Compact ultra-wideband directional helical antenna

Abstract

The utility model provides a compact ultra-wideband directional helical antenna, which comprises a first radiation layer and a second reflection metal structure, and is characterized in that the first radiation layer comprises a first helical microstrip line, a second helical microstrip line, a gradient feed microstrip line, an annular microstrip structure and a medium; the second layer of reflection metal structure is composed of two L-shaped metal branches and a metal plane with four step-shaped openings. The antenna is manufactured by adopting a two-layer structure, only one layer of FR4 material and one metal reflector are used, directional radiation is realized, a feed balun structure is not introduced, the profile of the antenna is effectively reduced, and the manufacturing cost is low; compared with a three-dimensional helical antenna and a multi-layer planar helical antenna, the antenna provided by the utility model is compact in structure, is simple in installation steps, and is low in material cost.

Description

Technical Field

[0001] The utility model relates to the technical field of ultra-wideband antennas, and particularly relates to a compact ultra-wideband directional spiral antenna. Background Art

[0002] In recent years, the UWB (Ultra-Wide-Band) ultra-wideband wireless carrier communication technology has become increasingly mature. Its communication distance and positioning accuracy have been continuously improved, and it has the characteristics of low cost, high positioning accuracy, and little external interference. It has gradually shown the application potential of UWB in indoor and outdoor positioning. Especially in the applications of navigating and positioning agricultural machinery through UWB positioning technology, and positioning high-speed objects. As a core component inside the ultra-wideband communication system, the performance of the antenna will directly affect the quality of the communication system. Facing a complex environment, especially in complex environments with a lot of rain, fog, humidity, and hills, traditional ultra-wideband linear polarization antennas are difficult to maintain good performance in such an environment. In a communication system, compared with linear polarization antennas, circular polarization antennas can overcome problems such as polarization mismatch, multipath attenuation, and signal crosstalk during signal transmission.

[0003] However, most of the existing ultra-wideband spiral antennas on the market have bi-directional radiation and low gain, which is not conducive to the application of the communication system. Ultra-wideband directional spiral antennas have become a popular product due to their high gain and ultra-wideband circular polarization radiation. Currently, the general characteristics of directional spiral antennas are large volume, complex structure, and high antenna manufacturing cost; there are two forms of ultra-wideband directional spiral antennas. One is a three-dimensional structure spiral antenna, such as a four-wall spiral antenna, which uses a three-dimensional structure spiral microstrip line as the radiator and requires designing a corresponding feeding network to feed it. Although it can obtain directional ultra-wideband circular polarization radiation, this kind of antenna is often large in size, complex in structure, and high in manufacturing cost. The other is a planar spiral antenna, which uses a planar spiral microstrip line as the radiator and requires designing a corresponding feeding balun. Due to the existence of the feeding balun, this kind of antenna has a higher profile, which is not conducive to system integration, and the balun will also increase the manufacturing cost of the antenna. Summary of the Utility Model

[0004] Aiming at the above defects in the prior art, the utility model aims to provide a compact ultra-wideband directional spiral antenna. A compact ultra-wideband directional spiral antenna is provided, which is made of a two-layer structure, only uses one layer of FR4 material and a metal reflector to achieve directional radiation. The utility model does not introduce a feeding balun structure, effectively reducing the profile of the antenna and having a low manufacturing cost; compared with three-dimensional spiral antennas and multi-layer planar spiral antennas, the utility model has the characteristics of a compact structure, simple installation steps, and less material cost.

[0005] In the first aspect, the utility model provides a compact ultra-wideband directional spiral antenna, mainly including:

[0006] The first layer radiation layer and the second layer reflection metal structure;

[0007] The first layer radiation layer includes a first spiral microstrip line, a second spiral microstrip line, a tapered feeding microstrip line, a circular ring microstrip structure and a dielectric;

[0008] The second layer reflection metal structure is composed of two "L"-shaped metal branches and a metal plane;

[0009] Wherein, the first spiral microstrip line and the second spiral microstrip line form a spiral antenna which is correspondingly and staggeredly distributed on the upper and lower surfaces of the dielectric with the same spiral center as the reference; at the spiral center, the tapered feeding microstrip line is used as a feeding structure to perform impedance matching between the coaxial line and the spiral line; the second layer reflection metal structure cooperates with the spiral antenna to realize signal directional radiation, and the ends of the two "L"-shaped metal branches are connected to the ends of the first spiral microstrip line and the second spiral microstrip line to realize an ultra-wide circular polarization bandwidth.

[0010] In the present utility model, the two "L"-shaped metal branches are located at the two side edges of the metal plane and are integrally formed with the metal plane;

[0011] The two "L"-shaped metal branches are symmetrically distributed along the spiral center point, are located on the same plane, and are higher than the metal plane.

[0012] A stepped opening is provided at the four vertex positions of the metal plane to increase the circular polarization bandwidth.

[0013] Four plastic columns are provided at the stepped opening position for fixing the dielectric; the height of the plastic columns is 14 mm;

[0014] The height of the plastic columns is the distance between the metal plane and the two "L"-shaped metal branches. The ends of the two spiral microstrip lines and the ends of the "L"-shaped metal branches are connected by metal columns; the circular ring microstrip structure is arranged on the upper surface of the dielectric corresponding to the end of the second spiral microstrip line, so that the metal columns are tightly connected to the second spiral strip line.

[0015] The tapered feeding microstrip line is fed by a GB405 coaxial line;

[0016] The GB405 coaxial line penetrates through the reflection metal structure, and the outer conductor of the coaxial line is connected to the reflection metal structure by a metal flange;

[0017] The grounding end of the GB405 coaxial line is welded to the second spiral microstrip line;

[0018] The inner core of the GB405 coaxial line is welded to the tapered feeding microstrip line.

[0019] The first spiral microstrip line is connected to the end of the tapered feeding microstrip line.

[0020] The first spiral microstrip line and the second spiral microstrip line are respectively arranged on the upper and lower surfaces of the dielectric substrate.

[0021] The first spiral microstrip line and the second spiral microstrip line have 2 turns, a width of 4.5 mm, and a dielectric thickness of 1 mm.

[0022] The maximum width of the tapered feeding microstrip line is 0.97 mm, the minimum width is 0.38 mm, and the number of turns is 1 turn.

[0023] The inner diameter of the circular ring microstrip structure is 2 mm and the outer diameter is 5 mm.

[0024] The thickness of the two "L"-shaped metal branches is 1 mm; the lengths of the two arms are 12.5 mm and 30 mm respectively.

[0025] The metal plane is a square with a side length of 55 mm and a thickness of 1 mm;

[0026] The widths of the stepped openings are 1.5 mm and 4.5 mm respectively, and the lengths are 6.5 mm and 4.5 mm respectively.

[0027] Compared with the prior art, the present utility model has at least the following beneficial effects:

[0028] The spiral ultra-wideband directional spiral antenna of the present utility model is a compact ultra-wideband directional spiral antenna. In order to achieve a wider circular polarization bandwidth, "L"-shaped metal branches are added to the reflecting surface of the second layer. Connecting the end of the "L"-shaped branch to the end of the spiral strip line can effectively broaden the circular polarization radiation bandwidth and achieve ultra-wideband directional circular polarization radiation without increasing the height of the antenna.

[0029] In order to further broaden the circular polarization bandwidth of the compact ultra-wideband directional spiral antenna of the present utility model, four stepped slots are added around the reflecting surface. These four slots can adjust the circular polarization mode of the antenna and effectively improve the circular polarization bandwidth. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic three-dimensional structure diagram of a compact ultra-wideband directional spiral antenna in an embodiment of the present utility model.

[0031] Figure 2 It is a schematic diagram of the upper surface of the radiation layer of the compact ultra-wideband directional spiral antenna in an embodiment of the present utility model.

[0032] Figure 3 It is a schematic diagram of the lower surface of the radiation layer of the compact ultra-wideband directional spiral antenna in an embodiment of the present utility model.

[0033] Figure 4 This is the reflective metal layer 8 of the compact ultra-wideband directional spiral antenna in the embodiment of the present application.

[0034] Figure 5 This is the reflection coefficient curve obtained by simulating the compact ultra-wideband directional spiral antenna in the embodiment of the present utility model.

[0035] Figure 6 This is the axial ratio curve obtained by simulating the compact ultra-wideband directional spiral antenna in the embodiment of the present utility model.

[0036] Figure 7 This is the simulated gain curve of the compact ultra-wideband directional spiral antenna in the embodiment of the present utility model.

[0037] Figure 8 (a) This is the xoz radiation pattern of the compact ultra-wideband directional spiral antenna at 3.2 GHz in the embodiment of the present application.

[0038] Figure 8 (b) This is the yoz radiation pattern of the compact ultra-wideband directional spiral antenna at 3.2 GHz in the embodiment of the present application.

[0039] Figure 9 (a) This is the xoz radiation pattern of the compact ultra-wideband directional spiral antenna at 4.5 GHz in the embodiment of the present application.

[0040] Figure 9 (b) This is the yoz radiation pattern of the compact ultra-wideband directional spiral antenna at 4.5 GHz in the embodiment of the present application.

[0041] Figure 10 (a) This is the xoz radiation pattern of the compact ultra-wideband directional spiral antenna at 5.5 GHz in the embodiment of the present application.

[0042] Figure 10 (b) This is the yoz radiation pattern of the compact ultra-wideband directional spiral antenna at 5.5 GHz in the embodiment of the present application.

[0043] Among them, 1 - the first radiation layer; 2 - the first spiral microstrip line; 3 - the second spiral microstrip line; 4 - the tapered feeding microstrip line; 5 - the inner core; 6 - the metal column; 7 - the circular ring microstrip structure; 8 - the metal plane; 9 - the "L"-shaped metal branch; 10 - the stepped opening; 11 - the plastic column; 12 - the GB405 coaxial cable; 13 - the metal flange. Detailed implementation manners

[0044] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0045] Embodiment 1:

[0046] Please refer to the attached Figure 1 , Figure 1 which is a three-dimensional structural schematic diagram of the compact ultra-wideband directional spiral antenna provided by the embodiment of the present invention.

[0047] The present invention provides a compact ultra-wideband directional spiral antenna, which can obtain ultra-wideband directional circular polarization radiation, has a compact structure, and a low manufacturing cost. The compact ultra-wideband directional spiral antenna of the present invention includes two layers of structures, namely: the first layer is a radiation structure, and the second layer is a reflection metal structure. The radiation structure includes a dielectric, with symmetric spiral microstrip structures arranged on the upper and lower surfaces, a spiral tapered microstrip line arranged at the center of the dielectric, and a circular ring microstrip structure arranged on the upper surface of the dielectric;

[0048] The second layer is a reflection metal structure, which is composed of two "L"-shaped metal branches and a square metal surface with four stepped slits cut off. The two "L"-shaped metal microstrip branches in the second layer are connected to the spiral strip line in the first layer by metal posts, and the two-layer structure is fixed by nylon posts.

[0049] In order to achieve a wider circular polarization bandwidth, the compact ultra-wideband directional spiral antenna of the present invention adds "L"-shaped metal branches to the reflection surface of the second layer. Connecting the ends of the "L"-shaped branches to the ends of the spiral strip line can effectively broaden the circular polarization radiation bandwidth and achieve ultra-wideband directional circular polarization radiation without increasing the height of the antenna.

[0050] In the present invention, the two "L"-shaped metal branches are located at the two side edges of the metal plane and are integrally formed with the metal plane;

[0051] The two "L"-shaped metal branches are symmetrically distributed along the spiral center point, are located on the same plane, and are higher than the metal plane.

[0052] A stepped opening is provided at the four vertex positions of the metal plane to increase the circular polarization bandwidth.

[0053] Four plastic posts are provided at the stepped opening position to fix the dielectric; the height of the plastic posts is 14 mm;

[0054] The height of the plastic column is the distance between the metal plane and the two "L"-shaped metal branches. The ends of the two spiral microstrip lines are connected to the ends of the "L"-shaped metal branches through metal columns; the circular-ring microstrip structure is arranged on the upper surface of the dielectric corresponding to the end of the second spiral microstrip line, so that the metal column is tightly connected to the second spiral strip line.

[0055] The tapered feed microstrip line is fed by a GB405 coaxial cable;

[0056] The GB405 coaxial cable passes through the second-layer reflection structure, and the outer conductor is connected to the second-layer reflection structure by a metal flange;

[0057] The grounding end of the GB405 coaxial cable is welded to the second spiral microstrip line;

[0058] The inner core of the GB405 coaxial cable is welded to the tapered feed microstrip line.

[0059] The first spiral microstrip line is connected to the end of the tapered feed microstrip line.

[0060] The first spiral microstrip line and the second spiral microstrip line are arranged on the upper and lower surfaces of the dielectric.

[0061] The first spiral microstrip line and the second spiral microstrip line have 2 turns, a width of 4.5 mm, and the dielectric has a thickness of 1 mm.

[0062] The maximum width of the tapered feed microstrip line is 0.97 mm, the minimum width is 0.38 mm, and the number of turns is 1.

[0063] The thickness of the two "L"-shaped metal branches is 1 mm; the lengths of the two arms are 12.5 mm and 30 mm respectively.

[0064] The metal plane is a square with a side length of 55 mm and a thickness of 1 mm;

[0065] The widths of the stepped openings are 1.5 and 4.5 mm respectively, and the lengths are 6.5 mm and 4.5 mm respectively.

[0066] The inner diameter of the circular-ring microstrip structure is 2 mm and the outer diameter is 5 mm.

[0067] The utility model adopts a symmetrical spiral strip line as the radiation structure, and a tapered microstrip line as the feeding structure at the center of the spiral line to match the impedance between the coaxial line and the spiral line; the second layer is a metal reflection metal structure, enabling the spiral antenna to achieve directional radiation. The "L"-shaped metal branches of the second layer are connected to the ends of the two spiral strip lines of the first layer, realizing ultra-wideband circular polarization radiation; the first layer of spiral strip line and the second layer of reflection metal structure are connected by metal posts. The antenna is fed by a GB405 coaxial line. The coaxial line passes through the reflection metal structure. The outer conductor of the coaxial line is connected to the metal reflection metal structure by a metal flange and welded to the second spiral microstrip line of the radiation layer. Its inner core is welded to the tapered feeder line on the upper surface of the radiation layer, so that the antenna has better impedance matching, thereby obtaining a wider impedance bandwidth without increasing the antenna profile height; four stepped slots are arranged around the second layer of reflection metal structure to increase the circular polarization bandwidth.

[0068] Figure 1 FIG. is a schematic three-dimensional structure diagram of a compact ultra-wideband directional spiral antenna in a preferred embodiment of the present invention. The spiral antenna includes a first-layer radiation structure 1 and a second-layer reflection surface structure 8. The first-layer radiation layer is composed of spiral microstrip lines 2, 3 and a tapered feeding microstrip line 4. The second-layer reflection metal structure is composed of two "L"-shaped metal branches 9 and a metal plane with four stepped slots 10. The first-layer radiation structure and the second-layer reflection surface structure are connected by 2 metal posts 6, and the two layers are fixed by four plastic posts 11.

[0069] Figure 2 and Figure 3 FIGS. are the upper and lower surfaces of the radiation layer of the compact ultra-wideband directional spiral antenna. The main radiators are the spiral microstrip line 2 and the spiral microstrip line 3. In order to obtain a wider impedance bandwidth, a tapered microstrip feeder line is used in the middle. The antenna is directly fed by welding a coaxial cable. Its inner core 5 is connected to the tapered strip line 4 on the upper surface of the radiation layer. Since the radio frequency current flows along the direction of the spiral strip line of the radiation layer, circular polarization radiation can be generated. In order not to increase the profile height, a tapered microstrip line is used as the feeder line. In order to obtain directional radiation characteristics, the present invention provides a metal reflection surface below the radiation layer. The ends of the spiral microstrip lines are connected and fixed to the "L"-shaped branches of the emitting surface through two metal posts 6.

[0070] Figure 4It is the reflective metal layer 8 of the compact ultra-wideband directional spiral antenna. This reflective metal structure has an "L"-shaped metal stub 9 and four stepped slots 10. The reflective metal structure is connected to the spiral strip line of the radiation layer through the "L"-shaped stub, which can effectively expand the circular polarization bandwidth and achieve ultra-wideband circular polarization radiation. Without increasing the antenna size, it weakens the influence of the horizontal metal reflector on the spiral antenna and effectively reduces the antenna size. The reflective metal structure is connected to the outer conductor of the GB405 coaxial feeder 12 and fixed with a metal flange. Adding four stepped slots around the horizontal reflector can effectively optimize the circular polarization radiation of the antenna and further broaden the circular polarization bandwidth.

[0071] Figure 5 and Figure 6 are respectively the reflection coefficient curve and the axial ratio curve obtained by simulating the compact ultra-wideband directional spiral antenna of the present invention. As shown in the figure, this compact ultra-wideband directional spiral antenna has a very wide impedance bandwidth and circular polarization bandwidth. The impedance bandwidth can reach 81.4% (3.16 - 7.5 GHz), while the 3dB axial ratio bandwidth is 66.2% (3.06 - 6.09 GHz). Figure 7 is the simulated gain curve of the compact ultra-wideband directional spiral antenna of the present invention. It can be seen from the figure that the gain is relatively stable within the axial ratio bandwidth, and the highest gain obtained reaches 7.3 dBic.

[0072] Figure 4 It is the reflective metal layer 8 of the compact ultra-wideband directional spiral antenna. This reflective metal structure has an "L"-shaped metal stub 9 and four stepped slots 10. The reflective metal structure is connected to the spiral strip line of the radiation layer through the "L"-shaped stub, which can effectively expand the circular polarization bandwidth and achieve ultra-wideband circular polarization radiation. Without increasing the antenna size, it weakens the influence of the horizontal metal reflector on the spiral antenna and effectively reduces the antenna size. The reflective metal structure is connected to the outer conductor of the GB405 coaxial feeder 12 and fixed with a metal flange. Adding four stepped slots around the horizontal reflector can effectively optimize the circular polarization radiation of the antenna and further broaden the circular polarization bandwidth.

[0073] Figure 5 and Figure 6 are respectively the reflection coefficient curve and the axial ratio curve obtained by simulating the compact ultra-wideband directional spiral antenna of the present invention. As shown in the figure, this compact ultra-wideband directional spiral antenna has a very wide impedance bandwidth and circular polarization bandwidth. The impedance bandwidth can reach 81.4% (3.16 - 7.5 GHz), while the 3dB axial ratio bandwidth is 66.2% (3.06 - 6.09 GHz). Figure 7 is the simulated gain curve of the compact ultra-wideband directional spiral antenna of the present invention. It can be seen from the figure that the gain is relatively stable within the axial ratio bandwidth, and the highest gain obtained reaches 7.3 dBic.

[0074] Furthermore, the compact ultra-wideband directional spiral antenna of the present invention requires 4 plastic posts 11 for assembly and installation. The 4 plastic posts are installed around the first-layer radiator and the second-layer ground plane, playing a role in fixing the structure. In this embodiment, the radiation patterns of the compact ultra-wideband directional spiral antenna in the xoz and yoz planes at 3.2 GHz are as shown in Figure 8 (a) and (b). The radiation patterns in the xoz and yoz planes at 4.5 GHz are as shown in Figure 9 (a) and (b). The radiation patterns in the xoz and yoz planes at 5.5 GHz are as shown in Figure 10 (a) and (b). It can be seen that the radiation pattern of the antenna shows a directional radiation mode, radiating along the Z-axis direction, and the back lobe of the radiation pattern is relatively small.

[0075] For the compact ultra-wideband directional spiral antenna designed by the present utility model, the designer can determine the number of turns of the spiral strip line of the radiation layer according to the required frequency band. Without increasing the height of the antenna, the overall circular polarization bandwidth is optimized through the "L"-shaped metal stub and the gaps around the reflector. The rotation direction of the circular polarization radiation of the compact ultra-wideband directional spiral antenna is the rotation direction of the spiral microstrip line of the radiation layer.

[0076] The specific embodiments described above further elaborate on the purpose, technical solution, and beneficial effects of the present utility model. It should be understood that the above description is only for the specific embodiments of the present utility model and is not used to limit the protection scope of the present utility model. In particular, it is pointed out that for those skilled in the art, any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A compact ultra-wideband directional spiral antenna, characterized in that, it includes: a first-layer radiation layer and a second-layer reflection metal structure; the first-layer radiation layer includes a first spiral microstrip line, a second spiral microstrip line, a tapered feeding microstrip line, a circular-ring microstrip structure, and a dielectric; the second-layer reflection metal structure is composed of two "L"-shaped metal branches and a metal plane; wherein, the first spiral microstrip line and the second spiral microstrip line form a spiral antenna that is correspondingly and staggeredly distributed on the upper and lower surfaces of the dielectric with the same spiral center as the reference; at the spiral center, the tapered feeding microstrip line is used as a feeding structure to perform impedance matching between the coaxial line and the spiral line; the second-layer reflection metal structure cooperates with the spiral antenna to achieve signal directional radiation; the ends of the two "L"-shaped metal branches are connected to the ends of the first spiral microstrip line and the second spiral microstrip line to achieve an ultra-wide circular polarization bandwidth.

2. The compact ultra-wideband directional spiral antenna according to claim 1, characterized in that, the two "L"-shaped metal branches are located at the two side edges of the metal plane and are integrally formed with the metal plane; the two "L"-shaped metal branches are symmetrically distributed along the spiral center point, are located on the same plane, and are higher than the metal plane.

3. The compact ultra-wideband directional spiral antenna according to claim 2, characterized in that, stepped openings are provided at the four vertex positions of the metal plane.

4. The compact ultra-wideband directional spiral antenna according to claim 3, characterized in that, four plastic posts are provided at the stepped opening positions for fixing the dielectric; the height of the plastic posts is 14 mm; the height of the plastic posts is the distance between the metal plane and the two "L"-shaped metal branches.

5. The compact ultra-wideband directional spiral antenna according to claim 4, characterized in that, the ends of the two spiral microstrip lines and the ends of the "L"-shaped metal branches are connected by metal posts; the circular-ring microstrip structure is arranged on the upper surface of the dielectric corresponding to the end of the second spiral microstrip line, so that the metal posts are tightly connected to the second spiral strip line; the tapered feeding microstrip line is fed by a GB405 coaxial line; the GB405 coaxial line passes through the reflection metal structure, and the outer conductor of the coaxial line is connected to the reflection metal structure using a metal flange; the grounding end of the GB405 coaxial line is welded to the second spiral microstrip line; the inner core of the GB405 coaxial line is welded to the tapered feeding microstrip line.

6. The compact ultra-wideband directional spiral antenna according to claim 5, characterized in that, the first spiral microstrip line and the second spiral microstrip line are respectively arranged on the upper and lower surfaces of the dielectric plate.

7. The compact ultra-wideband directional spiral antenna according to claim 6, characterized in that, the first spiral microstrip line and the second spiral microstrip line have 2 turns of spiral, a width of 4.5 mm, and a dielectric thickness of 1 mm.

8. The compact ultra-wideband directional spiral antenna according to claim 7, characterized in that, the inner diameter of the circular-ring microstrip structure is 2 mm and the outer diameter is 5 mm; The maximum width of the tapered feed microstrip line is 0.97 mm, the minimum width is 0.38 mm, and the number of turns is 1 turn.

9. A compact ultra-wideband directional spiral antenna according to claim 8, wherein, the thickness of the two "L"-shaped metal branches is 1 mm; the lengths of the two arms are 12.5 mm and 30 mm respectively.

10. A compact ultra-wideband directional spiral antenna according to claim 9, wherein, the metal plane is a square with a side length of 55 mm and a thickness of 1 mm; the widths of the stepped openings are 1.5 and 4.5 mm respectively, and the lengths are 6.5 mm and 4.5 mm respectively.

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