Single-Layer Single-Fed Multimode Wideband Circularly Polarized Microstrip Antenna Based on Slots and Parasitic Loading

Abstract

The present invention discloses a single-layer single-feed multi-mode broadband circularly polarized microstrip antenna based on slots and parasitic loading, which includes a dielectric substrate and a feeding probe; a metal floor is provided on the lower surface of the dielectric substrate, and a radiator is provided on the upper surface; the middle of the radiator is a circular patch, and a U-shaped slot is etched on the circular patch; a fan-shaped parasitic patch is provided on each side of the circular patch, the center of the fan-shaped parasitic patch coincides with the center of the circular patch, one of the fan-shaped parasitic patches faces the opening of the U-shaped slot, and the other fan-shaped parasitic patch faces the bottom of the U-shaped slot; the feeding probe is close to one side arm of the U-shaped slot and sequentially passes through the metal floor and the dielectric substrate to be connected to the circular patch. The present invention realizes broadband circular polarization characteristics and stable gain under the condition of single-layer single-feed.

Description

Technical Field

[0001] The present invention relates to the technical field of antennas, and in particular to a single-layer single-fed multi-mode broadband circularly polarized microstrip antenna based on slots and parasitic loading. Background Art

[0002] Circularly polarized antennas can reduce multipath interference and the Faraday rotation effect, and have the characteristic of transceiver isolation, and are widely used in wireless communication systems. Microstrip antennas are favored due to their low profile, low cost, easy processing, and planar integration, etc. However, their inherent narrowband characteristics limit their applications. In circularly polarized microstrip antennas, multilayer structures, multi-feeds, and complex feeding networks are usually adopted to achieve broadband characteristics, but at the same time, the complexity of the antenna structure and the processing cost are increased. The multi-mode technology is an effective method to expand the bandwidth. The characteristic mode theory can provide the inherent mode characteristics and physical concepts of the antenna structure, and provide useful guidance for the design of multi-mode antennas. Summary of the Invention

[0003] The purpose of the present invention is to overcome the disadvantages and deficiencies of the prior art, and provide a single-layer single-fed multi-mode broadband circularly polarized microstrip antenna based on slots and parasitic loading. By loading a U-shaped slot on a circular patch, this antenna obtains three characteristic modes that are orthogonal to each other, have a 90° phase difference, and have an end-fire radiation pattern, and realizes a relatively wide circular polarization bandwidth under the condition of single-layer single-feed. On this basis, by loading a pair of fan-shaped parasitic patches near the circular patch loaded with the U-shaped slot to introduce parasitic modes, broadband circular polarization characteristics and stable gain are realized.

[0004] The purpose of the present invention is achieved by the following technical solutions: A single-layer single-fed multi-mode broadband circularly polarized microstrip antenna based on slots and parasitic loading, including a dielectric substrate and a feeding probe; a metal ground plane is provided on the lower surface of the dielectric substrate, and a radiator is provided on the upper surface; the middle of the radiator is a circular patch, and a U-shaped slot is etched on the circular patch to realize three-mode broadband circular polarization and obtain three characteristic modes that are orthogonal to each other, have a 90° phase difference, and have an end-fire radiation pattern; a fan-shaped parasitic patch is provided on each side of the circular patch to expand the axial ratio bandwidth and improve the gain at high frequencies. The centers of the fan-shaped parasitic patches coincide with the center of the circular patch. One of the fan-shaped parasitic patches faces the opening of the U-shaped slot, and the other fan-shaped parasitic patch faces the bottom of the U-shaped slot; the feeding probe is close to one side arm of the U-shaped slot and sequentially passes through the metal ground plane and the dielectric substrate to be connected to the circular patch.

[0005] Preferably, the central axis of the U-shaped slot is collinear with the central axis of the circular patch.

[0006] Preferably, the lengths of the two side arms of the U-shaped slot are equal or unequal.

[0007] Preferably, the two sector parasitic patches are centrosymmetric about the center of the dielectric substrate.

[0008] Preferably, the lengths of the two sector parasitic patches are not equal.

[0009] Preferably, the central axes of the sector parasitic patches are not collinear with the central axis of the U-shaped slot.

[0010] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0011] 1. By loading a U-shaped slot on the circular patch and a pair of sector parasitic patches on both sides of the circular patch, the antenna of the present invention realizes broadband circular polarization characteristics and stable gain under the condition of single-layer single-feed.

[0012] 2. The antenna of the present invention adopts U-shaped slot and sector parasitic patch loading, and realizes |S 11 | < -10 dB impedance bandwidth of 34.08%, AR < 3 axial ratio bandwidth of 32.6%, and effective overlapping bandwidth of 31.96%; the gain is stable within the working bandwidth, and the gain fluctuation within 85% of the working frequency band is less than 0.5 dB, and the maximum gain is 6.78 dBic, obtaining good broadband left-handed circular polarization characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a three-dimensional structure schematic diagram of the single-layer single-feed multimode broadband circular polarization microstrip antenna according to an embodiment of the present invention.

[0014] Figure 2 It is a top view structure schematic diagram of the single-layer single-feed multimode broadband circular polarization microstrip antenna according to an embodiment of the present invention.

[0015] Figure 3 It is a left view structure schematic diagram of the single-layer single-feed multimode broadband circular polarization microstrip antenna according to an embodiment of the present invention.

[0016] Figure 4 It is a simulation S-parameter diagram of the single-layer single-feed multimode broadband circular polarization microstrip antenna according to an embodiment of the present invention.

[0017] Figure 5 It is a simulation axial ratio curve diagram of the single-layer single-feed multimode broadband circular polarization microstrip antenna according to an embodiment of the present invention.

[0018] Figure 6 It is a simulation gain curve diagram of the single-layer single-feed multimode broadband circular polarization microstrip antenna according to an embodiment of the present invention.

[0019] Figure 7 It is the radiation pattern of the single-layer single-feed multimode broadband circular polarization microstrip antenna according to an embodiment of the present invention in the xoz plane at 4.75 GHz.

[0020] Figure 8 The radiation pattern in the yoz plane at 4.75 GHz of the single-layer single-feed multi-mode broadband circularly polarized microstrip antenna according to the embodiment of the present invention.

[0021] Figure 9 The radiation pattern in the xoz plane at 5.5 GHz of the single-layer single-feed multi-mode broadband circularly polarized microstrip antenna according to the embodiment of the present invention.

[0022] Figure 10 The radiation pattern in the yoz plane at 5.5 GHz of the single-layer single-feed multi-mode broadband circularly polarized microstrip antenna according to the embodiment of the present invention.

[0023] Figure 11 The radiation pattern in the xoz plane at 6.25 GHz of the single-layer single-feed multi-mode broadband circularly polarized microstrip antenna according to the embodiment of the present invention.

[0024] Figure 12 The radiation pattern in the yoz plane at 6.25 GHz of the single-layer single-feed multi-mode broadband circularly polarized microstrip antenna according to the embodiment of the present invention.

[0025] Figure 13 The top view size structure diagram of the single-layer single-feed multi-mode broadband circularly polarized microstrip antenna according to the embodiment of the present invention.

[0026] Wherein, 1 - dielectric substrate, 2 - circular patch, 3 - U-shaped slot, 4 - fan-shaped parasitic patch, 5 - feeding probe. Detailed implementation manners

[0027] The present invention will be further described in detail below in conjunction with embodiments and the accompanying drawings, but the implementation manners of the present invention are not limited thereto.

[0028] The microstrip antenna processed by PCB technology has the characteristics of small volume, light weight, low cost, and easy planar integration; circularly polarized antennas have broad application prospects in satellite, mobile communication, and sensing systems. Compared with linearly polarized antennas, circularly polarized antennas have the advantages of being insensitive to the axial rotation of the antenna, small delay propagation, anti-multipath interference, and Faraday rotation. In addition, broadband antennas can operate in a relatively wide frequency range to adapt to different working scenarios; antennas with stable broadband gain can enable stable wireless communication of the antenna within a wide frequency band. And single-layer single-feed makes the antenna structure simple and has good mechanical stability. Therefore, this embodiment provides a single-layer single-feed multi-mode broadband circularly polarized microstrip antenna based on slot and parasitic loading.

[0029] Such as Figures 1 - 3As shown, the single-layer single-feed multi-mode broadband circularly polarized microstrip antenna based on slots and parasitic loading provided in this embodiment includes a dielectric substrate 1 and a feeding probe 5; the dielectric substrate 1 uses Rogers AD250C, with a dielectric constant of 2.5, a loss tangent of 0.0013, and a thickness of 6.3 mm; a metal floor is provided on the lower surface of the dielectric substrate 1, and a radiator is provided on the upper surface; the middle of the radiator is a circular patch 2, and a U-shaped slot 3 is etched on the circular patch 2 to achieve triple-mode broadband circular polarization and obtain three characteristic modes that are orthogonal to each other, have a 90° phase difference, and have an end-fire radiation pattern; the two side arms of the U-shaped slot 3 are of equal length by default, and can also be unequal if necessary; a sector-shaped parasitic patch 4 is provided on each side of the circular patch 2 to expand the axial ratio bandwidth and improve the gain at high frequencies. The center of the sector-shaped parasitic patch 4 coincides with the center of the circular patch 2. One of the sector-shaped parasitic patches 4 faces the opening of the U-shaped slot 3, and the other sector-shaped parasitic patch 4 faces the bottom of the U-shaped slot 3; the two sector-shaped parasitic patches 4 are centrosymmetric about the center of the dielectric substrate 1, and the lengths of the two sector-shaped parasitic patches 4 are equal by default, and can also be unequal if necessary; the feeding probe 5 is close to one side arm of the U-shaped slot 3 and sequentially passes through the metal floor and the dielectric substrate 1 to be connected to the circular patch 2.

[0030] Specifically, in this embodiment, the central axis of the U-shaped slot 3 is collinear with the central axis of the circular patch 2; the central axis of the sector-shaped parasitic patch 4 is not collinear with the central axis of the U-shaped slot 3.

[0031] Figure 4 This is the S-parameter simulation curve graph of the above single-layer single-feed multi-mode broadband circularly polarized microstrip antenna in this embodiment. It can be seen from the graph that the bandwidth of the antenna |S 11 | < -10 dB is about 34.08% (4.6 - 6.49 GHz), which is applied to the C band.

[0032] Figure 5 This is the axial ratio simulation curve graph of the above single-layer single-feed multi-mode broadband circularly polarized microstrip antenna in the positive z-axis direction. It can be seen from the graph that the bandwidth of the antenna AR < 3 dB is about 32.6% (4.57 - 6.35 GHz); the antenna simultaneously satisfies |S 11 | < -10 dB and the bandwidth of AR < 3 dB is about 31.96% (4.6 - 6.35 GHz), achieving the circularly polarized characteristic of a wide frequency band.

[0033] Figure 6This is the simulation curve graph of the gain of the above-mentioned single-layer single-feed multi-mode broadband circularly polarized microstrip antenna of this embodiment in the positive z-axis direction. It can be seen from the graph that the gain of the antenna is stable within the working bandwidth, and the gain fluctuation is less than 0.5 dB within 85% of the working bandwidth; the highest gain of the antenna is 6.78 dBic, and the lowest gain is 4.41 dBic.

[0034] Figure 7 and Figure 8 This is the radiation pattern of the above-mentioned single-layer single-feed multi-mode broadband circularly polarized microstrip antenna of this embodiment in the xoz plane and yoz plane at 4.75 GHz. It can be seen from the graph that the main polarization of the antenna at this frequency point is left-handed circular polarization, with good directional circular polarization radiation characteristics and cross polarization less than -10 dB.

[0035] Figure 9 and Figure 10 This is the radiation pattern of the above-mentioned single-layer single-feed multi-mode broadband circularly polarized microstrip antenna of this embodiment in the xoz plane and yoz plane at 5.5 GHz. It can be seen from the graph that the main polarization of the antenna at this frequency point is left-handed circular polarization, with good directional circular polarization radiation characteristics and cross polarization less than -10 dB.

[0036] Figure 11 and Figure 12 This is the radiation pattern of the above-mentioned single-layer single-feed multi-mode broadband circularly polarized microstrip antenna of this embodiment in the xoz plane and yoz plane at 6.25 GHz. It can be seen from the graph that the main polarization of the antenna at this frequency point is left-handed circular polarization, with good directional circular polarization radiation characteristics and cross polarization less than -10 dB.

[0037] Figure 13 This is the top view size structure diagram of the above-mentioned single-layer single-feed multi-mode broadband circularly polarized microstrip antenna of this embodiment. The specific dimensions of the antenna are:

[0038] Lg = Wg = 50 mm, R0 = 8 mm, R1 = 4 mm, R2 = R1 + u, u = 1 mm, ls1 = ls2 = 3.5 mm,

[0039] R3 = R0 + g, g = 3.5 mm, R4 = R3 + wa, wa = 2.4 mm, β1 = β2 = 58 deg, γ = 77 deg

[0040] In summary, the antenna of the present invention realizes the tri-mode broadband circular polarization characteristic by loading a U-shaped slot on the circular patch; then, a pair of sector parasitic patches are loaded on both sides of the circular patch to introduce a parasitic mode to regulate the amplitude and phase difference of the two orthogonal components (Phi component and Theta component) of the high-frequency electric field in the far field, thereby expanding the axial ratio bandwidth at high frequencies. Under the conditions of a single-layer dielectric substrate and single-probe feeding, the antenna finally achieves an impedance matching bandwidth of approximately 34.08%, an axial ratio bandwidth of approximately 32.6%, and an overlapping bandwidth of the two of approximately 31.96%; within the overlapping bandwidth, the antenna gain is stable, with a gain fluctuation of less than 0.5 dB within 85% of the overlapping bandwidth, and the maximum gain is 6.78 dBic, realizing a single-layer single-fed multi-mode broadband circularly polarized antenna with a stable gain within the band.

[0041] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A single-layer single-feed multimode broadband circularly polarized microstrip antenna based on slots and parasitic loading, characterized in that, It includes a dielectric substrate (1) and a feeding probe (5); a metal ground plane is provided on the lower surface of the dielectric substrate (1), and a radiator is provided on the upper surface; the middle of the radiator is a circular patch (2), and a U-shaped slot (3) is etched on the circular patch (2) to achieve triple-mode broadband circular polarization and obtain three characteristic modes that are orthogonal to each other, have a 90° phase difference, and have an end-fire radiation pattern. A sector parasitic patch (4) is provided on each side of the circular patch (2) to expand the axial ratio bandwidth and improve the gain at high frequencies. The center of the sector parasitic patch (4) coincides with the center of the circular patch (2). One of the sector parasitic patches (4) faces the opening of the U-shaped slot (3), and the other sector parasitic patch (4) faces the bottom of the U-shaped slot (3); the feeding probe (5) is close to one side arm of the U-shaped slot (3) and sequentially passes through the metal ground plane and the dielectric substrate (1) to be connected to the circular patch (2).

2. The single-layer single-feed multi-mode broadband circularly polarized microstrip antenna based on slots and parasitic loading according to claim 1, characterized in that The central axis of the U-shaped slot (3) is collinear with the central axis of the circular patch (2).

3. The single-layer single-feed multi-mode broadband circularly polarized microstrip antenna based on slots and parasitic loading according to claim 2, wherein The two side arms of the U-shaped slot (3) are of equal or unequal lengths.

4. The single-layer single-feed multi-mode broadband circularly polarized microstrip antenna based on slots and parasitic loading according to claim 3, characterized in that The two sector parasitic patches (4) are centrosymmetric about the center of the dielectric substrate (1).

5. The single-layer single-feed multi-mode broadband circularly polarized microstrip antenna based on slots and parasitic loading according to claim 3, characterized in that, The lengths of the two sector parasitic patches (4) are unequal.

6. The single-layer single-feed multi-mode broadband circularly polarized microstrip antenna based on slots and parasitic loading according to claim 4 or 5, characterized in that, The central axis of the sector parasitic patch (4) is not collinear with the central axis of the U-shaped slot (3).

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