L-shaped probe feed microstrip antenna

Abstract

The application belongs to the technical field of communication and discloses an L-shaped probe feed microstrip antenna, which comprises, from top to bottom, a radiation patch, a first dielectric plate, a second dielectric plate and a metal ground plate fixedly arranged in sequence, wherein the second dielectric plate is vertically provided with a feed pin, the feed pin is located directly below the edge of the radiation patch, one end of the feed pin is connected with the metal ground plate, the other end of the feed pin is connected with one end of a coupling line horizontally arranged on the surface of the second dielectric plate, the other end of the coupling line points to the center of the second dielectric plate, and the coupling line is a curved coupling line, which is used for increasing the real part of the impedance of the antenna so as to match the characteristic impedance of the feed; a branch is further connected to the connecting point of the feed pin and the coupling line, the projection of the branch falls within the range of the metal ground plate, and the branch is used for adjusting the imaginary part of the impedance of the antenna so as to match the impedance of the external feed line.

Description

Technical Field

[0001] This invention belongs to the field of communication technology, and more specifically, relates to an L-shaped probe-fed microstrip antenna. Background Technology

[0002] Traditional L-shaped probe-fed microstrip antennas are often used as broadband antennas. The L-shaped probe consists of a vertical section and a top coupling line. The vertical section generates inductive reactance, while the coupling line generates capacitive reactance between the antenna and the patch. Together, they enable broadband resonance. Traditional L-shaped probe-fed antennas typically use air, foam, or other low-dielectric-constant materials as the dielectric layer. This results in a thicker antenna with a larger footprint, limiting its use on confined mounting platforms. When placed on a confined platform, a smaller antenna size is required. In this case, the L-shaped probe-fed antenna needs to use a high-dielectric-constant material as the dielectric layer. However, this results in a real impedance significantly less than 50 ohms, while the imaginary impedance is highly inductive. This impedance mismatch between the antenna and the external feed line leads to significant signal reflections, wasting energy and potentially interfering with the normal operation of the signal transmission system. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide an L-shaped probe-fed microstrip antenna that solves the problem that the imaginary part of the antenna impedance is highly inductive when the dielectric substrate is made of a high dielectric constant material, and that the real part of the antenna impedance does not match the characteristic impedance of the external feed line.

[0004] This invention provides an L-shaped probe-fed microstrip antenna, which, from top to bottom, comprises a radiating patch, a first dielectric substrate, a second dielectric substrate, and a metal ground plane fixed together, wherein:

[0005] A feed pin is vertically disposed within the second dielectric substrate. The feed pin is located directly below the edge of the radiating patch, with one end connected to an external feed line and the other end connected to one end of a coupling line horizontally disposed on the surface of the second dielectric substrate. The other end of the coupling line points towards the center of the second dielectric substrate, and the coupling line is a curved coupling line, used to increase the real part of the antenna impedance to match the feed characteristic impedance. A stub is also connected at the connection point between the feed pin and the coupling line. The projection of the stub falls within the range of the metal ground plane, and the stub is used to adjust the imaginary part of the antenna impedance to match the impedance of the external feed line.

[0006] Furthermore, the coupling line includes at least one bend; preferably, the bend is U-shaped and / or arc-shaped.

[0007] Furthermore, the branches are in the form of straight lines or patches parallel to the metal floor.

[0008] Furthermore, the branch includes at least two horizontally arranged branch units; preferably, during operation, the currents of the two branch units are equal in magnitude and opposite in direction.

[0009] Furthermore, both the first dielectric substrate and the second dielectric substrate are filled with a high dielectric constant material layer.

[0010] Furthermore, the two branch units are identical in shape and / or size.

[0011] Furthermore, the metal floor and the radiant patch are concentric circles, and the diameter of the radiant patch is smaller than the diameter of the metal floor.

[0012] Furthermore, a short-circuit post is vertically provided between the radiating patch and the metal floor, the short-circuit post being used to fix the radiating patch, the first dielectric plate, the second dielectric plate, and the metal floor together as a whole.

[0013] Furthermore, the short-circuit post is located at the center of the antenna.

[0014] Furthermore, the short-circuit posts are configured in multiple ways, and the multiple short-circuit posts are evenly arranged between the radiating patch and the metal floor with the geometric center of the radiating patch as the center.

[0015] Compared with the prior art, the above technical solutions conceived by this invention have the following main advantages:

[0016] 1. The antenna of this invention forms a curved, wound coupling line by bending a straight coupling line and connecting it to a feed pin. Compared to a straight coupling line of the same external dimensions, the actual length of the wound coupling line is longer, enabling the real part of the antenna impedance to match the feed characteristic impedance of the external feed line. When the antenna is working, the feed pin, located directly below the edge of the radiating patch, connects to the feed line. Current flows upward along the feed pin to the coupling line connected to it. The feed pin (vertical section) generates inductive reactance, and the coupling line (horizontal section), located directly below the radiating patch, generates capacitive reactance with the radiating patch. The coupling line does not directly contact the radiating patch but couples energy to the top radiating patch to form radiation.

[0017] 2. Because the coupling line of this invention adopts a curved form, one or more bends of the same or different shapes can be set as needed to extend the actual length of the coupling line, thereby increasing the real part of the antenna impedance and matching the feed characteristic impedance of the external feed line.

[0018] 3. In the antenna of this invention, the stubs are configured as at least two symmetrical stub units, and the two stub units have the same shape. During operation, the current flowing through the two stub units is equal in magnitude and opposite in direction, so they do not generate radiation externally and do not affect the antenna pattern. Furthermore, since the stubs can act as parallel capacitors, the inductive property of the original antenna impedance can be adjusted to near zero, ultimately achieving broadband impedance matching of the antenna. Attached Figure Description

[0019] Figure 1 This is a front view schematic diagram of an L-shaped probe-fed microstrip antenna structure according to an embodiment of the present invention;

[0020] Figure 2 This is a perspective view of an L-shaped probe-fed microstrip antenna structure according to an embodiment of the present invention;

[0021] Figure 3 This is a schematic diagram of an L-shaped probe-fed microstrip antenna structure provided in an embodiment of the present invention.

[0022] In the diagram: 1-Radiating patch, 2-Metal ground plane, 3-Dielectric layer, 4-Short circuit post, 5-Wound coupling line, 6-Stub, 7-Feeding pin. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0024] Example 1

[0025] like Figure 1-2 As shown, this embodiment discloses an L-shaped probe-fed microstrip antenna. From top to bottom, the antenna comprises a radiating patch 1, a first dielectric substrate (not shown), a second dielectric substrate (not shown), and a metal ground plane 2, all fixed together.

[0026] The radiation patch 1 is disposed on the upper surface of the first dielectric plate, and the metal floor 2 is disposed on the lower surface of the second dielectric plate;

[0027] A feed pin 7 is vertically disposed within the second dielectric substrate. The feed pin 7 is located directly below the edge of the radiating patch 1, with one end connected to the metal ground plane 2 and the other end connected to one end of a coupling line 5 horizontally disposed on the surface of the second dielectric substrate. The other end of the coupling line 5 points to the center of the second dielectric substrate. The coupling line 5 is a shorter curved coupling line formed by bending a longer straight coupling line, used to increase the real part of the antenna impedance to match the feed characteristic impedance. A stub 6 is also connected at the connection point between the feed pin 7 and the coupling line 5. The projection of the stub 6 falls within the range of the metal ground plane 2. The stub 6 is used to adjust the imaginary part of the antenna impedance to match the impedance of the external feed line.

[0028] In a preferred embodiment, the aforementioned bent and wound coupling line 5 includes at least one bend, which can be U-shaped, arc-shaped, a combination of U-shaped and arc-shaped, or any other tortuous and wound shape; the branch 6 is a straight line parallel to the metal ground plane 2 or other form of patch. Since both the first and second dielectric substrates use high dielectric constant materials, conventional L-shaped probe-fed antennas exhibit the disadvantage of low real impedance and inductive imaginary impedance, which cannot be effectively overcome by conventional means. The antenna of this invention overcomes the disadvantages of conventional L-shaped probe-fed antennas by bending a relatively long coupling line into a tortuous coupling line of a certain size.

[0029] In a preferred embodiment, the aforementioned stub 6 includes at least two horizontally and symmetrically arranged stub units; the two stub units are horizontally and symmetrically arranged, with an included angle of 180° between them. During operation, due to the symmetry of the stub units, the current on the two stub units is equal in magnitude and opposite in direction, so it does not generate radiation to the outside and does not affect the antenna pattern.

[0030] In a preferred embodiment, the aforementioned branch units are all straight branches, and the two branch units have the same shape or the same size, or both the shape and the size are the same, so as to ensure that the branch units can be arranged symmetrically.

[0031] In this preferred embodiment, the aforementioned metal floor 2 and radiant patch 1 are concentric circles or rectangles with their geometric centers coaxial, and the size of the radiant patch 1 is smaller than the size of the metal floor 2, so that radiant energy is emitted in the direction of the radiant patch.

[0032] In a preferred embodiment, the short-circuit post 4 is a hollow cylinder, located at the center of the antenna, serving both as a connection and fixing post and as a mounting hole for later installation of fixing screws.

[0033] In a preferred embodiment, multiple short-circuit posts 4 are provided, and the multiple short-circuit posts are evenly arranged between the radiant patch 1 and the metal floor 2.

[0034] Example 2

[0035] like Figure 3 As shown, this embodiment provides a broadband antenna operating in the BeiDou B3 band, with a center frequency of approximately 1.24 GHz and a relative operating bandwidth of approximately 10%. The half-wavelength of this band is approximately 120 mm. If a low dielectric constant material is used to make the antenna, the antenna diameter is approximately 120 mm. If a high dielectric constant material is used, such as Taconic RF60 material with a relative dielectric constant of 6.15, the antenna size will be reduced accordingly. In this embodiment, the high dielectric constant material Taconic RF60 is used as the dielectric layer 3 composed of at least two dielectric substrates.

[0036] Specifically, the antenna includes a top radiating patch 1 disposed on the upper surface of the dielectric layer 3, the dielectric layer 3, a metal ground plane 2 disposed at the bottom of the dielectric layer 3, a shorting post 4, a coupling line 5, a stub 6, and a feed pin 7. The radiating patch 1 and the metal ground plane 2 are both circular, but their diameters differ, with the diameter of the radiating patch 1 being slightly smaller than that of the metal ground plane 2. The shorting post 4 and the feed pin 7 are vertically disposed between the radiating patch 1 and the metal ground plane 2. Specifically, the shorting post 4 is located at the center of the radiating patch 1 and the metal ground plane 2, and is used to fix the dielectric layer 3, which is located inside the antenna dielectric substrate. The feed pin 7 is located directly below the edge of the radiating patch 1, with one end connected to the core wire of the external feed line and the other end connected to a horizontally positioned bent coupling line 5. The coupling line 5 is formed by bending and winding a long straight coupling line to increase the real part of the antenna impedance, thereby matching it with the feed characteristic impedance. After the coupling line 5 and the feed pin 7 are connected, they form an L-shaped feed unit. A stub 6 is also connected at the connection point between the feed pin 7 and the bent coupling line 5. The projection of the stub 6 falls completely within the range of the metal ground plate 2. From the feed pin, the stub 6 is equivalent to a parallel capacitor. The introduction of this parallel capacitor can adjust the imaginary part of the antenna to close to 0, ultimately achieving antenna impedance matching with the feed line and ensuring the wideband matching performance of the antenna.

[0037] The aforementioned coupling line 5 is as follows Figure 2 Like the coupling line 5 shown, it also has a curved shape with multiple rectangular bends. The longer the coupling line is, the more bends can be set so that it can match the antenna size and increase the real part of the antenna impedance. The branch 6 is a straight line parallel to the metal ground 2 and perpendicular to the feed pin 7. The antenna of the present invention overcomes the disadvantages of low real part of antenna impedance and inductive imaginary part by using a curved coupling line with adjustable length.

[0038] Stub 6 includes two pairs of horizontally and symmetrically arranged stub units. The two pairs of stub units are identical in shape and size, and are symmetrically arranged. The included angle between the two symmetrical stub units is 180°, ensuring that the current flowing through the stub units is of the same magnitude but opposite in direction during operation. This allows the imaginary part of the antenna impedance to be adjusted to near zero, ultimately achieving antenna impedance matching with the feed line and ensuring broadband matching performance. In other embodiments, stub 6 may also include more pairs of symmetrically arranged stub units.

[0039] Compared to the conventional straight coupling line, the curved coupling line 5 in this embodiment can adjust the actual length of the coupling line by changing the length of the curved section without changing the feed point position. This allows the antenna to overcome the problem of low real part of antenna impedance caused by using a high dielectric constant material as the dielectric layer.

[0040] In this embodiment, when the antenna is operating, the bottom of the feed pin 7 is connected to the core wire of the external feed line. Normally, the external feed line passes through a hole in the metal floor and connects to the feed pin 7. Current flows upward along the feed pin 7 to the curved coupling line 5. The feed pin 7 (vertical section) generates inductive reactance, and the curved coupling line 5 generates capacitive reactance between itself and the top radiating patch. The curved coupling line 5 couples energy to the top radiating patch 1, forming radiation. Because the coupling line 5 is curved, its actual length is extended, increasing the real part of the antenna impedance to match the feed characteristic impedance. Simultaneously, the loaded stub 6 acts as a parallel capacitor, adjusting the inductive aspect of the original antenna impedance to near zero, ultimately achieving broadband impedance matching. Furthermore, due to the symmetry of the stub 6, the currents on the two stub units are equal in magnitude but opposite in direction, producing no external radiation and not affecting the antenna pattern.

[0041] In multilayer microstrip antennas, multiple short-circuit pillars can be used, which are evenly arranged at and around the geometric center of the antenna. In such antennas, multiple hollow short-circuit pillars can serve as the outer conductors of the coaxial feed lines when the upper antenna layers pass through the lower antenna layers.

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An L-shaped probe-fed microstrip antenna, characterized in that, The antenna comprises, from top to bottom, a radiating patch (1) fixed together, a first dielectric substrate, a second dielectric substrate, and a metal ground plane (2), wherein: A feed pin (7) is vertically arranged inside the second dielectric substrate. The feed pin (7) is located directly below the edge of the radiating patch (1), and one end is connected to the external feed line. The other end is connected to one end of the coupling line (5) horizontally arranged on the second dielectric substrate. The other end of the coupling line (5) points to the center of the second dielectric substrate. The coupling line (5) is a curved coupling line to extend the actual length of the coupling line (5) so as to increase the real part of the antenna impedance and match it with the feed characteristic impedance. A stub (6) is also connected to the connection point between the feed pin (7) and the coupling line (5). The projection of the stub (6) falls within the range of the metal ground plane (2). The stub (6) is used to adjust the imaginary part of the antenna impedance so as to match it with the impedance of the external feed line. The stub (6) includes at least two stub units that are parallel and symmetrically arranged with respect to the metal ground plane (2). Both the first dielectric substrate and the second dielectric substrate are filled with a high dielectric constant material layer.

2. The L-shaped probe-fed microstrip antenna as described in claim 1, characterized in that, The coupling line (5) includes at least one bend.

3. The L-shaped probe-fed microstrip antenna as described in claim 2, characterized in that, The bend is U-shaped and / or arc-shaped.

4. The L-shaped probe-fed microstrip antenna as described in claim 1, characterized in that, The branch (6) is a straight line or patch parallel to the metal floor (2).

5. The L-shaped probe-fed microstrip antenna as described in claim 1, characterized in that, When the L-shaped probe-fed microstrip antenna is in operation, the currents of the two stub units are equal in magnitude and opposite in direction.

6. The L-shaped probe-fed microstrip antenna as described in claim 1, characterized in that, The two branch units are identical in shape and / or size.

7. The L-shaped probe-fed microstrip antenna as described in claim 1, characterized in that, The metal floor (2) and the radiation patch (1) are concentric circles, and the diameter of the radiation patch (1) is smaller than the diameter of the metal floor (2).

8. The L-shaped probe-fed microstrip antenna as described in claim 1, characterized in that, A short-circuit post (4) is vertically arranged between the radiation patch (1) and the metal floor (2). The short-circuit post (4) is used to fix the radiation patch (1), the first dielectric plate, the second dielectric plate and the metal floor (2) together.

9. An L-shaped probe-fed microstrip antenna as described in claim 8, characterized in that, The short-circuit post (4) is located at the center of the antenna.

10. An L-shaped probe-fed microstrip antenna as described in claim 8, characterized in that, The short-circuit post (4) is configured as a plurality of such posts, and the plurality of short-circuit posts are evenly arranged between the radiating patch (1) and the metal floor (2) with the geometric center of the radiating patch as the center.

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