A small horizontally polarized omnidirectional antenna

Abstract

The present invention belongs to the technical field of omnidirectional antennas, and discloses a small horizontally polarized omnidirectional antenna, including a microstrip board, wherein the microstrip board includes an upper microstrip board, a lower microstrip board, an intermediate insulating layer between the upper microstrip board and the lower microstrip board, and a coaxial connector. In this embodiment, the inner and outer conductors of the coaxial connector are respectively connected to the linear conductive strips of the upper and lower microstrip boards of the microstrip antenna, and the linear conductive strips of the upper and lower microstrip boards are respectively excited to produce a current. Since the characteristic of the coaxial connector is that the currents flowing on the inner and outer conductors are in opposite directions, currents in opposite directions are formed on the linear conductive strips of the upper and lower layers. When the current on the linear conductive strip reaches the annular conductive strip, since the annular conductive strip is in an annular structure and the two sides of the conductive strip are rotationally symmetrical, and the upper and lower annular conductive strips are mirror-imaged and one end is connected to the linear conductive strip, an annular current with the same direction is formed on the upper and lower microstrip boards, thereby forming an omnidirectional radiation pattern.

Description

Technical Field

[0001] The present invention belongs to the technical field of omnidirectional antennas and proposes a small horizontally polarized omnidirectional antenna. Background Art

[0002] Omnidirectional antennas have been widely used and studied in the fields of communication, reconnaissance and jamming. The typical implementation of a horizontally polarized omnidirectional antenna is to use a small circular ring antenna with a circumference smaller than the wavelength. Due to its working principle and structural characteristics, the small circular ring antenna can form a uniform current loop and a uniform radiation field around the ring, so it can form an omnidirectional pattern in the horizontal direction. However, due to its working principle and structural characteristics, the performance of the small circular ring antenna will drop rapidly when the frequency changes, so there is a problem of narrow impedance bandwidth, which makes it difficult to adapt to wide-band applications.

[0003] Another common way to realize horizontally polarized omnidirectional antennas is to use directional antennas evenly distributed along the circumference. Each directional antenna unit is designed to be horizontally polarized, and an equal power distribution network is used to form an equal amplitude and phase current distribution. This design method can ensure uniform radiation in all directions by adjusting the phase and amplitude of each antenna unit to obtain the desired horizontally polarized omnidirectional antenna. However, this method requires sufficient space to accommodate these directional antenna units distributed along the circumference, and has the problem of large lateral size, which limits its use in space-constrained applications. Summary of the invention

[0004] The purpose of this solution is to address the above-mentioned problem and provide a horizontally polarized omnidirectional antenna with a smaller lateral size and a wider bandwidth.

[0005] A small horizontally polarized omnidirectional antenna comprises a microstrip board, wherein the microstrip board comprises an upper microstrip board, a lower microstrip board, an intermediate insulating layer between the upper microstrip board and the lower microstrip board, and a coaxial connector;

[0006] The upper microstrip plate has a linear guide strip, and both sides of the linear guide strip are respectively provided with at least two annular guide strips, one end of which is connected to the linear guide strip; and the annular guide strips on both sides of the linear guide strip are rotationally symmetrical structures;

[0007] The lower microstrip plate has a conductive strip structure that is mirror-symmetrical to the upper microstrip plate;

[0008] The inner and outer conductors of the coaxial connector are respectively connected to the linear conductive strips of the upper microstrip plate and the lower microstrip plate.

[0009] In this scheme, the inner and outer conductors of the coaxial connector are respectively connected to the linear conductive strips of the upper microstrip board and the lower microstrip board of the microstrip antenna, and the linear conductive strips of the upper and lower microstrip boards are respectively excited to produce a current. Since the characteristic of the coaxial connector is that the currents flowing in the inner and outer conductors are in opposite directions, currents in opposite directions will be formed on the upper and lower linear conductive strips. When the current on the linear conductive strip reaches the annular conductive strip, since the annular conductive strip is annular in structure and the two sides of the conductive strip are rotationally symmetrical, the upper and lower annular conductive strips are mirror-imaged and one end is connected to the linear conductive strip, annular currents in the same direction will be formed on the upper and lower microstrip boards, thereby forming an omnidirectional radiation pattern.

[0010] The inner and outer conductors of the coaxial connector are connected to the parallel conductors of the upper and lower layers to form currents in opposite directions, and then form a circular current in the same direction after passing through the circular conductor.

[0011] The above-mentioned small horizontally polarized omnidirectional antenna also includes a bottom plate, and the microstrip plate is supported on the bottom plate by at least three dielectric rods.

[0012] In the above-mentioned small horizontally polarized omnidirectional antenna, the distance between the microstrip plate and the bottom plate is 35mm-60mm;

[0013] The microstrip board is supported on the bottom plate by four dielectric rods.

[0014] In the above-mentioned small horizontally polarized omnidirectional antenna, the inner conductor of the coaxial connector is connected to the linear conductive strip of the upper microstrip board, and the outer conductor is connected to the linear conductive strip of the lower microstrip board;

[0015] Alternatively, the inner conductor of the coaxial connector is connected to the linear conductive strip of the lower microstrip board, and the outer conductor is connected to the linear conductive strip of the upper microstrip board. The base of the coaxial connector is mounted on the dielectric bottom plate.

[0016] In the above-mentioned small horizontally polarized omnidirectional antenna, the thickness of the upper microstrip plate and the lower microstrip plate are both 0.1mm-0.2mm;

[0017] The thickness of the intermediate insulating layer is 1 mm-3 mm.

[0018] The different thicknesses of the upper and lower microstrip plates and the middle insulating layer will affect the standing wave ratio and bandwidth of the antenna. The above thicknesses can achieve a better antenna standing wave ratio and a wider bandwidth.

[0019] In the above-mentioned small horizontally polarized omnidirectional antenna, the thickness of the upper microstrip plate and the lower microstrip plate are both 0.168 mm;

[0020] The thickness of the intermediate insulating layer is 2 mm.

[0021] In the above-mentioned small horizontally polarized omnidirectional antenna, the surfaces of the upper microstrip plate and the lower microstrip plate are both circular structures, the upper microstrip plate and the lower microstrip plate are equal in size, and the centers of the microstrip plates are located on the same axis;

[0022] The linear guide strip is a linear guide strip passing through the center of the microstrip plate, and the center of each annular guide strip is located on the same axis as the center of the microstrip plate.

[0023] In the above-mentioned small horizontally polarized omnidirectional antenna, the diameters of the upper microstrip plate and the lower microstrip plate are 0.0933λ±10mm, where λ is the minimum operating wavelength of the antenna;

[0024] The annular guide belts on both sides of the linear guide belt have the same center, and the annular guide belts on the same side of the linear guide belt have different radii;

[0025] The two sides of the linear guide belt are respectively provided with three annular guide belts, one end of which is connected to the linear guide belt;

[0026] The curvature of each annular guide belt is 170°±10° and less than 180°. The curvature of each annular guide belt is equal or unequal, such as all 172°, or one is 170°, one is 168°, one is 175°, etc.

[0027] The radii of the three annular guide strips are, respectively, r-(0.1mm~5mm), (3r / 4)±5mm, (r / 2)±5mm, where r represents the radius of the microstrip plate.

[0028] In the above-mentioned small horizontally polarized omnidirectional antenna, the width of the linear conductive strip is 2 mm-3 mm, and the width of the annular conductive strip is 1 mm-1.5 mm;

[0029] A first resistor, a second resistor, a third resistor and a fourth resistor are respectively arranged at positions of 115°±5°, 128°±5°, 142°±5° and 158°±5° of each annular guide band.

[0030] The above annular guide band radius, curvature and resistors set at corresponding positions can achieve a better antenna standing wave ratio and a wider bandwidth. The advantages of this solution are:

[0031] (1) The conductive strip structure of this scheme is composed of a rotationally symmetrical annular conductive strip and a linear conductive strip. The microstrip board is composed of two layers, the upper and lower layers. By making the conductive strip structures of the upper and lower layers of the microstrip board mirror-symmetrical and utilizing coaxial connectors, a uniform annular current is achieved on the microstrip board, thereby forming a good horizontally polarized omnidirectional radiation pattern. At the same time, this scheme designs three rotationally symmetrical annular conductive strips on each layer of the microstrip board, and sets multiple resistors on the annular conductive strips. By making the outermost circle mainly work in the low frequency band and the innermost circle mainly work in the high frequency band, different circles correspond to different working frequencies to achieve a wide bandwidth effect.

[0032] (2) The minimum lateral electrical dimension of a general horizontally polarized omnidirectional antenna can only be λ / 5. The antenna structure implemented by this scheme has been proven through experiments that an antenna diameter of about 0.0933λ can have the impedance matching capability and wide bandwidth effect of a conventional antenna with an antenna diameter of λ / 5. From the standing wave of 200MHz-400MHz, it can be seen that the bandwidth of the antenna structure provided by this scheme can reach more than 67%. Compared with conventional antennas, it has a smaller lateral electrical dimension and can meet the requirements of miniaturization and wide bandwidth of horizontally polarized omnidirectional antennas. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the structure of a horizontally polarized omnidirectional antenna;

[0034] Figure 2 It is a front view schematic diagram of a horizontally polarized omnidirectional antenna;

[0035] Figure 3 It is a schematic diagram of the back side of the horizontally polarized omnidirectional antenna;

[0036] Figure 4 is a side schematic diagram of a horizontally polarized omnidirectional antenna;

[0037] Figure 5 Antenna standing wave diagram of the horizontally polarized omnidirectional antenna provided in this solution;

[0038] Figure 6 The horizontal plane radiation pattern of the typical frequency points of the horizontally polarized omnidirectional antenna provided in this solution.

[0039] Description of the drawings: upper microstrip board 1; lower microstrip board 14; middle insulating layer 2; annular conductive strip 3; linear conductive strip 4; dielectric rod 5; bottom plate 6; coaxial connector 7; first resistor 81; second resistor 82; third resistor 83; fourth resistor 84. DETAILED DESCRIPTION

[0040] The present solution is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0041] This embodiment realizes a horizontally polarized omnidirectional antenna with a minimum operating wavelength λ of about 1500 mm and an operating center frequency of about 300 MHz, and verifies the antenna standing wave and azimuth plane direction.

[0042] like Figure 1As shown, firstly, the diameter of the microstrip board is determined according to the working frequency band of the antenna, and here it is 140 mm. The microstrip board is divided into two layers, an upper microstrip board 1 and a lower microstrip board 14. A foam layer as a dielectric material is provided between the upper microstrip board 1 and the lower microstrip board 14, that is, an intermediate insulating layer 2. In this embodiment, the thickness of the upper microstrip board 1 and the lower microstrip board 14 are both 0.168 mm, the dielectric constant is 3.66, and the thickness of the intermediate foam layer is 2 mm.

[0043] The surfaces of the upper microstrip plate 1 and the lower microstrip plate 14 are both circular structures. The upper microstrip plate 1 and the lower microstrip plate 14 are equal in size and are arranged opposite to each other. The diameters of the upper microstrip plate 1 and the lower microstrip plate 14 are both about 140 mm. The centers of the circles of the upper microstrip plate 1 and the lower microstrip plate 14 are located on the same axis. Figure 2 and Figure 3 As shown, the upper microstrip plate 1 and the lower microstrip plate 14 have a conduction strip structure in a mirror-symmetrical relationship. Specifically, the upper microstrip plate 1 and the lower microstrip plate 14 are respectively etched with a straight conduction strip 4 passing through the center of the microstrip plate as a feed line, with a length of about 140 mm, which is equal to or slightly smaller than the diameter of the microstrip plate, and the width of the straight conduction strip 4 is about 2.5 mm. Three annular conduction strips 3 are etched on both sides of the straight conduction strip 4, one end of which is connected to the straight conduction strip 4, and the annular conduction strips 3 on both sides of the straight conduction strip 4 are rotationally symmetrical structures, the six annular conduction strips 3 have the same center, and the three annular conduction strips 3 on the same side of the straight conduction strip 4 have different radii, and a uniform circular current is achieved through the upper and lower layers of conduction strips. The conduction strip structure of the upper microstrip plate 1 is located on the side away from the lower microstrip plate 14, that is, the upper surface, and the conduction strip structure of the lower microstrip plate 14 is located on the side away from the upper microstrip plate 1, that is, the lower surface.

[0044] Specifically, the curvature of the annular guide belt 3 is 175°, the radii of the three annular guide belts 3 on one side are arcs of 30 mm, 55 mm, and 69 mm respectively, the width of the guide belts is 1.3 mm, and the other side is rotationally symmetrical.

[0045] The thickness of the upper microstrip plate 1 and the lower microstrip plate 14, the thickness of the middle foam layer, the curvature of the annular guide strip, and the width of the guide strip will have an impact on the standing wave ratio and bandwidth of the antenna. In this embodiment, the width of the linear guide strip 4 and the annular guide strip 3 are 2.5mm and 1.3mm respectively, the curvature of the annular guide strip is 175°, the thickness of the upper microstrip plate 1 and the lower microstrip plate 14 is 0.168mm, and the thickness of the middle foam layer is 2mm. When put into use, the linear guide strip 4 can be 2mm-3mm, the width of the annular guide strip 3 can be 1mm-1.5mm, the curvature of the annular guide strip 3 can be 170°±10°, the thickness of the upper microstrip plate 1 and the lower microstrip plate 14 can be 0.1mm-0.2mm, and the thickness of the middle insulating layer 2 can be 1mm-3mm. Within this range, the provided antenna structure can achieve a better standing wave ratio and a wider bandwidth.

[0046] On the annular guide belt 3, the positions of 115°, 128°, 142°, and 158° from one end connected to the linear guide belt 4 are respectively placed as follows Figure 2 The first resistor 81, the second resistor 82, the third resistor 83, and the fourth resistor 84 are shown, and the first resistor 81, the second resistor 82, the third resistor 83, and the fourth resistor 84 are 200Ω, 400Ω, 800Ω, and 1200Ω, respectively, that is, four resistors are set at the end of the annular conductive strip 3 close to the end not connected to the linear conductive strip 4 to achieve impedance matching. This example provides an implementation method. When put into use, the first resistor 81, the second resistor 82, the third resistor 83, and the fourth resistor 84 can be set at the positions of 115°±5°, 128°±5°, 142°±5°, and 158°±5° of the annular conductive strip, respectively. The angle position of the resistors on each annular conductive strip can be the same or different.

[0047] like Figure 3 As shown, the structure and size of the conductive strip on the lower microstrip board 14 and the distribution and size of the resistance are the same as those of the upper microstrip board 1, forming a mirror-symmetric relationship. The inner and outer conductors of the feeding coaxial connector 7 are respectively welded to the middle position of the two straight conductive strips 4 of the upper microstrip board 1 and the lower microstrip board 14, so that the inner and outer conductors respectively form currents in opposite directions with the straight conductive strips 4 of the upper microstrip board 1 and the lower microstrip board 14, and form a circular current in the same direction after passing through the circular conductive strip 3.

[0048] like Figure 4 As shown, the base of the coaxial connector 7 is installed on the dielectric base plate 6, and the entire microstrip board is supported on the dielectric base plate 6 by four dielectric rods 5. The four dielectric rods 5 are 90 degrees apart and respectively connect the microstrip board and the base plate 6 to play a supporting and fixing role. The microstrip board and the base plate 6 are about 50 mm apart.

[0049] Through the above means, a horizontally polarized omnidirectional antenna with a minimum operating wavelength λ of about 1500mm and an operating center frequency of about 300MHz is obtained. The standing wave diagram obtained by testing it is as follows Figure 5 As shown, the horizontal plane direction diagram is as follows Figure 6 As shown. Figure 5 It can be seen that the standing wave ratio is less than 2 in the range of 200MHz-400MHz, and the working center frequency of the antenna is 300MHz, so the bandwidth can be as high as 67% or more, which is a breakthrough for horizontally polarized omnidirectional antennas. Figure 6It can be seen that the horizontally polarized omnidirectional antenna implemented in this embodiment has good omnidirectionality and meets the omnidirectional requirements of the antenna. In addition, the diameter of the implemented antenna is only 140 mm. Therefore, the structure provided by this solution can realize a horizontally polarized omnidirectional antenna with a smaller lateral size while ensuring a wider bandwidth. The specific embodiments described in this article are merely examples of the spirit of this solution. Technicians in the technical field to which this solution belongs can make various modifications or supplements to the specific embodiments described or replace them in a similar manner, but they will not deviate from the spirit of this solution or exceed the scope defined by the attached claims.

[0050] Although the present invention generally uses the terms such as upper microstrip board 1; lower microstrip board 14; middle insulating layer 2; annular conductive strip 3; linear conductive strip 4; dielectric rod 5; bottom plate 6; coaxial connector 7; first resistor 81, second resistor 82, third resistor 83, fourth resistor 84, etc., it does not exclude the possibility of using other terms. These terms are used only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional limitation is contrary to the spirit of the present invention.

Claims

1. A small horizontally polarized omnidirectional antenna, characterized in that: The microstrip board comprises an upper microstrip board (1), a lower microstrip board (14), an intermediate insulating layer (2) between the upper microstrip board (1) and the lower microstrip board (14), and a coaxial connector (7); the thickness of the upper microstrip board (1) and the lower microstrip board (14) are both 0.1 mm to 0.2 mm; the thickness of the intermediate insulating layer (2) is 1 mm to 3 mm; The upper microstrip plate (1) has a straight conductive strip (4), and the two sides of the straight conductive strip (4) respectively have three annular conductive strips (3) with one end connected to the straight conductive strip (4); and the annular conductive strips (3) on the two sides of the straight conductive strip (4) are rotationally symmetrical structures; The lower microstrip plate (14) has a conductive strip structure that is mirror-symmetrical to the upper microstrip plate (1); The inner and outer conductors of the coaxial connector (7) are respectively connected to the linear conductive strips (4) of the upper microstrip plate (1) and the lower microstrip plate (14); The surfaces of the upper microstrip plate (1) and the lower microstrip plate (14) are both circular structures, and the diameters of the upper microstrip plate (1) and the lower microstrip plate (14) are 0.0933λ±10mm, the centers of the circles are located on the same axis, and λ is the minimum operating wavelength of the antenna; The curvature of each annular guide strip (3) is 170°±10° and less than 180°. The radii of the three annular guide strips (3) are, respectively, r-(0.1 mm~5 mm), (3r / 4)±5 mm, (r / 2)±5 mm, where r represents the radius of the microstrip plate. The width of the linear guide belt (4) is 2 mm to 3 mm, and the width of the annular guide belt (3) is 1 mm to 1.5 mm; A first resistor (81), a second resistor (82), a third resistor (83), and a fourth resistor (84) are respectively arranged at positions of 115°±5°, 128°±5°, 142°±5°, and 158°±5° of each annular conductive strip (3).

2. The small horizontally polarized omnidirectional antenna according to claim 1, characterized in that: It also includes a base plate (6), and the microstrip plate is supported on the base plate (6) via at least three dielectric rods (5).

3. The small horizontally polarized omnidirectional antenna according to claim 2, characterized in that: The distance between the microstrip plate and the base plate (6) is 35 mm to 60 mm; The microstrip plate is supported on the base plate (6) via four dielectric rods (5).

4. The small horizontally polarized omnidirectional antenna according to any one of claims 1 to 3, characterized in that: The inner conductor of the coaxial connector (7) is connected to the straight conductive strip (4) of the upper microstrip plate (1), and the outer conductor is connected to the straight conductive strip (4) of the lower microstrip plate (14); Alternatively, the inner conductor of the coaxial connector (7) is connected to the linear conductive strip (4) of the lower microstrip plate (14), and the outer conductor is connected to the linear conductive strip (4) of the upper microstrip plate (1).

5. The small horizontally polarized omnidirectional antenna according to claim 1, characterized in that: The thickness of the upper microstrip plate (1) and the lower microstrip plate (14) are both 0.168 mm; The thickness of the intermediate insulating layer (2) is 2 mm.

6. The small horizontally polarized omnidirectional antenna according to claim 4, characterized in that: The linear guide strip (4) is a linear guide strip passing through the center of the microstrip plate, and the center of each annular guide strip (3) and the center of the microstrip plate are located on the same axis; The annular guide belts (3) on both sides of the linear guide belt (4) have the same center of circle, and the annular guide belts (3) located on the same side of the linear guide belt (4) have different radii.

7. The small horizontally polarized omnidirectional antenna according to claim 6, characterized in that: The curvatures of the annular guide belts (3) are equal or unequal.

8. The small horizontally polarized omnidirectional antenna according to claim 4, characterized in that: The resistance values ​​of the first resistor 81 , the second resistor 82 , the third resistor 83 , and the fourth resistor 84 are 200Ω, 400Ω, 800Ω, and 1200Ω respectively.

9. The small horizontally polarized omnidirectional antenna according to claim 4, characterized in that: The working frequency of this antenna is 200MHz~400MHz, and the working center frequency is 300MHz.

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