A microstrip antenna structure with widened beam

Abstract

The present invention discloses a beam-broadening microstrip antenna structure, comprising a base, a metal cover, and an antenna body. The base is mounted with the metal cover, which is a hollow structure. The top of the metal cover defines a first radiation port, and the periphery of the metal cover defines a second radiation port. The antenna body is fixedly mounted between the metal cover and the base. The present invention effectively broadens the beam width of a microstrip antenna and is applicable not only to linearly polarized microstrip antennas but also to circularly polarized microstrip antennas, offering improved adaptability.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless communications, and in particular to a microstrip antenna structure with a broadened beam. Background Art

[0002] In tactical wireless communication applications, long-distance, wide-area communication coverage is achieved through satellites, aerial base stations, and radio relays. To quickly and maximize the number of aerial node signals, especially when there are only a few aerial nodes and the signals are weak, ground communication terminal antennas must possess wide-beam performance, meaning high gain at low elevation angles. Currently, the most widely used wide-beam antennas include helical antennas, microstrip antennas, and printed dipole antennas. Helical antennas offer wide-beam capability, but their profile is relatively high, typically around 0.75λ. Microstrip antennas have a low profile, but their half-power beamwidth (HWBW) is narrow, typically around 70°. Printed dipole antennas offer both wide-beam and low-profile performance, but their wide-beam capability is primarily in the H-plane, with an E-plane HWBW of approximately 70°. Therefore, improving antenna wide-beam performance has long been a challenge for antenna researchers.

[0003] In the existing technology, He Haidan proposed a microstrip dielectric antenna in "A New Wide-Beam Circularly Polarized Antenna—Microstrip Dielectric Antenna," which can achieve a beamwidth greater than 180° and a gain greater than 0.5dB at elevation angles above 10°. However, the dielectric plate used in this design uses a high-permittivity dielectric substrate, and the substrate's side length is approximately five times that of the microstrip patch antenna. This makes it both costly and excessively large for practical applications.

[0004] The above-mentioned prior art still has certain defects in widening the beam width of the microstrip antenna. Currently, no effective solution has been proposed for simply and effectively widening the beam width of the microstrip antenna. Summary of the Invention

[0005] In view of this, it is necessary to provide a microstrip antenna structure with a widened beam to solve the technical problem of how to improve the wide beam performance of the antenna in the prior art.

[0006] In order to achieve the above technical objectives, the technical solution of the present invention provides a microstrip antenna structure with a widened beam, including: a base, a metal cover and an antenna body; the metal cover is installed on the base, the metal cover is a hollow structure, and a first radiation port is opened on the top of the metal cover, and the antenna body is fixed between the metal cover and the base.

[0007] Furthermore, the metal cover is a metal frustum.

[0008] Furthermore, second radiation openings are provided around the metal cover.

[0009] Furthermore, the second radiation ports are symmetrically distributed on the inclined surfaces around the metal frustum.

[0010] Furthermore, the metal frustum is a circular frustum or a square frustum.

[0011] Furthermore, when the metal frustum adopts the circular frustum, the first radiation port is a circular port; when the metal frustum adopts the square frustum, the first radiation port is a square port; and the second radiation port is a square port or a circular port.

[0012] Furthermore, the length of the second radiation port does not exceed 0.5λ, where λ is the wavelength of the center frequency of the antenna.

[0013] Furthermore, the antenna body is a circularly polarized antenna or a linearly polarized antenna.

[0014] Furthermore, the antenna body includes a metal base plate, a lower dielectric plate, a metal coupling patch, an upper dielectric plate and a metal radiation patch, and the metal base plate, the lower dielectric plate, the metal coupling patch, the upper dielectric plate and the metal radiation patch are stacked in sequence from bottom to top.

[0015] Furthermore, the metal cover is installed in cooperation with the base, the base is provided with a receiving cavity, and the antenna body is embedded in the receiving cavity.

[0016] Compared with the prior art, the beneficial effects of the present invention include: the metal cover is a hollow structure, a first radiation port is provided on the top of the metal cover, a second radiation port is provided around the metal cover, and the antenna body is fixed between the metal cover and the base; through the above-mentioned setting method, the beam width of the microstrip antenna can be simply and effectively widened. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 2 is a schematic diagram of a microstrip antenna structure without a metal cover according to an embodiment of the present invention;

[0018] Figure 2 is a schematic diagram of a microstrip antenna structure equipped with a metal cover according to an embodiment of the present invention;

[0019] Figure 3 is a main radiation pattern of the microstrip antenna structure according to an embodiment of the present invention at Phi=0°;

[0020] Figure 4 The main radiation pattern of the microstrip antenna structure according to an embodiment of the present invention at Phi=90°;

[0021] Figure 5 1 is a return loss S11-frequency comparison curve when Phi=0° and Theta=0° according to an embodiment of the present invention;

[0022] Figure 6 1 is an axial ratio-frequency comparison curve according to an embodiment of the present invention when Phi=0° and Theta=0°;

[0023] In the figure: 1. base, 2. antenna body, 3. metal cover, 31. first radiation port, 32. second radiation port. DETAILED DESCRIPTION

[0024] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, and are not used to limit the scope of the present invention.

[0025] The existing microstrip antenna consists of a metal base plate, a lower dielectric plate, a metal coupling patch, an upper dielectric plate and a metal radiation patch. This antenna is a double-layer dual-fed circularly polarized microstrip antenna. By introducing an air layer and dual feeding points, it achieves broadband circular polarization. However, its beam width is not wide enough (generally 60° to 80°), which limits the use scenarios of this circularly polarized microstrip antenna.

[0026] To do this, see Figure 2 The present invention provides a microstrip antenna structure with a broadened beam, comprising: a base 1, an antenna body 2 and a metal cover 3.

[0027] The antenna body 2 is fixed in the middle of the upper end surface of the base 1 . The base 1 can be circular or square. It should be understood that this embodiment does not limit the specific structure of the base 1 .

[0028] The antenna body 2 includes a metal base plate, a lower dielectric plate, a metal coupling patch, an upper dielectric plate and a metal radiation patch, and the metal base plate, the lower dielectric plate, the metal coupling patch, the upper dielectric plate and the metal radiation patch are stacked in sequence from bottom to top.

[0029] The metal cover 3 has a hollow cavity with a symmetrical structure inside. A first radiation port 31 is opened on the top of the metal cover 3, and second radiation ports 32 are evenly opened around the metal cover 3. The first radiation port 31 and the second radiation port 32 are connected to the hollow cavity. It should be noted that the sizes of the first radiation port 31 and the second radiation port 32 are quantified according to different frequency bands and actual antenna performance requirements. The wall thickness of the metal cover 3 has little effect on the wide beam performance of the antenna.

[0030] In one embodiment, based on antenna aperture field theory, the relationship between antenna aperture area and beam range is as follows:

[0031] λ 2 =A e Ω A (Formula 1)

[0032] Among them, the antenna wavelength λ is constant; A e is the aperture area of the antenna, Ω A is the antenna's beam solid angle.

[0033] Ω A ≈θ 0.5E θ 0.5H (Formula 2)

[0034] Among them, θ 0. is the half-power beamwidth of the main lobe of the antenna pattern E plane, θ 0. is the half-power beamwidth of the main lobe of the antenna pattern H plane.

[0035] It can be seen that by compressing the aperture area of the first radiation port 31, a wider beam radiation performance can be obtained; at the same time, in order to further expand the beam width of the microstrip antenna, according to the theory of the waveguide slot antenna, a second radiation port 32 is opened around the metal cover 3, and the opened second radiation port 32 cuts off the current line on the surface of the inner wall of the metal cover 3. Part of the surface current bypasses the second radiation port 32, and the other part flows through the second radiation port 32 in the original direction in the form of displacement current, so that the second radiation port 32 is excited to radiate electromagnetic waves into the outer space.

[0036] Optionally, the metal cover 3 is a metal frustum, and the metal frustum is a circular frustum or a square frustum; the second radiation openings 32 are symmetrically arranged on the inclined surfaces around the metal frustum, and preferably the second radiation openings 32 are rectangular openings, and there are four of them.

[0037] In one embodiment, to obtain stronger radiation, the second radiation openings 32 should vertically intercept the current line at the location with the maximum current density, that is, the second radiation openings 32 should be symmetrically distributed on the four inclined surfaces of the metal frustum to obtain better beam broadening effect.

[0038] It should be noted that the antenna body 2 of the present invention is not only applicable to linearly polarized microstrip antennas, but also to circularly polarized microstrip antennas. Preferably, the antenna body 2 is a circularly polarized microstrip antenna.

[0039] The relationship between the height of the metal cover 3, the aperture of the first radiation port 31, the size of the second radiation port 32 and the beam width performance is as follows:

[0040] When the aperture of the first radiation port 31 and the size of the second radiation port 32 remain unchanged, the half-power beam width of the antenna increases as the height of the metal cover 3 decreases, but when its height is reduced to around 0.05λ, the axial ratio of the circularly polarized microstrip antenna will seriously deteriorate and the antenna beam width will also begin to decrease. As the height of the metal cover 3 increases, the antenna axial ratio gradually improves. When its height increases to around 0.1λ, the antenna axial ratio and beam width reach a good balance.

[0041] When the height of the metal cover 3 and the diameter of the first radiation port 31 remain unchanged, the antenna's half-power beamwidth increases with the size of the second radiation port 32. This is because the larger second radiation port 32 increases the range over which it intercepts current lines on the inner surface of the metal cover 3, enhancing the radiation from the second radiation port 32. In particular, within the half-wavelength range, the longer the second radiation port 32, the more pronounced the antenna beam broadens. Therefore, by adjusting the size of the second radiation port 32, a wider antenna half-power beamwidth can be achieved.

[0042] Taking the metal cover 3 as a square frustum as an example, a specific embodiment of the present invention is given below in combination with specific numerical values:

[0043] In Example 1, the aperture of the first radiation port remains unchanged, and the length and width of the four second radiation ports are both 20mm×8.5mm. When the height of the metal cover h=3.3mm, the beam widths of the circularly polarized microstrip antenna at the center frequency points Phi=0° and Phi=90° are 128° and 149° respectively, and the axial ratio AR in the working frequency band is mostly above 3dB; when the height of the antenna cover is increased to 5mm (about 0.08λ), the beam widths of the circularly polarized microstrip antenna at the center frequency points Phi=0° and Phi=90° are 131° and 146° respectively, and the axial ratio AR in the working frequency band is <3dB.

[0044] In Example 2, the height h of the metal cover is constant, the width W of the second radiation port is 8.5 mm, and when the length L of the second radiation port is 19 mm, the beam widths of the circularly polarized microstrip antenna at the center frequency points Phi=0° and Phi=90° are 114° and 122° respectively. When the length L of the second radiation port is 23 mm, the beam widths of the circularly polarized microstrip antenna at the center frequency points Phi=0° and Phi=90° are 136° and 163° respectively.

[0045] In Example 3, the height h of the metal cover is constant, the length L of the second radiation port is 20 mm, when the width W of the second radiation port is 7.5 mm, the beam widths of the circularly polarized microstrip antenna at the center frequency points Phi=0° and Phi=90° are 118° and 129° respectively; when the width W of the second radiation port is 10.5 mm, the beam widths of the circularly polarized microstrip antenna at the center frequency points Phi=0° and Phi=90° are 126° and 139° respectively.

[0046] Example 4, the metal cover is 5mm high, the side length of the first radiation port is 25mm, and the size of the second radiation port is 20mm×8.5mm; the antenna body is embedded in the accommodating cavity of the metal base, the length and width of the accommodating cavity of the base are 45mm×45mm, and its height is 5mm; the antenna body operates in the frequency band of 4.4~5.0GHz, and the center operating frequency is 4.7GHz; the antenna body is a dual-fed double-layer circularly polarized microstrip antenna, and includes a metal base plate, a lower dielectric plate, a circular metal coupling patch, an upper dielectric plate and a circular shaped metal radiation patch, wherein a lower dielectric plate is provided above the metal base plate, and the length and width of the metal base plate are 45mm×45mm; the thickness of the lower dielectric plate is 0.635mm, and a Wilkinson feed network and a circular metal coupling patch are provided above the lower dielectric plate, and the radius of the circular metal coupling patch is 7.4mm; an upper dielectric plate is provided above the circular metal coupling patch, and the thickness of the upper dielectric plate is 0.508mm. A circular metal radiation patch is etched on the upper surface of the upper dielectric plate, and the radius of the circular metal radiation patch is 13.5mm.

[0047] Figure 1 It is a microstrip antenna structure without a metal cover; Figure 2 It is a microstrip antenna structure with a metal cover installed; Figure 3 and Figure 4 They are Figure 1 and Figure 2 The radiation direction of the microstrip antenna structure is shown in Table 1. The dotted line in the figure is the radiation direction of the microstrip antenna structure without a metal cover, and the solid line is the radiation direction of the microstrip antenna structure with a metal cover. The radiation performance parameters are shown in Table 1 and Table 2 respectively.

[0048] Table 1: Radiation performance parameters of microstrip antenna structure without metal cover

[0049]

[0050] Table 2: Radiation performance parameters of microstrip antenna structure with metal cover

[0051]

[0052] From the comparison of Table 1 and Table 2, it can be seen that the half-power beamwidth of the microstrip antenna structure installed with a metal cover at the Phi = 0° plane and the Phi = 90° plane is much larger than that of the microstrip antenna structure without a metal cover, that is, the present invention can effectively widen the beamwidth of the microstrip antenna.

[0053] In summary, the present invention can flexibly adjust the half-power beamwidth of the antenna by adjusting the relevant parameters of the metal cover; due to the symmetry of the metal cover, the present invention is not only applicable to linearly polarized microstrip antennas, but also to circularly polarized microstrip antennas, and has better adaptability.

[0054] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A microstrip antenna structure with a broadened beam, characterized in that: include: A base, a metal cover and an antenna body; the metal cover is mounted on the base, the metal cover is a hollow structure, a first radiation port is provided on the top of the metal cover, the antenna body is fixed between the metal cover and the base, second radiation ports are provided around the metal cover, the metal cover is a metal frustum, and the second radiation ports are symmetrically distributed on the inclined surfaces around the metal frustum; when the aperture of the first radiation port and the size of the second radiation port remain unchanged, the half-power beamwidth of the antenna increases as the height of the metal cover decreases, but when its height is reduced to approximately 0.05λ, the axial ratio of the circularly polarized microstrip antenna deteriorates and the antenna beamwidth also begins to decrease. As the height of the metal cover increases, the antenna axial ratio gradually improves. When its height increases to approximately 0.1λ, the antenna axial ratio and beamwidth reach a balance; when the height of the metal cover and the aperture of the first radiation port remain unchanged, the half-power beamwidth of the antenna increases as the size of the second radiation port increases, and λ is the wavelength of the antenna center frequency.

2. The beam-broadening microstrip antenna structure according to claim 1, characterized in that: The metal frustum is a circular frustum or a square frustum.

3. The beam-broadening microstrip antenna structure according to claim 2, wherein: When the metal frustum adopts the circular frustum, the first radiation port is a circular port; when the metal frustum adopts the square frustum, the first radiation port is a square port; the second radiation port is a square port or a circular port.

4. The beam-broadening microstrip antenna structure according to claim 3, characterized in that: The length of the second radiation port does not exceed 0.5λ.

5. The beam-broadening microstrip antenna structure according to claim 1, wherein: The antenna body is a circularly polarized antenna or a linearly polarized antenna.

6. The beam-broadening microstrip antenna structure according to claim 1, characterized in that: The antenna body includes a metal base plate, a lower dielectric plate, a metal coupling patch, an upper dielectric plate and a metal radiation patch, wherein the metal base plate, the lower dielectric plate, the metal coupling patch, the upper dielectric plate and the metal radiation patch are stacked in sequence from bottom to top.

7. The beam-broadening microstrip antenna structure according to claim 1, characterized in that: The metal cover is installed in cooperation with the base. The base is provided with a receiving cavity, and the antenna body is embedded in the receiving cavity.

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