present invention, an application of a multi - frequency antenna with a fan - shaped radiation pattern for underground utility tunnel communication is also provided.

[0038] Embodiment 1

[0039] As Figure 1 、 Figure 3 shown, this embodiment provides a multi - frequency antenna with a fan - shaped radiation pattern for underground utility tunnel communication, which includes: at least one antenna element 1, a feeding network 2, and a grounding unit 3. Among them, the antenna element 1 is disposed on one side of the grounding unit 3, and the antenna element 1 includes a single - layer radiation structure 11 and a feeding structure 12. The single - layer radiation structure 11 includes a first electric dipole 111 and a second electric dipole 112 symmetrically arranged, which are used to form resonance at a preset frequency; the feeding structure 12 is spaced between the first electric dipole 111 and the second electric dipole 112, which is used to couple - feed the first electric dipole 111 and the second electric dipole 112 and form a high - frequency radiation effect at the same time. When the number of antenna elements 1 is more than two, each antenna element 1 is linearly arranged on the same side of the grounding unit 3; the feeding network 2 is disposed on the other side of the grounding unit 3 and is connected to each antenna element 1 through a through - hole reserved on the grounding unit 3 for feeding the antenna element 1.

[0040] Preferably, as Figure 2a 、 Figure 2bAs shown, the first dipole 111 and the second dipole 112 have the same structure, both including a first vertical metal sheet 113, a second vertical metal sheet 114, a first horizontal metal sheet 115, and a second horizontal metal sheet 116. Among them, the first vertical metal sheet 113 and the second vertical metal sheet 114 are arranged vertically and parallel to each other, and the lower end of the first vertical metal sheet 113 is connected to the grounding unit 3, while the lower end of the second vertical metal sheet 114 is suspended; the first horizontal metal sheet 115 is perpendicularly arranged between the first vertical metal sheet 113 and the second vertical metal sheet 114 and is connected to the upper ends of the first vertical metal sheet 113 and the second vertical metal sheet 114; the second horizontal metal sheet 116 is perpendicular to the second metal sheet 114 and is arranged at the lower end of the second vertical metal sheet 114 and extends outward, forming a "ji" - shaped structure.

[0041] Preferably, the second horizontal metal sheet 116 is a triangular metal sheet.

[0042] Preferably, the feeding structure 12 is in an η - shape, which includes a third horizontal metal sheet 121, a third vertical metal sheet 122, and a fourth vertical metal sheet 123. Among them, the third horizontal metal sheet 121 is fixedly arranged at a preset position of the grounding unit 3 through a non - metal support column (not shown in the figure), the third vertical metal sheet 122 and the fourth vertical metal sheet 123 are respectively perpendicularly arranged at both ends of the third horizontal metal sheet 121 and extend downward, and are connected to both sides of the third horizontal metal sheet 121 to form an η - shaped structure; the bottom of the third vertical metal sheet 122 is connected to the feeding network through the grounding unit 3, and the distance between the connection point of the third vertical metal sheet 122 and the feeding network 2 and the grounding unit 3 is a preset first height, which is convenient for the third vertical metal sheet 122 to be connected to the inner conductor probe of the feeding network 2 passing through the opening position on the grounding unit 3, and the preset first height can be 1 mm; the bottom of the fourth vertical metal sheet 123 is suspended, and the distance between it and the grounding unit 3 is a preset second height H4.

[0043] Preferably, the third vertical metal sheet 122 and the fourth vertical metal sheet 123 are trapezoidal metal sheets, and the upper base of the trapezoidal metal sheet is connected to the third horizontal metal sheet 121.

[0044] Preferably, in the η - shaped feeding structure, the upper bottom edges of the third vertical metal sheet 122 and the fourth vertical metal sheet 123 have the same length as the short side of the third horizontal metal sheet 121. More preferably, the length of the lower bottom edge of the third vertical metal sheet 122 is less than the length of the lower bottom edge of the fourth vertical metal sheet 123.

[0045] Preferably, the grounding unit 3 is a rectangular metal conductor plate, which is made of a good metal conductor, such as copper.

[0046] Preferably, the distance between each antenna unit 1 is λ m / 2, λm is the wavelength corresponding to the intermediate frequency.

[0047] Preferably, as Figure 3 shown, the feeding network 2 includes a power divider, a power controller, and a phase shifter connected by feeding traces. Among them, the power divider is used to equally divide the input signal into several paths of signals and output them; the power controller is used to adjust the voltage of the excitation signals on each path so that each antenna element forms a fan-shaped radiation pattern. For example, the voltage ratio of each path can be 1:1:2:1:1 from one side to the other side (the number of antenna elements can be adjusted according to actual needs, generally increased or decreased in pairs. When the number of antenna elements increases or decreases, the power ratio relationship and phase distribution between the antenna elements need to be re-optimized and designed to achieve a better fan-shaped radiation pattern effect); the phase shifter is used to compensate for the phase delay difference caused by the feeding network 2, so that the relative phase of the excitation signals reaching each antenna element 1 is controlled to be 180°, 0°, 0°, 0°, 180° from one side to the other side; the output end of the phase shifter passes through the circular hole provided on the grounding unit 3 and is welded to the feeding structure 12 corresponding to each antenna element 1 through an inner conductor probe.

[0048] Preferably, the power controller 22 uses a power amplifier or an attenuator.

[0049] Embodiment 2

[0050] As Figure 4 shown, this embodiment also provides an application of a fan-shaped pattern multi-frequency antenna for underground utility tunnel communication. During actual deployment, the antenna is deployed on the top of the utility tunnel, and the arrangement direction of each antenna element 1 in the antenna is the same as the direction of the utility tunnel, so that its radiation pattern is fan-shaped in the first plane and the second plane, and the half-power angle in the first plane is small, and the half-power angle in the second plane is large. The spatial electromagnetic wave irradiation range fits the physical structure of the utility tunnel. Among them, the first plane is determined by the antenna normal direction and the arrangement direction of the first electric dipole 111 and the second electric dipole 112 in the antenna element (i.e., Figure 1 the xoz plane in Figure 1 ); the second plane is formed by the antenna normal direction and the arrangement direction of each of the antenna elements (i.e.,

[0051] The multi-frequency antenna designed in this embodiment has a simple structure, and only uses a feeding structure and a single-layer radiation structure to form three low, medium and high operating frequency bands. Its structural parameters and operating frequency design comply with the design principles in Table 1. The antenna unit is directional radiation, the radiation direction is the direction of the antenna line, and the E plane and the H plane have good symmetry. Among them, in the single-layer radiation structure, the length of the first horizontal metal sheet 115 is recorded as L1, the width of the first horizontal metal sheet 115 is recorded as W1, the length of the second horizontal metal sheet 116 is recorded as L3, the height of the first vertical metal sheet 113 is recorded as H2, and the height of the second vertical metal sheet 114 from the ground unit 3 is recorded as H1; in the feeding structure 12, the height of the third vertical metal sheet 122 is recorded as H3; the height of the fourth vertical metal sheet 123 from the ground unit 3 is recorded as H4; the interval between the third vertical metal sheet 122 and the fourth vertical metal sheet 123 and the first vertical metal sheet 113 is recorded as g, the length of the third horizontal metal sheet 121 is recorded as L2, and the width of the third horizontal metal sheet 121 is recorded as W2; the bottom edge width of the third vertical metal sheet 122 is recorded as W3, and the bottom edge width of the fourth vertical metal sheet 124 is recorded as W4; then the parameters and λ m The relationship between them is shown in Table 1 below.

[0052] Table 1 Antenna unit size parameter design

[0053]

[0054]

[0055] Example 3

[0056] This embodiment uses the radio frequency full-wave simulation software Ansoft HFSS to simulate the antenna designed in Embodiment 1.

[0057] like Figure 5 As shown, the antenna designed in this embodiment has a fan-shaped radiation pattern characteristic, and its radiation pattern is fan-shaped in two directions perpendicular to the antenna. The fan-shaped angle is small on the cross section perpendicular to the corridor, and the beam half-power angle in this embodiment is approximately 60°. The fan-shaped angle is large on the cross section along the corridor, and the beam half-power angle in this embodiment is approximately 180°. Therefore, the electromagnetic wave radiation space radiated by the antenna designed in this embodiment fits the physical structure of the corridor, avoiding the energy waste caused by the excess electromagnetic wave energy irradiating the walls and top of both sides of the corridor, and also greatly reducing the multipath effect caused by the reflection of electromagnetic waves on the walls and top of both sides, thereby improving the uniformity of the wireless communication system coverage in the corridor. Therefore, the antenna designed in the present invention is very suitable for the deployment of wireless communication systems in corridor scenarios.

[0058] The structure of embodiment 1 of the present invention is as follows Figure 1 , Figure 2 and Figure 3 Its parameters are shown in Table 2.

[0059] Table 2 Structural Dimension Values of Example 1

[0060]

[0061] This embodiment is designed and implemented for three frequency bands: the 780 MHz Lora frequency band, the 2.4 GHz and 5.8 GHz WiFi frequency bands in China.

[0062] Figure 6 The reflection loss curve of the embodiment of the present invention is shown. Based on -10 dB, the three operating frequency bands of this antenna are 610.4 MHz - 920.8 MHz, 2.28 GHz - 2.49 GHz, and 5.80 G - 6.12 GHz respectively. The radiation patterns of this embodiment in the plane along the direction of the pipe gallery (Phi = 90°) and the plane perpendicular to the direction of the pipe gallery (Phi = 0°) in these three frequency bands are as Figures 7 to 9 shown, and the three-dimensional radiation pattern is as Figures 10 to 12 shown.

[0063] In summary, compared with the traditional whip antenna or the improved directional antenna, on the one hand, the antenna proposed by the present invention has the characteristic of multi-frequency operation, can realize the heterogeneous integration deployment of multiple communication networks, reduce the engineering implementation difficulty, and save costs; on the other hand, the radiation pattern of the antenna of the present invention has a fan-shaped characteristic, and the electromagnetic wave energy is confined in the long strip space along the direction of the pipe gallery, that is, it avoids the signal reflection caused by the pipe gallery wall, improves the energy utilization efficiency, and improves the coverage quality of the communication system in the pipe gallery.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fan-shaped pattern multi-frequency antenna for underground pipe gallery communication, characterized in that, Comprising: At least one antenna unit, a feeding network, and a grounding unit; The antenna unit is disposed on one side of the grounding unit. The antenna unit includes a single-layer radiation structure and a feeding structure. The single-layer radiation structure includes a first electric dipole and a second electric dipole symmetrically arranged for forming resonance at a preset frequency. The feeding structure is spaced between the first electric dipole and the second electric dipole for coupling and feeding the first electric dipole and the second electric dipole, and simultaneously forming a high-frequency radiation effect. When the number of the antenna units is more than two, each of the antenna units is linearly arranged on the same side of the grounding unit; The feeding network is disposed on the other side of the grounding unit and is connected to each of the feeding structures through through holes reserved on the grounding unit to feed the antenna unit; The first electric dipole and the second electric dipole have the same structure, and each includes a first vertical metal sheet, a second vertical metal sheet, a first horizontal metal sheet, and a second horizontal metal sheet. The first vertical metal sheet and the second vertical metal sheet are vertically and parallelly arranged, and the lower end of the first vertical metal sheet is connected to the grounding unit, and the lower end of the second vertical metal sheet is suspended. The first horizontal metal sheet is vertically disposed between the first vertical metal sheet and the second vertical metal sheet and is connected to the upper ends of the first vertical metal sheet and the second vertical metal sheet. The second horizontal metal sheet is vertically disposed at the lower end of the second vertical metal sheet and extends outward to form a "Ji" shaped structure; The second horizontal metal sheet is a triangular metal sheet; The feeding structure is in an η shape and includes a third horizontal metal sheet, a third vertical metal sheet, and a fourth vertical metal sheet. The third horizontal metal sheet is fixedly disposed at a preset position of the grounding unit through a non-metallic support column. The third vertical metal sheet and the fourth vertical metal sheet are vertically disposed at both ends of the third horizontal metal sheet and extend downward, and are connected to both sides of the third horizontal metal sheet to form an η shaped structure. The bottom of the third vertical metal sheet is connected to the feeding network through the grounding unit, and the distance between the connection of the third vertical metal sheet and the inner conductor probe and the grounding unit is a preset first height. The bottom of the fourth vertical metal sheet is suspended, and the distance between it and the grounding unit is a preset second height; The third vertical metal sheet and the fourth vertical metal sheet are trapezoidal metal sheets, and the upper bottom edges of the third vertical metal sheet and the fourth vertical metal sheet are respectively connected to the third horizontal metal sheet. The length of the lower bottom edge of the third vertical metal sheet is less than the length of the lower bottom edge of the fourth vertical metal sheet; The feeding network includes a power divider, a power controller, and a phase shifter connected by feeding traces. The power divider is used for equally dividing an input signal into at least one excitation signal and outputting it. The power controller is used for adjusting the excitation signals on each path so that each antenna unit forms a fan-shaped radiation pattern. The phase shifter is used for compensating the phase delay difference caused by the feeding network. The output end of the phase shifter passes through a circular hole provided on the grounding unit and is welded to the corresponding antenna units through inner conductor probes.

2. The multi - frequency antenna with a fan - shaped radiation pattern for underground utility tunnel communication according to claim 1, wherein The upper bottom edges of the third vertical metal sheet and the fourth vertical metal sheet have the same length as the short side of the third horizontal metal sheet.

3. The multi - frequency antenna with a fan - shaped radiation pattern for underground utility tunnel communication according to claim 1, wherein, The power controller uses a power amplifier or an attenuator.

4. Application of a sector pattern multi-frequency antenna for underground utility tunnel communication as described in any one of claims 1 to 3, characterized in that, The antenna is deployed on the top of the pipe gallery, and the arrangement directions of the antenna units are the same as the pipe gallery direction, so that its radiation pattern is fan-shaped in the first plane and the second plane, and the half-power angle in the first plane is small, and the half-power angle in the second plane is large. The spatial electromagnetic wave irradiation range fits the physical structure of the pipe gallery. Among them, the first plane is determined by the antenna normal direction and the arrangement directions of the first electric dipole and the second electric dipole in the antenna unit; the second plane is determined by the antenna normal direction and the arrangement directions of the antenna units. The antenna normal direction refers to the direction perpendicular to the plane where the grounding unit is located.

Images