A low-ovality ultra-wideband planar omnidirectional antenna

Abstract

The application discloses a low-irregularity ultra-wideband planar omnidirectional antenna, which comprises a planar tightly-coupled omnidirectional antenna array, an eight-way broadband Wilkinson power divider and a curved truncated cone reflector. The planar tightly-coupled omnidirectional antenna array is composed of a coupling patch loaded tightly-coupled dipole, a microstrip tapered balun, an arc-shaped director and a two-way Wilkinson power divider. The eight-way broadband Wilkinson power divider is composed of four two-way Wilkinson power dividers in parallel, and is used for balanced feeding and impedance transformation of the omnidirectional antenna disc. The curved truncated cone reflector is loaded on the upper and lower sides of the omnidirectional antenna, so that the beam width of the omnidirectional antenna in the horizontal direction is improved, and the electromagnetic interference on the upper and lower sides is isolated, and finally the design of the broadband omnidirectional tightly-coupled antenna is completed. The application adopts the tightly-coupled structure, has the advantages of broadband, planarization, low irregularity and miniaturization and easiness in integration, and can be applied to the field of high-performance radars and electronic countermeasure systems.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of communication, and further relates to a low-irregularity ultra-wideband planar omnidirectional antenna in the field of electromagnetic field and microwave technology. BACKGROUND

[0002] As a key component for receiving and transmitting electromagnetic waves in a wireless communication system, an antenna is widely used in various civilian and military communication fields such as wireless communication, broadcasting, navigation, radar, measurement and control, remote sensing and electronic countermeasure. In order to strengthen the directivity of the antenna, a plurality of radiation units can be arranged in a specific manner to form an antenna system, which is called an array antenna. The traditional array design is based on designing an independent array unit that meets the bandwidth and radiation characteristics, and the mutual coupling effect between the array elements in the array environment is not considered. However, the excessive mutual coupling effect in the array often causes the port impedance and the radiation pattern of the array elements to change dramatically. In order to eliminate the influence of the coupling between the array elements and improve the performance of the array, the decoupling technology for the array often becomes a difficulty in the design of the array. For a phased array, the appearance of the grating lobe may be accompanied by a decrease in antenna gain and a discontinuity in port impedance. For these reasons, it is usually required that the distance between the array elements is less than one-half wavelength. Therefore, in the design of the traditional array, the design of the decoupling structure and the limitation of the distance between the array elements make it difficult for the array to balance the technical indicators such as the working bandwidth and the beam scanning. A wideband array with good radiation characteristics is usually composed of a spiral, a tapered slot or a logarithmic periodic unit, but these units have a large size, a high profile and are not easy to design in a planar manner. SUMMARY

[0003] The application aims to overcome the shortcomings of the prior art and provides a low-irregularity ultra-wideband planar omnidirectional antenna to solve the problems of insufficient wideband and poor omnidirectionality of the existing omnidirectional array.

[0004] The specific idea for realizing the application is as follows: first, a planar tightly coupled omnidirectional antenna array is proposed to realize omnidirectional radiation characteristics in a wide frequency band. Then, an eight-way broadband Wilkinson power divider is used to feed the planar tightly coupled omnidirectional antenna array, and the eight-way broadband Wilkinson power divider is composed of four two-way Wilkinson power dividers in parallel to realize balanced feeding and impedance transformation in a wide frequency band. Finally, a curved surface circular truncated cone reflector is loaded on the upper and lower sides of the omnidirectional antenna to improve the beam width in the horizontal direction of the omnidirectional antenna and isolate electromagnetic interference on the upper and lower sides, thereby completing the design of the wideband omnidirectional tightly coupled antenna.

[0005] To achieve the above object, the technical scheme adopted by the application is as follows:

[0006] A low-ovality ultra-wideband planar omnidirectional antenna, comprising a planar tightly coupled omnidirectional antenna array and an eight-way broadband Wilkinson power divider; the planar tightly coupled omnidirectional antenna array comprises a coupling patch loaded tightly coupled dipole, a microstrip tapered balun, an arc-shaped director and a two-way Wilkinson power divider A;

[0007] The coupling patch loaded tightly coupled dipole is in a plurality of annular arrays, each coupling patch loaded tightly coupled dipole is composed of a coupling patch and a dipole;

[0008] The microstrip tapered balun is in a plurality of annular arrays on the inner side of the coupling patch loaded tightly coupled dipole, the feed line and the ground plate of each microstrip tapered balun are connected to the two dipoles of one coupling patch loaded tightly coupled dipole respectively;

[0009] The arc-shaped director is in a plurality of annular arrays on the outer side of the coupling patch loaded tightly coupled dipole;

[0010] The two-way Wilkinson power divider A is in a plurality of annular arrays, each two-way Wilkinson power divider A is connected to two microstrip tapered baluns for equal-radiation and in-phase feeding;

[0011] The eight-way broadband Wilkinson power divider is composed of four two-way Wilkinson power dividers B in parallel, the output port of the eight-way broadband Wilkinson power divider is connected to the input port of the two-way Wilkinson power divider A.

[0012] In one embodiment, the microstrip tapered balun adopts an exponential tapering curve, and the curve equation is y=0.04e 0.66x , wherein x is the horizontal width of the microstrip tapered balun, and y is the extension length of the microstrip tapered balun in millimeters.

[0013] In one embodiment, the coupling patch is printed on the upper side of the medium substrate, the dipole is printed on the lower side of the medium substrate, the arc-shaped director is printed on the lower side of the medium substrate, the feed line of the two-way Wilkinson power divider B is printed on the lower side of the medium substrate, the ground plate is printed on the upper side of the medium substrate, and the output port of the eight-way broadband Wilkinson power divider is connected to the input port of the two-way Wilkinson power divider A through a metallized via.

[0014] In one embodiment, the number of the coupling patch loaded tightly coupled dipoles is the same as that of the microstrip tapered baluns, and is 2 times the number of the two-way Wilkinson power divider A, the arc-shaped director has two layers, the number of the layer close to the coupling patch loaded tightly coupled dipoles is 2 times the number of the microstrip tapered baluns, and the number of the layer away from the coupling patch loaded tightly coupled dipoles is the same as that of the microstrip tapered baluns.

[0015] In one embodiment, the number of the coupling patch loaded tight coupled dipoles and the microstrip tapered baron is wherein S d is the arc length of the coupling patch loaded tight coupled dipole, R3 is the length of the coupling patch loaded tight coupled dipole from the center, and [] is the integral symbol.

[0016] In one embodiment, a first isolation resistor is loaded in the middle of each of the one-to-two Wilkinson power dividers A to ensure the isolation degree between the two output ports; and a second isolation resistor is loaded in the middle of each of the one-to-two Wilkinson power dividers B to ensure the isolation degree between the two output ports.

[0017] In one embodiment, the resistance values of the first isolation resistor and the second isolation resistor are preferably equal to 100Ω.

[0018] In one embodiment, the one-to-two Wilkinson power dividers B are composed of five sections of microstrip lines with gradually changed width and the second isolation resistor.

[0019] In one embodiment, the four one-to-two Wilkinson power dividers B are distributed in a central symmetry, and the input port is at the center of symmetry. Along the input port, the width of the five sections of microstrip lines of each one-to-two Wilkinson power divider B gradually changes according to the following rules:

[0020] From the first section of the microstrip line to the third section of the microstrip line, the width gradually increases, and the corresponding characteristic impedance of the microstrip line gradually decreases;

[0021] The fourth section of the microstrip line has a width smaller than that of the third section, and the corresponding characteristic impedance of the microstrip line increases. The fourth section of the microstrip line is divided into two parts, which are connected to the third section of the microstrip line, respectively, to realize impedance matching of the two fourth sections of the microstrip line in parallel connection in the one-to-two structure with the third section of the microstrip line. The second isolation resistor is connected between the two fourth sections of the microstrip line.

[0022] The fifth section of the microstrip line has a width larger than that of the third section, and the corresponding characteristic impedance of the microstrip line decreases, to realize impedance matching with the one-to-two Wilkinson power divider A.

[0023] In one embodiment, the low non-circularity ultra-wideband planar omnidirectional antenna further comprises:

[0024] a curved truncated cone reflector;

[0025] The curved truncated cone reflector is composed of a truncated cone with a curved side surface, is loaded on the upper side of the planar tight coupled omnidirectional antenna array and the lower side of the one-to-eight broadband Wilkinson power divider, respectively, and the area of the side surface close to the planar tight coupled omnidirectional antenna array is smaller than the area of the side surface away from the planar tight coupled omnidirectional antenna array.

[0026] Compared with the prior art, the present application has the following advantages:

[0027] First, in order to solve the problem of narrow operating bandwidth of the loop omnidirectional antenna, the loop strong electromagnetic coupling array technology and the wide-angle impedance matching technology are adopted in the loop array antenna design, so that the ultra-wideband operating characteristics of the loop array antenna are realized.

[0028] Second, in order to solve the problem of limited space for the feed network design, a new type of ultra-wideband feed network with compact arrangement of the balun and the power divider is proposed, and the influence of the feed structure on the directivity pattern non-circularity performance of the array is reduced by staggered design of the feed network.

[0029] Third, in order to meet the demand of the project for the directivity pattern of the omnidirectional antenna, the periodic metal director and the curved reflector are introduced outside the antenna, so as to optimize the beam directivity pattern coverage range and the non-circularity performance, and effectively improve the beam stability of the antenna in the ultra-wideband. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a schematic diagram of the overall structure of the present application.

[0031] Figure 2 is a schematic diagram of the planar tight coupling omnidirectional antenna array structure of the present application.

[0032] Figure 3 is a schematic diagram of the one-to-eight broadband Wilkinson power divider structure of the present application.

[0033] Figure 4 is a schematic diagram of the curved truncated cone reflector of the present application.

[0034] Figure 5 is the active standing wave ratio curve of the antenna in the simulation experiment of the present application.

[0035] Figure 6 is the azimuth plane radiation pattern of the antenna in the simulation experiment of the present application.

[0036] Figure 7 is the elevation plane radiation pattern of the antenna in the simulation experiment of the present application. DETAILED DESCRIPTION

[0037] In order to make the purpose and advantages of the present application clearer and more obvious, the present application will be described in detail below with reference to the drawings:

[0038] Reference Figure 1 and Figure 2 The low non-circularity ultra-wideband planar omnidirectional antenna of the present application mainly includes a planar tight coupling omnidirectional antenna array 1 and a one-to-eight broadband Wilkinson power divider 2. The planar tight coupling omnidirectional antenna array 1 mainly includes a coupling patch loaded tight coupling dipole 11, a microstrip tapered balun 12, an arc-shaped director 13 and a one-to-two Wilkinson power divider A 14, wherein:

[0039] The coupling patch loaded tight coupled dipoles 11 are in a circular array, each of which is composed of a coupling patch and a dipole. The coupling patch loaded tight coupled dipoles 11 are radiation units of the low non-circularity ultra-wideband planar omnidirectional antenna, which realize the omnidirectional radiation characteristics by arranging in a circular ring structure.

[0040] The microstrip tapered baluns 12 are in a circular array on the inner side of the coupling patch loaded tight coupled dipoles 11, and the feed line and the ground plate of each microstrip tapered balun 12 are connected to the two dipoles of one coupling patch loaded tight coupled dipole 11. Here, the inner side refers to the inner side of the ring formed by the coupling patch loaded tight coupled dipoles 11. The microstrip tapered baluns 12 feed the coupling patch loaded tight coupled dipoles 11 and realize the impedance transformation function through their tapered structure.

[0041] The arc-shaped directors 13 are in a circular array on the outer side of the coupling patch loaded tight coupled dipoles 11. Similarly, the outer side here refers to the outer side of the ring formed by the coupling patch loaded tight coupled dipoles 11. The main function of the arc-shaped directors 13 is to improve the impedance matching of the coupling patch loaded tight coupled dipoles 11, and at the same time, optimize the radiation pattern of the ultra-wideband planar omnidirectional antenna and improve the non-circularity.

[0042] The one-to-two Wilkinson power dividers A 14 are also in a circular array, each of which is connected to two microstrip tapered baluns 12 for equal amplitude and in-phase feeding. Through the one-to-two Wilkinson power dividers A 14, equal amplitude and in-phase excitation from one port to two ports in a wide frequency band range can be realized.

[0043] The one-to-eight broadband Wilkinson power divider 2 is composed of four one-to-two Wilkinson power dividers B21 in parallel, and the output port of the one-to-eight broadband Wilkinson power divider 2 is connected to the input port of the one-to-two Wilkinson power divider A 14 to realize energy transmission.

[0044] The present application adopts a tight coupling structure, has the characteristics of wide frequency band and low non-circularity, and can be applied to the field of high-performance radar and electronic countermeasure systems.

[0045] In order to avoid the coupling between the units, the distance between the units is usually half of the working wavelength. In the embodiment of the application, the dipole units are arranged closely together to form the capacitive coupling between the units, so as to expand the working frequency band. In order to further expand the bandwidth, the coupling sheet is loaded between the adjacent dipole units to form a larger inter-unit capacitance, so as to offset the inductance of the metal floor and realize the impedance matching characteristic of the ultra-wideband. For example, in the implementation process, the coupling sheet and the dipole are printed on the two sides of the dielectric substrate, for example, the coupling sheet can be printed on the upper side of the dielectric substrate, and the dipole is printed on the lower side of the dielectric substrate.

[0046] In some embodiments of the application, the microstrip tapered balun 12 realizes the impedance transformation function through its tapered structure. Specifically, the microstrip tapered balun 12 can adopt an exponential tapered curve, and a typical curve equation is y = 0.04e 0.66x , wherein x is the horizontal width of the microstrip tapered balun, and y is the extension length of the microstrip tapered balun, in millimeters.

[0047] In some embodiments of the application, the number of the coupling sheet loaded tight coupling dipoles 11 and the microstrip tapered baluns 12 is 2 times the number of the Wilkinson power divider A 14. For example, the number of the coupling sheet loaded tight coupling dipoles 11 and the microstrip tapered baluns 12 is , wherein S d is the arc length of the coupling sheet loaded tight coupling dipole 11, R3 is the length of the coupling sheet loaded tight coupling dipole 11 from the center of the circle, the width of the coupling sheet loaded tight coupling dipole 11 is W3, and [] is the integral symbol. The larger n is, the lower the non-circularity of the planar omnidirectional antenna is. In this example, n = 16.

[0048] In some embodiments of the application, the feed line of the microstrip tapered balun 12 is connected to the first dipole of the coupling sheet loaded tight coupling dipole 11 through the metallized via, and the ground plate of the microstrip tapered balun 12 is directly connected to the second dipole of the coupling sheet loaded tight coupling dipole 11. The width of the feed line is W4, the length is L b , and the length from the center of the circle is R5. Here, the first dipole is the left arm in Figure 2 , and the second dipole is the right arm in Figure 2 .

[0049] In some embodiments of the application, the arc-shaped director 13 has two layers, which are printed on the lower side of the dielectric substrate and close to one layer of the coupling sheet loaded tight coupling dipole 11. The number of the layer is 2 times the number of the microstrip tapered balun 12, and the number of the layer far away from the coupling sheet loaded tight coupling dipole 11 is the same as the number of the microstrip tapered balun 12, so as to form the corresponding structure.

[0050] In the embodiment, the inner arc-shaped director 13 mainly improves the impedance matching of the coupling-plate-loaded tight-coupling dipole 11 and improves the gain of the antenna. The width of the inner arc-shaped director 13 is W2, and the length of the inner arc-shaped director 13 from the center of the disc is R2. The outer arc-shaped director 13 mainly optimizes the non-circularity of the ultra-wideband planar omnidirectional antenna. The width of the outer arc-shaped director 13 is W1, the length of the outer arc-shaped director 13 from the center of the disc is R1, and the arc length of the director is S. r .

[0051] In some embodiments of the application, a first isolation resistor is loaded in the middle of each one-to-two Wilkinson power divider A14 to ensure better isolation between the two output ports. The length of the input port from the center of the disc is R4.

[0052] In some embodiments of the application, a second isolation resistor is loaded in the middle of each one-to-two Wilkinson power divider B21 to ensure better isolation between the two output ports. For example, the resistance values of the first isolation resistor and the second isolation resistor are equal. Considering the port isolation and insertion loss of the one-to-two Wilkinson power divider, the resistance values of the first isolation resistor and the second isolation resistor are both 100Ω in the embodiments of the application. Isolation resistors with other resistance values may cause the performance of the one-to-two Wilkinson power divider to decrease.

[0053] In some embodiments of the application, the one-to-two Wilkinson power divider B21 is composed of five segments of width-gradually-changing microstrip lines and a second isolation resistor. The feed line is printed on the lower side of the dielectric substrate, and the ground plane is printed on the upper side of the dielectric substrate. The one-to-eight broadband Wilkinson power divider 2 is connected to the input port of the one-to-two Wilkinson power divider A14 of the planar tight-coupling omnidirectional antenna array 1 through a metallized via. The height of the metallized via is H3=3mm.

[0054] As shown in Figure 3 the four one-to-two Wilkinson power dividers B21 in the embodiments of the application are centrally symmetrically distributed. The input port of each one-to-two Wilkinson power divider B21 is at the center of symmetry. Along the input port, the five segments of microstrip lines of each one-to-two Wilkinson power divider B21 are: a first segment of microstrip lines, a second segment of microstrip lines, a third segment of microstrip lines, a fourth segment of microstrip lines, and a fifth segment of microstrip lines. The first segment of microstrip lines, the second segment of microstrip lines, and the third segment of microstrip lines are connected in sequence, and the fourth segment of microstrip lines and the fifth segment of microstrip lines each have two places. The two places of the fourth segment of microstrip lines are connected with the third segment of microstrip lines to realize the one-to-two structure.

[0055] In Figure 3In the shown structure, the first section of microstrip line, the second section of microstrip line and the third section of microstrip line are located on the same straight line, the first end of the first section of microstrip line is connected to the input port, the second end is connected to the first end of the second section of microstrip line, the second end of the second section of microstrip line is connected to the first end of the third section of microstrip line, the second end of the third section of microstrip line is connected to the first end of two fourth sections of microstrip line, the second end of the two fourth sections of microstrip line is respectively connected to the first end of two fifth sections of microstrip line, and the second end of the fifth section of microstrip line is connected to the output port.

[0056] In the fifth section of microstrip line of the embodiment, the width gradually changes, and the main purpose is impedance transformation. A possible width gradient rule is as follows:

[0057] From the first section of microstrip line to the third section of microstrip line, the width gradually increases, and the corresponding characteristic impedance of the microstrip line gradually decreases;

[0058] The width of the fourth section of microstrip line is smaller than that of the third section, and the corresponding characteristic impedance of the microstrip line increases, so that the two fourth sections of microstrip line in the one-to-two structure are connected in parallel and matched with the third section of microstrip line in impedance; the second isolation resistor is connected between the two fourth sections of microstrip line;

[0059] The width of the fifth section of microstrip line is larger than that of the third section, and the corresponding characteristic impedance of the microstrip line decreases, so that the impedance matching with the one-to-two Wilkinson power divider A14 is realized.

[0060] In some embodiments of the present application, with reference to Figure 1 and Figure 4 The wideband omnidirectional tightly coupled antenna described in the present application further comprises: a curved truncated cone reflector 3. The curved truncated cone reflector 3 is composed of a truncated cone with a curved side surface, the upper bottom surface of the truncated cone has a diameter of L2, and the lower bottom surface has a diameter of L1. The curved surface is preferably a concave curved surface. The curved truncated cone reflector 3 has two, which are loaded on the upper side of the planar tightly coupled omnidirectional antenna array 1 and the lower side of the one-to-eight wideband Wilkinson power divider 2, respectively, and the area of the side close to the planar tightly coupled omnidirectional antenna array 1 is smaller than the area of the side away from the planar tightly coupled omnidirectional antenna array 1. The length from the lower bottom surface of the truncated cone to the planar tightly coupled omnidirectional antenna array 1 is H1.

[0061] In this embodiment, the side surface of the curved truncated cone reflector 3 is designed as a curved surface, which can optimize the radiation pattern of the ultra-wideband planar omnidirectional antenna and converge the energy radiated by the antenna to the horizontal direction. Through the design of the truncated cone, a structure with a curved side surface can be formed, which also supports the feeding structure of the antenna. Among the two curved truncated cone reflectors 3, the upper curved truncated cone reflector 3 converges the energy radiated by the ultra-wideband planar omnidirectional antenna to the horizontal direction, and the lower curved truncated cone reflector 3 converges the energy radiated by the ultra-wideband planar omnidirectional antenna to the horizontal direction.

[0062] In some embodiments of the present invention, the dielectric substrate of the planar tightly coupled omnidirectional antenna array 1 has a relative permittivity of 3.66 and a thickness of less than 1 mm. The dielectric substrate of the 1-to-8 broadband Wilkinson power divider 2 has a relative permittivity of 3.66 and a thickness of less than 1 mm. The dielectric substrate loaded between the planar tightly coupled omnidirectional antenna array 1 and the 1-to-8 broadband Wilkinson power divider 2 has a relative permittivity of 3 and a thickness of 3 mm.

[0063] In the embodiments described above, the portions printed on both sides of the dielectric substrate are made of metal.

[0064] To verify the effectiveness of the present invention, the specific dimensions of the antenna are further described, with the following values:

[0065] S d =8.7mm, W3=1.8mm, R3=22mm, W4=0.2mm, L b =6mm, R5=16mm, W2=1mm, R2=24.5mm,

[0066] W1 = 0.8 mm, R1 = 29.6 mm, S r =3.5mm, R4=12mm.

[0067] In the Wilkinson power divider B21 (1-to-2), the lengths of each microstrip line are as follows: first segment L4 = 3mm, second segment L5 = 3.5mm, third segment L6 = 3.8mm, fourth segment L7 = 3.05mm, and fifth segment L8 = 3.2mm. The widths of each microstrip line are as follows: first segment W5 = 0.1mm, second segment L6 = 0.2mm, third segment L7 = 0.4mm, fourth segment L8 = 0.2mm, and fifth segment L9 = 0.7mm.

[0068] In the curved frustum reflector 3, the diameter of the top surface of the frustum is L2 = 32 mm, the diameter of the bottom surface is L1 = 52 mm, and the length of the bottom surface of the frustum from the plane tightly coupled omnidirectional antenna array 1 is H1 = 17 mm. The material of the curved frustum reflector 3 is pure metal.

[0069] The technical effects of the present invention will be further explained below with reference to simulation experiments:

[0070] 1. Simulation conditions:

[0071] exist Figure 1 The overall structure of the present invention described herein was used to conduct simulation experiments on its performance in the 6GHz to 18GHz frequency band using commercial simulation software.

[0072] 2. Simulation content:

[0073] The active standing wave ratio of the input port of the above example is simulated by using commercial simulation software, and the result is shown in Figure 5 .

[0074] The directional diagram of the above example is simulated by using commercial simulation software, and the radiation directional diagram in the azimuth plane and the elevation plane at 6GHz, 12GHz and 18GHz is obtained, and the result is shown in Figure 6 , Figure 7

[0075] 3. Analysis of simulation result

[0076] Figure 5 In the figure, the horizontal coordinate represents the working frequency of the antenna array, and the vertical coordinate represents the active standing wave ratio of the antenna array. It can be seen from the figure that the impedance bandwidth of the antenna with an active standing wave ratio less than 3 is 6GHz-18GHz, and the wideband design of the antenna array is realized.

[0077] Figure 6 In the figure, the azimuth plane radiation directional diagram of the antenna at 6GHz, 12GHz and 18GHz is given, the left vertical coordinate is gain, the lower horizontal coordinate is phi angle, the black solid line represents the 6GHz azimuth plane radiation directional diagram, the black short dotted line represents the 12GHz azimuth plane radiation directional diagram, and the black dash line represents the 18GHz azimuth plane radiation directional diagram. The antenna has good non-circularity at 6GHz, 12GHz and 18GHz, and the non-circularity in the whole horizontal direction is less than 1dB, and the antenna has good omnidirectional radiation characteristics in the horizontal direction.

[0078] Figure 7 In the figure, the elevation plane radiation directional diagram of the antenna at 6GHz, 12GHz and 18GHz is given, the left vertical coordinate is gain, the lower horizontal coordinate is Theta angle, the black solid line represents the 6GHz azimuth plane radiation directional diagram, the black short dotted line represents the 12GHz azimuth plane radiation directional diagram, and the black dash line represents the 18GHz azimuth plane radiation directional diagram. The antenna has good beam width in the horizontal direction at 6GHz, 12GHz and 18GHz, and the gain is greater than -5dBi in the angle domain of elevation ±30°, and the antenna has good omnidirectional radiation characteristics in the horizontal direction.

[0079] Overall, the antenna has good wideband omnidirectional radiation characteristics, and the working frequency band, directional diagram and gain all have good characteristics. Compared with the prior art, the wideband, high gain, wide beam coverage, low non-circularity can be integrated into one antenna, and the antenna also has the characteristics of small size and easy integration, which can be better applied in more fields.​

Claims

1. A low-ovality ultra-wideband planar omni-directional antenna, characterized in that, The application relates to a one-to-eight broadband Wilkinson power divider (2) and a planar close-coupling omnidirectional antenna array (1); the planar close-coupling omnidirectional antenna array (1) comprises coupling-plate-loaded close-coupling dipoles (11), microstrip gradually-changing baluns (12), arc-shaped directors (13) and one-to-two Wilkinson power dividers A (14); The coupling-plate-loaded close-coupling dipoles (11) are in annular array distribution, each coupling-plate-loaded close-coupling dipole (11) is composed of a coupling plate and a dipole; wherein the coupling plate is printed on the upper side of a medium substrate, and the dipole is printed on the lower side of the medium substrate; The microstrip gradually-changing baluns (12) are in annular array distribution on the inner side of the coupling-plate-loaded close-coupling dipoles (11), the feed line and the ground plate of each microstrip gradually-changing balun (12) are connected with two dipoles of one coupling-plate-loaded close-coupling dipole (11) respectively; The arc-shaped directors (13) are in annular array distribution on the outer side of the coupling-plate-loaded close-coupling dipoles (11); the arc-shaped directors (13) are printed on the lower side of the medium substrate one; The one-to-two Wilkinson power dividers A (14) are in annular array distribution, each one-to-two Wilkinson power divider A (14) is connected with two microstrip gradually-changing baluns (12) and feeds the two microstrip gradually-changing baluns (12) with equal radiation and same phase; The number of the coupling-plate-loaded close-coupling dipoles (11) and the microstrip gradually-changing baluns (12) is the same, and the number of the coupling-plate-loaded close-coupling dipoles (11) is 2 times the number of the one-to-two Wilkinson power dividers A (14); the arc-shaped directors (13) have two layers, and the number of the layer close to the coupling-plate-loaded close-coupling dipoles (11) is 2 times the number of the microstrip gradually-changing baluns (12), and the number of the layer far from the coupling-plate-loaded close-coupling dipoles (11) is the same as the number of the microstrip gradually-changing baluns (12); The one-to-eight broadband Wilkinson power divider (2) is composed of four one-to-two Wilkinson power dividers B (21) in parallel connection; the feed line of the one-to-two Wilkinson power divider B (21) is printed on the lower side of a medium substrate two, and the ground plate is printed on the upper side of the medium substrate two; the output port of the one-to-eight broadband Wilkinson power divider (2) is connected with the input port of the one-to-two Wilkinson power divider A (14) through a metallized via, and the metallized via is located on a medium substrate three between the medium substrate one and the medium substrate two.

2. The low-ovality ultra-wideband planar omni-directional antenna according to claim 1, wherein, The microstrip tapered balun (12) adopts an exponential tapered curve, and a curve equation is wherein x is a horizontal width of the microstrip tapered balun (12), y is an extension length of the microstrip tapered balun (12), in millimeters.

3. The low- distortion ultra-wideband planar omni antenna according to claim 1, wherein, The number of the coupling patch loaded tight coupled dipoles (11) and the microstrip tapered baluns (12) is wherein S d L is the arc length of the coupling patch loaded tight coupled dipole (11), R 3 is the length of the coupling patch loaded tight coupled dipole (11) from the center of the circle, and [] is the rounding symbol.

4. The low- distortion ultra-wideband planar omni antenna according to claim 1, wherein, A first isolation resistor is loaded in the middle of each one-to-two Wilkinson power divider A (14) to ensure the isolation degree between the two output ports; a second isolation resistor is loaded in the middle of each one-to-two Wilkinson power divider B (21) to ensure the isolation degree between the two output ports.

5. The low- distortion ultra-wideband planar omni antenna according to claim 4, wherein, The resistance value of the first isolation resistor and the second isolation resistor is 100 ohm.

6. The low- distortion ultra-wideband planar omni antenna according to claim 1, wherein, The one-to-two Wilkinson power divider B (21) is composed of five microstrip lines with gradually-changing width and a second isolation resistor.

7. The low- distortion ultra-wideband planar omni antenna according to claim 6, wherein, The four one-to-two Wilkinson power dividers B (21) are in central symmetry distribution, the input port is located at the central symmetry center, and the width of the five microstrip lines of each one-to-two Wilkinson power divider B (21) gradually changes along the input port. The width of the first, second and third sections of the microstrip line increases in sequence, and the characteristic impedance of the corresponding microstrip line decreases in sequence; The width of the fourth section of the microstrip line is smaller than that of the third section, and the characteristic impedance of the corresponding microstrip line increases. The fourth section of the microstrip line is divided into two parts, which are connected with the third section of the microstrip line respectively, so as to realize impedance matching of the two fourth sections of the microstrip line in parallel with the third section of the microstrip line in the one-to-two structure; the second isolation resistor is connected between the two fourth sections of the microstrip line; The width of the fifth section of the microstrip line is larger than that of the third section, and the characteristic impedance of the corresponding microstrip line decreases, so as to realize impedance matching with the one-to-two Wilkinson power divider A (14).

8. A low-distortion ultra-wideband planar omni-directional antenna according to any one of claims 1 to 7, characterized in that, The low-irregularity ultra-wideband planar omnidirectional antenna further comprises: A curved truncated cone reflector (3); The curved truncated cone reflector (3) is composed of a truncated cone with a curved side surface, is loaded on the upper side of the planar tightly coupled omnidirectional antenna array (1) and the lower side of the one-to-eight broadband Wilkinson power divider (2) respectively, and the area of the side surface close to the planar tightly coupled omnidirectional antenna array (1) is smaller than the area of the side surface away from the planar tightly coupled omnidirectional antenna array (1).

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