Microstrip patch antenna based on antipodal double spiral grooves

Abstract

The invention relates to a microstrip patch antenna based on an antipodal double-helix groove, which comprises the antipodal double-helix groove, a patch, a substrate, a grounding plate and a coaxial probe, and is characterized in that the substrate is mounted on the grounding plate, the patch is mounted on the substrate, the antipodal double-helix groove is formed in the patch, and the coaxial probe sequentially penetrates through the grounding plate, the substrate and the patch; the coaxial probe is used for feeding the patch, and a radio frequency electromagnetic field is generated between the patch and the grounding plate. According to the microstrip patch antenna, the antipodal double-spiral grooves are formed, the path length of current flowing through the patch is increased, the resonant frequency of the antenna is reduced to a large extent, meanwhile, the good radiation characteristic is kept, the antenna radiation efficiency is high, the directional diagram is regular, and the electrical size of the microstrip patch antenna is reduced while the high radiation efficiency is kept.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of patch antennas, and particularly relates to a microstrip patch antenna based on a pair of double helical grooves. BACKGROUND

[0002] Microstrip antennas are widely used in mobile communication technology, modern medicine, space technology and military technology, etc. because the size of the antennas is required to be small in these fields. For example, in the field of mobile communication, small and portable devices make the application more convenient; in the field of modern medicine, small microstrip antennas can be integrated into in-vivo medical devices, such as implantable cardiac pacemakers, and small antennas can reduce the invasion to the patient's body and provide a more comfortable experience.

[0003] Although microstrip antennas have many advantages in structure and physical properties, such as low profile and light weight, the size of traditional patch antennas is usually half-wavelength, which limits their application in small devices and has certain limitations.

[0004] At present, a common method for reducing the size of microstrip antennas is to use a metal short-circuit column or a short-circuit wall, but this method often leads to a decrease in antenna efficiency and may cause distortion of the directional diagram, so it also has its limitations.

[0005] How to further reduce the size of traditional microstrip patch antennas while ensuring high radiation efficiency is an important challenge in the field at present.

[0006] The utility model patent with the publication number CN203398280U discloses a symmetrical spiral double-frequency microstrip antenna. It comprises a substrate, a rectangular radiation patch, a left spiral radiation patch, a right spiral radiation patch, an impedance matching input transmission line and a rectangular metal ground plate. The upper surface of the substrate is provided with the rectangular radiation patch, the left spiral radiation patch, the right spiral radiation patch and the impedance matching input transmission line. The lower surface of the substrate is provided with the rectangular metal ground plate. The left end of the rectangular radiation patch is connected with the left spiral radiation patch, the right end of the rectangular radiation patch is connected with the right spiral radiation patch, one end of the impedance matching input transmission line is connected with the rectangular radiation patch, the other end of the impedance matching input transmission line is connected with the bottom end of the substrate, and the bottom end of the rectangular metal ground plate is connected with the bottom end of the substrate. The electrical size of the patent can be further reduced.

[0007] Therefore, how to further reduce the size of the patch while ensuring high radiation efficiency is an urgent problem to be solved at present. SUMMARY

[0008] The present application is to overcome the defects of the prior art and provides a microstrip patch antenna based on a pair of double helical grooves.

[0009] The object of the present application can be realized by the following technical solutions. According to one aspect of the present application, a microstrip patch antenna based on a pair of double helical slots is provided, comprising a pair of double helical slots, a patch, a substrate, a ground plate and a coaxial probe, the substrate is installed on the ground plate, the patch is installed on the substrate, the pair of double helical slots is arranged on the patch, and the coaxial probe sequentially passes through the ground plate, the substrate and the patch; the coaxial probe is used for feeding the patch, and a radio frequency electromagnetic field is generated between the patch and the ground plate.

[0010] As a preferred technical solution, the pair of double helical slots comprises two helical sub-slots distributed in a pair of feet.

[0011] As a preferred technical solution, the two helical sub-slots are both Archimedes spirals.

[0012] As a preferred technical solution, the helical sub-slots each comprise an inner helix and an outer helix.

[0013] As a preferred technical solution, the helical growth rate of the inner helix and the outer helix is less than a first preset value, and the distance between the starting point of the helix of the outer helix and its origin is less than half the width of the patch.

[0014] As a preferred technical solution, the coaxial probe comprises a coaxial probe outer conductor and a coaxial probe inner conductor, the coaxial probe outer conductor is installed on the ground plate, and the coaxial probe inner conductor is installed in the coaxial probe outer conductor and sequentially passes through the substrate and the patch.

[0015] As a preferred technical solution, the ground plate is provided with a circular groove, and the coaxial probe outer conductor is installed on the circular groove.

[0016] As a preferred technical solution, the coaxial probe inner conductor and the coaxial probe outer conductor are coaxial.

[0017] As a preferred technical solution, the characteristic impedance of the coaxial probe is a second preset value.

[0018] As a preferred technical solution, the substrate is a substrate made of a low dielectric constant material.

[0019] Compared with the prior art, the present application has the following beneficial effects: 1. The present application sets a pair of double helical slots, increases the path length of the current flowing through the patch, so that the antenna resonance frequency is greatly reduced, while maintaining good radiation characteristics, the antenna radiation efficiency is high, the directional diagram is regular, while maintaining high radiation efficiency, the electrical size of the microstrip patch antenna is reduced.

[0020] 2. The application sets a coaxial probe for feeding the patch, so that the patch and the ground plate generate a radio frequency electromagnetic field.

[0021] 3. The helical sub-slot of the application adopts an Archimedes spiral, and the uniform structure of the Archimedes spiral can ensure stable transmission of signals or energy.

[0022] 4. The application can change the parameters of the helical sub-slot, optimize the design of the helical slot, change the current path in the patch, and thus realize the regulation of the resonant frequency of the antenna. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a top view of the antenna structure of the application; Figure 2 is a side view of the antenna structure of the application; Figure 3 is a structure diagram of the double helical sub-slot of the application; Figure 4 is a structure diagram of the helical sub-slot of the application; Figure 5 is a coordinate system diagram of the inner helical line of the application; Figure 6 is a coordinate system diagram of the outer helical line of the application; Figure 7 is a comparison diagram of the reflection coefficient curves of the microstrip patch antenna provided by the embodiment of the application and the conventional microstrip patch antenna at the same resonant frequency; Figure 8 is a gain curve diagram of the microstrip patch antenna provided by the embodiment of the application; Figure 9 is an efficiency curve diagram of the microstrip patch antenna provided by the embodiment of the application; Figure 10 is an E-plane radiation pattern diagram of the microstrip patch antenna provided by the embodiment of the application; Figure 11 is an H-plane radiation pattern diagram of the microstrip patch antenna provided by the embodiment of the application; Legend 1. Double helical sub-slot, 101. Outer helical line, 102. Inner helical line, 2. Patch, 3. Substrate, 4. Ground plate, 5. Coaxial probe, 501. Outer conductor of coaxial probe, 502. Inner conductor of coaxial probe, W. Width of patch, L. Length of patch, h. Thickness of substrate, d. Distance between outer helical line and inner helical line. DETAILED DESCRIPTION

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0025] Electrical size is defined as the ratio of physical size to operating wavelength. Since antennas involve electromagnetic waves and have an operating wavelength, electrical size is more significant than physical size. A reduction in electrical size means that for the same physical size, a longer operating wavelength results in a shorter electrical size; or, for the same operating wavelength, a smaller physical size results in a shorter electrical size. Both of these cases can be considered as a reduction in electrical size.

[0026] The purpose of this invention is to design a miniaturized microstrip patch antenna with an antipodal double helical groove structure, which reduces its electrical size while maintaining high radiation efficiency.

[0027] Example 1 like Figures 1-4 As shown, a microstrip patch antenna based on an antipodal double helix groove includes an antipodal double helix groove 1, a patch 2, a substrate 3, a ground plane 4, and a coaxial probe 5. The substrate 3 is mounted on the ground plane 4, the patch 2 is mounted on the substrate 3, the antipodal double helix groove 1 is disposed on the patch 2, and the coaxial probe 5 passes through the ground plane 4, the substrate 3, and the patch 2 in sequence. The coaxial probe 5 is used to power the patch 2, and a radio frequency electromagnetic field is generated between the patch 2 and the ground plane 4.

[0028] In this embodiment, the components include an antipodal double helix groove 1, a patch 2, a substrate 3, a ground plane 4, and a coaxial probe 5. The patch 2 is rectangular. The ground plane 4 serves as the bottom layer. The patch 2 and the substrate 3 are stacked sequentially on the ground plane 4 from top to bottom. The patch 2 has an antipodal double helix groove 1. The ground plane 4 is connected to the patch 2 via the coaxial probe 5. The coaxial probe 5, the ground plane 4, and the patch 2 form a signal transmission loop. The coaxial probe 5 feeds power to the patch 2, generating a radio frequency electromagnetic field between the rectangular patch 2 with the antipodal double helix groove 1 and the ground plane 4.

[0029] The antipodal double helix groove 1 includes two antipodal distributed helical sub-grooves. Both helical sub-grooves are Archimedean spirals. Each helical sub-groove includes an inner helix 102 and an outer helix 101. The helical growth rate of the inner helix 102 and the outer helix 101 is less than a first preset value, and the distance between the starting point of the outer helix 101 and its origin is less than half the width of the patch 2.

[0030] In this embodiment, the antipodal double spiral groove 1 further includes two straight grooves. The two spiral sub-grooves are respectively connected to the straight grooves, and the two straight grooves are parallel to each other. The two spiral sub-grooves are antipodally distributed (centrally symmetric), that is, one groove is obtained by rotating the other groove by 180°. The spiral sub-groove is formed by an inner spiral line and an outer spiral line. The spiral sub-groove is connected to the straight groove and extends from the starting point of the spiral sub-groove to the edge of the patch 2.

[0031] As Figure 5 and Figure 6 shown, the spiral of the antipodal double spiral groove 1 is an Archimedean spiral. Since one of the spiral sub-grooves is obtained by rotating the other spiral sub-groove by 180°, only any one of the spiral sub-grooves needs to be determined. Each spiral sub-groove consists of two spiral lines, which are divided into an inner spiral line 102 and an outer spiral line 101. The coordinate equation of the inner spiral line 102 is: The coordinate equation of the outer spiral line 101 is: where r0 is the distance between the starting point of the inner spiral line and the origin, r1 is the distance between the starting point of the outer spiral line and the origin, a is the spiral growth rate, φ is the angle of spiral rotation, and its value range is [0, 1.5π], where π is the mathematical constant pi. d is the width of the groove. Since the width of the groove remains constant, d is equal to the initial width of the groove r1 - r0.

[0032] To ensure that the spiral groove can play a role, it is required that the spiral growth rate a < 0.002 and r1 < W / 2; the parameters of the loaded spiral groove are respectively: r0 = 0.1 mm, r1 = 0.2 mm, that is, d = 0.1 mm, a = 0.0006. The overall size of the patch 2 is L = 20 mm, W = 20 mm; the thickness of the patch 2 is 0.035 mm. <于

[0033] The spiral groove can be optimized by changing the parameters of the inner spiral and the outer spiral, such as the parameters r0, r1, d, a, etc., to change the current path in the patch, so as to realize the regulation of the resonant frequency of the antenna.

[0034] The coaxial probe 5 includes a coaxial probe outer conductor 501 and a coaxial probe inner conductor 502. The coaxial probe outer conductor 501 is installed on the ground plane 4, and the coaxial probe inner conductor 502 is installed in the coaxial probe outer conductor 501 and sequentially passes through the substrate 3 and the patch 2.

[0035] The ground plane 4 is provided with a circular groove, and the coaxial probe outer conductor 501 is installed on the circular groove. The coaxial probe inner conductor 502 and the coaxial probe outer conductor 501 are coaxial. The characteristic impedance of the coaxial probe 5 is a second preset value.

[0036] In this embodiment, the transverse dimension of the grounding plate 4 (i.e., the same as the direction of W) is 60 mm, and the thickness t is 0.035 mm. The grounding plate 4 and the rectangular patch 2 of the antipodal double helix groove 1 are made of any metal selected from silver, copper, and aluminum.

[0037] In this embodiment, the characteristic impedance of the coaxial probe 5 is 50 ohms; the ground plane 4 has a circular groove at the location of the coaxial probe 5 for mounting the outer conductor 501 of the coaxial probe, and the inner conductor 502 of the coaxial probe passes through the circular groove and is connected to the patch 2 through the substrate 3, and the inner conductor 502 of the coaxial probe does not contact the circular groove. The inner conductor 502 of the coaxial probe is used to feed power to the patch 2.

[0038] The substrate 3 is made of a low dielectric constant material.

[0039] In this embodiment, substrate 3 is a dielectric substrate. To meet the miniaturization requirements of microstrip antennas, high dielectric constant dielectric substrates are typically used. However, high dielectric constant substrates are difficult to process and have high costs. Therefore, the substrate 3 in this embodiment is made of F4B (a high-frequency composite material with polytetrafluoroethylene (PTFE) as the substrate), with a relative dielectric constant εr=2.2, a loss tangent of tanδ=0.001, a lateral dimension G of 60mm, and a thickness h of 12mm. This invention uses a low dielectric constant dielectric substrate to fabricate a microstrip patch antenna, which can reduce costs while achieving miniaturization.

[0040] Figure 7 This paper presents a comparison of the reflection coefficient curves of the microstrip patch antenna provided in this embodiment and a traditional microstrip patch antenna. 11 Freq is the input reflection coefficient of port 1. It is the ratio of the signal reflected back from port 1 to the incident signal when incident at port 1. Freq stands for Frequency. Figure 7 As shown, the two are completely identical in terms of resonant frequency, dielectric substrate material, and thickness; the only difference lies in the patch size.

[0041] from Figure 7 It can be seen that the resonant frequency of the microstrip patch antenna provided in this embodiment is 2.45 GHz (corresponding to a wavelength λ = 122.4 mm), while the patch size of the traditional rectangular microstrip patch antenna with the same resonant frequency is 37.1 mm × 37.1 mm. Therefore, compared with the traditional rectangular microstrip patch antenna, the physical size of the microstrip patch antenna provided in this embodiment is significantly reduced.

[0042] The microstrip patch antenna provided in this embodiment has a -10dB impedance bandwidth of 2.42GHz to 2.49GHz (i.e., antenna |S 11(The frequency range corresponding to a value below −10dB) has an absolute bandwidth of 70MHz and a relative bandwidth of approximately 2.9%.

[0043] Figure 8 The gain curve of the microstrip patch antenna provided in this embodiment shows that the antenna gain is 5.59 dBi at the resonant frequency of 2.45 GHz. Within the -10 dB impedance bandwidth, the antenna gain varies little and remains above 4.9 dBi. In summary, the microstrip patch antenna provided in this embodiment has a high gain level, which can meet the requirements of practical applications.

[0044] Figure 9 This is the efficiency curve of the microstrip patch antenna provided in this embodiment. It can be seen that the antenna efficiency is 83.1% at the resonant frequency of 2.45 GHz. Within the -10 dB impedance bandwidth, the antenna efficiency is not less than 73%. In summary, the microstrip patch antenna provided in this embodiment combines the advantages of miniaturization and high radiation efficiency, and has significant advantages in practical applications.

[0045] Figure 10 and Figure 11 The images show the radiation patterns of the microstrip patch antenna provided in this embodiment at the 2.45 GHz resonant frequency in the E-plane (yoz) and H-plane (xoz), respectively. Co-Pol represents Co-Polarization (primary polarization), and X-Pol represents Cross-Polarization. It can be seen that the radiation pattern of the microstrip patch antenna provided in this embodiment is similar to that of a conventional antenna, exhibiting excellent far-field radiation characteristics.

[0046] In summary, the microstrip patch antenna provided in this embodiment is a microstrip patch antenna with a double helical slot. Based on a traditional rectangular patch, a pair of antipodal double helical slot structures are added, forming a rectangular patch with antipodal double helical slots. By setting the double helical slot structure, the current path in the patch is changed to achieve modulation of the antenna resonant frequency, effectively reducing the antenna resonant frequency while maintaining excellent radiation characteristics. The antenna has high radiation efficiency and a regular radiation pattern. The physical size of the microstrip patch antenna provided in this embodiment is much smaller than that of a traditional antenna at the same resonant frequency. Furthermore, the antenna has a gain of no less than 4.9 dBi and a radiation efficiency of no less than 73% within a 10 dB range. The microstrip patch antenna provided in this embodiment is not only simple in structure and effective, but also low in cost, showing good application prospects and achieving a reduction in electrical size while maintaining high radiation efficiency.

[0047] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A microstrip patch antenna based on an antipodal double helix groove, characterized in that, The device includes an antipodal double helix groove (1), a patch (2), a substrate (3), a ground plane (4), and a coaxial probe (5). The substrate (3) is mounted on the ground plane (4), the patch (2) is mounted on the substrate (3), the antipodal double helix groove (1) is disposed on the patch (2), and the coaxial probe (5) passes through the ground plane (4), the substrate (3), and the patch (2) in sequence. The coaxial probe (5) is used to power the patch (2), and an radio frequency electromagnetic field is generated between the patch (2) and the ground plane (4).

2. A microstrip patch antenna based on an antipodal double helix groove according to claim 1, characterized in that, The antipodal double helical groove (1) includes two antipodal distributed helical sub-grooves.

3. A microstrip patch antenna based on an antipodal double helix groove according to claim 2, characterized in that, Both of the spiral sub-grooves are Archimedean spirals.

4. A microstrip patch antenna based on an antipodal double helix groove according to claim 2, characterized in that, Each of the spiral sub-grooves includes an inner spiral (102) and an outer spiral (101).

5. A microstrip patch antenna based on an antipodal double helix groove according to claim 4, characterized in that, The spiral growth rate of the inner spiral (102) and the outer spiral (101) is less than the first preset value, and the distance between the starting point of the outer spiral (101) and its origin is less than half the width of the patch (2).

6. A microstrip patch antenna based on an antipodal double helix groove according to claim 1, characterized in that, The coaxial probe (5) includes an outer conductor (501) and an inner conductor (502). The outer conductor (501) is mounted on the ground plane (4), and the inner conductor (502) is mounted in the outer conductor (501) and passes through the substrate (3) and patch (2) in sequence.

7. A microstrip patch antenna based on an antipodal double helix groove according to claim 6, characterized in that, The ground plane (4) is provided with a circular groove, and the coaxial probe outer conductor (501) is installed on the circular groove.

8. A microstrip patch antenna based on an antipodal double helix groove according to claim 7, characterized in that, The inner conductor (502) and outer conductor (501) of the coaxial probe are coaxial.

9. A microstrip patch antenna based on an antipodal double helix groove according to claim 6, characterized in that, The characteristic impedance of the coaxial probe (5) is the second preset value.

10. A microstrip patch antenna based on an antipodal double helix groove according to claim 1, characterized in that, The substrate (3) is a substrate (3) made of a low dielectric constant material.

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