An X-band wide-bandwidth circularly polarized conformal microstrip antenna

Abstract

The present invention belongs to the field of wireless communications technology, and particularly relates to an X-band wide-bandwidth beam circularly polarized conformal microstrip antenna. The technical solution is as follows: an X-band wide-bandwidth beam circularly polarized conformal microstrip antenna comprising a first dielectric substrate and a second dielectric substrate. The first dielectric substrate is printed with an antenna pattern and four perturbation metal patterns surrounding the antenna pattern. The second dielectric substrate is also printed with four perturbation metal patterns. Short-circuit probes are loaded onto the four perturbation metal patterns on the first dielectric substrate. The present invention provides an X-band wide-bandwidth beam circularly polarized conformal microstrip antenna that achieves X-band circularly polarized radiation characteristics and wide-bandwidth beam characteristics.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless communications, and in particular relates to an X-band wide-bandwidth beam circularly polarized conformal microstrip antenna. Background Art

[0002] In recent years, demand for carrier-conformal antennas has been increasing. Microstrip antennas have been widely used due to their small size, low profile, and ease of conforming to carriers. However, microstrip antennas generally have narrow bandwidth. Circularly polarized antennas are often used for communications between carriers and between carriers and satellites, and require a 3dB axial ratio beam coverage of 120° or greater. However, circularly polarized antennas that achieve this beam coverage typically have narrow bandwidth. Therefore, circularly polarized conformal microstrip antennas that can simultaneously achieve wide-bandwidth beams hold great promise for future applications.

[0003] Microstrip antennas achieve bandwidth expansion primarily through the use of matching branches and multilayer dielectric coupling. Matching branches can broaden the antenna's operating frequency band by adjusting the antenna's impedance matching; multilayer dielectric coupling can stimulate multiple resonance points within a wide frequency band, thereby widening the antenna's operating bandwidth. Microstrip antennas achieve circularly polarized radiation characteristics primarily through single-feed-point and multi-feed-point technologies. Single-feed-point technology primarily utilizes geometric perturbations on the antenna's radiating patch, resulting in a narrow 3dB axial ratio bandwidth. Multi-feed-point technology utilizes a feed network to feed the antenna's radiating patch at multiple points to stimulate circularly polarized radiation, resulting in a wider 3dB axial ratio bandwidth.

[0004] For carrier conformal antennas, the feeding network of multi-feed point circularly polarized antennas will occupy limited resources on the carrier surface, and the frequency band of single-feed point circularly polarized antennas is relatively narrow. Summary of the Invention

[0005] In order to solve the above problems existing in the prior art, the object of the present invention is to provide an X-band wide bandwidth beam circularly polarized conformal microstrip antenna to achieve X-band circular polarization radiation characteristics and wide bandwidth beam characteristics.

[0006] The technical solution adopted in the present invention is:

[0007] An X-band wide-bandwidth beam circularly polarized conformal microstrip antenna comprises a first dielectric substrate and a second dielectric substrate. The first dielectric substrate is printed with an antenna pattern and four perturbation metal patterns located around the antenna pattern. The second dielectric substrate is also printed with four perturbation metal patterns. Short-circuit probes are loaded on the four perturbation metal patterns on the first dielectric substrate.

[0008] The antenna pattern is printed on the first dielectric substrate of the present invention, which can realize X-band circular polarization radiation characteristics.

[0009] Using a coaxial probe for feeding will cause the input impedance to exhibit inductive reactance characteristics, resulting in input-output mismatch and a large reflection coefficient. In the present invention, a second dielectric substrate is covered on the first dielectric substrate, and perturbation metal patterns are provided on both the first and second dielectric substrates to form a capacitive structure to offset the inductive reactance characteristics of the probe feeding and broaden the impedance bandwidth.

[0010] The four perturbation metal patterns on the first dielectric substrate are loaded with short-circuit probes, which can effectively broaden the circularly polarized 3dB axial ratio beam bandwidth.

[0011] As a preferred solution of the present invention, the first dielectric substrate is provided with a through hole near the geometric center, a feeding probe is passed through the through hole, and the feeding probe is connected to the antenna pattern.

[0012] As a preferred solution of the present invention, the dielectric constants of the first dielectric substrate and the second dielectric substrate are both 2.2, and the loss tangents are both 0.001; and the models of the first dielectric substrate and the second dielectric substrate are both Rogers5880.

[0013] As a preferred solution of the present invention, air with a height of 1 mm is filled between the first dielectric substrate and the second dielectric substrate.

[0014] As a preferred solution of the present invention, the thickness of the first dielectric substrate is 1.575 mm.

[0015] As a preferred solution of the present invention, the thickness of the second dielectric substrate is 1 mm.

[0016] As a preferred solution of the present invention, the antenna pattern includes a square loop antenna and an arc-shaped delay line connected to the inside of the loop antenna.

[0017] As a preferred embodiment of the present invention, the circumference of the loop antenna is equal to the wavelength, and the length of the arc-shaped delay line is 1 / 4 wavelength. For the loop antenna, when the wavelength is equal to the circumference, the circular polarization mode TM11 of the loop antenna can be effectively excited. For the arc-shaped delay line, when the length of the arc-shaped delay line is 1 / 4 wavelength, a continuous current with a phase difference of 90° is supplied to the loop antenna, achieving right-hand circular polarization.

[0018] As a preferred solution of the present invention, it also includes a frame, the bottom of the frame is connected to a radio frequency connector, the first layer of dielectric substrate and the second layer of dielectric substrate are arranged in the frame, and the upper part of the frame is connected to an antenna cover.

[0019] As a preferred solution of the present invention, the material of the antenna cover is polytetrafluoroethylene, with a dielectric constant of 2.0-2.2 and a tangent loss factor of 0.001.

[0020] The beneficial effects of the present invention are:

[0021] 1. The antenna pattern is printed on the first dielectric substrate of the present invention, which can achieve X-band circularly polarized radiation characteristics.

[0022] 2. Using a coaxial probe for feeding results in an inductive input impedance, leading to input-output mismatch and a large reflection coefficient. This invention overlays a second dielectric substrate on the first dielectric substrate, and provides perturbation metal patterns on both the first and second dielectric substrates. This creates a capacitive structure that offsets the inductive characteristics of the probe feed and broadens the impedance bandwidth.

[0023] 3. The four perturbation metal patterns on the first dielectric substrate are loaded with short-circuit probes, which can effectively broaden the circularly polarized 3dB axial ratio beamwidth. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of the present invention;

[0025] Figure 2 It is a main view of the first dielectric substrate;

[0026] Figure 3 is the main view of the antenna pattern;

[0027] Figure 4 Schematic diagram of the structure of the second dielectric substrate;

[0028] Figure 5 This is an exploded diagram of the antenna;

[0029] Figure 6 This is the antenna simulation model diagram;

[0030] Figure 7 It is a curve diagram of return loss parameters;

[0031] Figure 8 is the standing wave ratio curve;

[0032] Figure 9 It is the 3dB axial ratio bandwidth curve;

[0033] Figure 10 It is the 3dB axial ratio beam curve;

[0034] Figure 11 is the XOZ plane antenna gain pattern;

[0035] Figure 12 It is the YOZ plane antenna gain diagram;

[0036] Figure 13 is the antenna gain pattern;

[0037] Figure 14 This is the antenna assembly diagram.

[0038] In the figure: 1-first dielectric substrate; 2-second dielectric substrate; 3-antenna pattern; 4-perturbation metal pattern; 5-short-circuit probe; 6-feed probe; 7-frame; 8-RF connector; 9-radome; 31-loop antenna; 32-arc delay line. DETAILED DESCRIPTION

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0040] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. It should be noted that the embodiments of the present invention and the features therein may be combined with each other unless there is a conflict.

[0041] like Figures 1 to 4 As shown, the X-band wide-bandwidth beam circularly polarized conformal microstrip antenna of this embodiment includes a first dielectric substrate 1 and a second dielectric substrate 2. The first dielectric substrate 1 is printed with an antenna pattern 3 and four perturbation metal patterns 4 surrounding the antenna pattern 3. The second dielectric substrate 2 is also printed with four perturbation metal patterns 4. Shorting probes 5 are attached to the four perturbation metal patterns 4 on the first dielectric substrate 1. A through-hole is provided near the geometric center of the first dielectric substrate 1, through which a feeding probe 6 is inserted. The feeding probe 6 is connected to the antenna pattern 3.

[0042] The antenna pattern 3 is printed on the first dielectric substrate 1 of the present invention, which can achieve X-band circularly polarized radiation characteristics.

[0043] Using a coaxial probe for feeding will cause the input impedance to exhibit inductive reactance characteristics, resulting in input-output mismatch and a large reflection coefficient. In the present invention, a second dielectric substrate 2 is covered on a first dielectric substrate 1, and a perturbation metal pattern 4 is provided on both the first dielectric substrate 1 and the second dielectric substrate 2. This will form a capacitive structure to offset the inductive reactance characteristics of the probe feeding and broaden the impedance bandwidth.

[0044] The four perturbation metal patterns 4 on the first dielectric substrate 1 are all loaded with short-circuit probes 5, which can effectively broaden the circularly polarized 3 dB axial ratio beam bandwidth.

[0045] Specifically, the first dielectric substrate 1 and the second dielectric substrate 2 are both Rogers 5880 low-loss dielectric substrates with a dielectric constant of 2.2 and a loss tangent of 0.001.

[0046] Among them, the thickness of the first dielectric substrate 1 is 1.575 mm, the printed antenna pattern 3 and four perturbation metal patterns 4 located around the antenna pattern 3 are printed on the upper layer of the first dielectric substrate 1, and the bottom layer of the first dielectric substrate 1 is entirely made of metal foil as the antenna ground plane.

[0047] The thickness of the second dielectric substrate 2 is 1 mm. Four perturbation metal patterns 4 are printed on the upper layer of the second dielectric substrate 2. The second dielectric substrate 2 serves as a covering layer of the first antenna structure. Air with a height of h is filled between the first dielectric substrate 1 and the second dielectric substrate 2.

[0048] Specifically, if Figure 3 As shown, the antenna pattern 3 includes a square loop antenna 31 and an arc-shaped delay line 32 connected to the inside of the loop antenna 31. The circumference of the loop antenna 31 is equal to the wavelength; the length of the arc-shaped delay line 32 is 1 / 4 wavelength.

[0049] For the loop antenna 31, when the circumference of the loop antenna 31 is equal to the wavelength, the circular polarization mode of the loop antenna 31 can be effectively excited. The circumference L1 of the loop antenna 31 is calculated by formula (1):

[0050] (1);

[0051] Where c is the speed of light in free space, d1 is the length of the outer ring of the loop antenna 31, d2 is the length of the inner ring of the loop antenna 31, and ε e is the dielectric constant of the dielectric substrate, f TM1 is the frequency in circular polarization mode.

[0052] Then, based on the selected width of the loop antenna 31 , the outer side length d1 of the loop antenna 31 and the inner side length d2 of the loop antenna 31 are calculated.

[0053] When the length of arc-shaped delay line 32 is 1 / 4 wavelength, a continuous current with a phase difference of 90° is provided to loop antenna 31, achieving right-hand circular polarization. In the present invention, arc-shaped delay line 32 is a three-quarter arc. The length L2 of arc-shaped delay line 32 is calculated using Equation (2).

[0054] (2);

[0055] Where r2 is the outer diameter of the arc, r1 is the inner diameter of the arc, c is the speed of light in free space, and ε e is the dielectric constant of the dielectric substrate, and f is the frequency.

[0056] Then, according to the selected width of the arc-shaped delay line 32 , the arc inner diameter r1 and the arc outer diameter r2 of the arc-shaped delay line 32 are calculated.

[0057] The present invention also includes a frame 7, with an RF connector 8 connected to the bottom. The first and second dielectric substrates 1 and 2 are mounted within the frame 7, and a radome 9 is attached to the top of the frame 7. The antenna is housed within the aluminum alloy frame 7 and secured to the metal housing using M2.5 screws. All screws are reinforced with threadlocker, ensuring excellent reliability. The radome 9 is made of polytetrafluoroethylene, which has a dielectric constant of approximately 2.1, a tangent loss factor of 0.001, and a temperature resistance of up to 200°C for long-term use. The overall dimensions of the antenna are 78 mm × 55 mm × 13 mm.

[0058] Assume that the size is W (about 1 / 2 wavelength, corresponding to the electrical length W e ) is a rectangular patch circularly polarized microstrip antenna with an operating wavelength of λ. Its horizontal electric field component E θ and the vertical electric field component E φ Completely vertical, the angle is 90°. According to Huygens wave propagation theory and antenna theory:

[0059] (3);

[0060] (4);

[0061] in, θ W represents the angle between the electric field vector of the rectangular circularly polarized microstrip antenna and the horizontal direction. e is the electrical length of the antenna, that is, the ratio of the physical length of the antenna to the wavelength.

[0062] Then the 3dB beamwidth of AR is:

[0063] (5);

[0064] The electrical length is W e for:

[0065] (6);

[0066] Among them, ε reff is the effective dielectric constant of the dielectric substrate, ε r is the dielectric constant of the dielectric substrate, and h is the thickness of the dielectric substrate.

[0067] From formula (5), we can see that the 3dB beamwidth is the electrical length W eand the operating wavelength λ. When the operating wavelength is determined, the 3dB beamwidth is only related to the electrical length. Equation (6) shows that the electrical length of the rectangular patch microstrip antenna is related to the effective dielectric constant and thickness of the selected dielectric substrate.

[0068] To expand the antenna's impedance bandwidth, the present invention selected Rogers 5800, a dielectric substrate with a low effective dielectric constant of 2.2 and a common thickness of 1.575 mm. The electrical length dimension is essentially determined by the chosen dielectric substrate. Therefore, adding a shorting probe 5 to the antenna introduces an inductive component, which, according to transmission line theory, effectively changes the electrical length. By adding the shorting probe 5 in the appropriate position and size, an even better 3dB beamwidth can be achieved.

[0069] Simulation results and analysis:

[0070] Modeling and simulation are carried out in the electromagnetic simulation software HFSS. Figure 6 shown.

[0071] The antenna dimensions after simulation optimization are: W=48mm, w1=8.4mm, w2=6.4mm, w r1 =1.2mm, (p x , p y )=(2.5mm, 0mm), (p x1 , p y1 )=(5mm, 2.8mm), the other three short-circuit probes 5 are rotated 90° in sequence, d1=7.4mm, d2=5.7mm, r2=2.2mm, r1=0.4mm, w f =1mm, w3=8.6mm, w4=7mm, w r2 =1.6mm, h=1mm.

[0072] Figure 7 is the return loss parameter curve of the antenna, Figure 7 It can be seen that the return loss is less than -10dB in the frequency range of 7.79GHz to 10.07GHz, and the impedance relative bandwidth is 25.33%. Figure 8 is the standing wave ratio curve of the antenna, Figure 8 It can be seen that the standing wave ratio is less than 2 in the frequency range of 7.77GHz to 10.17GHz. Figure 7 and Figure 8 Where m1, m2, and m3 are the selected characteristic points, which are the return loss and standing wave ratio of the antenna at frequencies of 8.5 GHz, 9 GHz, and 9.5 GHz.

[0073] Figure 9 is the 3dB axial ratio bandwidth curve of the antenna when Theat=0° and Phi=0°, Figure 9It can be seen that the axial ratio of the antenna is less than 3dB in the frequency range of 8.4GHz to 9.72GHz, and the axial ratio relative bandwidth is 14.67%. Figure 9 Here, m1, m2, and m3 are selected characteristic points, which are the 3dB axial ratio bandwidths when Theat=0° and Phi=0° when the antenna frequencies are 8.5G, 9G, and 9.5G. Figure 10 The 3dB axial ratio beam curve for the antenna at a center frequency of 9 GHz and Phi = 0° is shown in the figure. The axial ratio is less than 3dB in the range (-65.66° to 51.59°), covering a beam range of 117°. Figure 10 Point m1 is the selected feature point, which represents the axial ratio of the antenna when Phi=0° and Theat=0°.

[0074] Figure 11 and Figure 12 The radiation patterns for the antenna in the XOZ and YOZ planes, respectively, are shown when operating at 9 GHz. The red curve represents the right-hand polarization gain, and the blue curve represents the left-hand polarization gain. At Phi = 0° and Theat = 0°, the antenna gain is 8.89 dB, the cross-polarization is less than -25 dB, and the -3 dB beamwidth is greater than 120°. Figure 11 and Figure 12 Point m1 is the gain of the antenna when Phi=0° and Theat=0°, points m2 and m3 are the characteristic points of the antenna in the YOZ plane radiation pattern with gain ≥-3dB, and points m4 and m5 are the characteristic points of the antenna in the XOZ plane radiation pattern with gain ≥-3dB.

[0075] Figure 13 The gain of the antenna varies with frequency when Phi=0° and Theat=0°. It can be seen from the figure that the gain is greater than 7dB@(Phi=0°&Theat=0°) within the antenna operating frequency band. Figure 13 Where m1, m2, and m3 are the selected characteristic points, which are the gain values of the antenna at Theat=0° and Phi=0° at the frequency points of 8.5G, 9G, and 9.5G.

[0076] Figure 14 This is a 3D schematic diagram of the antenna radiation direction, that is, the antenna radiates outward in a semicircular pattern, covering 360° horizontally and 90° in elevation.

[0077] Physical processing and testing:

[0078] The HFSS model was imported into AD software for printed circuit board production. The first dielectric substrate 1 and the second dielectric substrate 2 were made of Rogers 5880 material, with the thickness of the first dielectric substrate 1 being 1.575 mm and the thickness of the second dielectric substrate 2 being 1 mm.

[0079] The four vias on the periphery of the first dielectric layer are plugged with copper paste, contacting the top metal patch and the bottom ground layer. The middle via is a plated via for soldering probes. The second dielectric substrate 2 has only the top metal patch, leaving the Rogers 5880 exposed on the bottom layer.

[0080] The actual antenna consists of an antenna radiation unit (the first dielectric substrate 1), an antenna covering (the second dielectric substrate 2), an antenna cover 9, a frame 7, a 1mm gasket and a connector.

[0081] The present invention is not limited to the above-mentioned optional implementation modes. Anyone can derive other forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, any technical solution that falls within the scope defined by the claims of the present invention falls within the scope of protection of the present invention.

Claims

1. An X-band wide-bandwidth circularly polarized conformal microstrip antenna, characterized by: The invention comprises a first dielectric substrate (1) and a second dielectric substrate (2), wherein an antenna pattern (3) and four perturbation metal patterns (4) located around the antenna pattern (3) are printed on the first dielectric substrate (1), and four perturbation metal patterns (4) are also printed on the second dielectric substrate (2); and short-circuit probes (5) are loaded on the four perturbation metal patterns (4) on the first dielectric substrate (1); The first dielectric substrate (1) is provided with a through hole near the geometric center, a feeding probe (6) is passed through the through hole, and the feeding probe (6) is connected to the antenna pattern (3); The antenna pattern (3) includes a square loop antenna (31) and an arc-shaped delay line (32) connected to the inside of the loop antenna (31); the circumference of the loop antenna (31) is equal to the wavelength; and the length of the arc-shaped delay line (32) is 1 / 4 of the wavelength.

2. The X-band wide bandwidth circularly polarized conformal microstrip antenna according to claim 1, characterized in that: The dielectric constants of the first dielectric substrate (1) and the second dielectric substrate (2) are both 2.2, and the loss tangents are both 0.001; the models of the first dielectric substrate (1) and the second dielectric substrate (2) are both Rogers 5880.

3. The X-band wide bandwidth circularly polarized conformal microstrip antenna according to claim 1, characterized in that: Air with a height of 1 mm is filled between the first dielectric substrate (1) and the second dielectric substrate (2).

4. The X-band wide bandwidth circularly polarized conformal microstrip antenna according to claim 1, characterized in that: The thickness of the first dielectric substrate (1) is 1.575 mm.

5. The X-band wide bandwidth circularly polarized conformal microstrip antenna according to claim 1, characterized in that: The thickness of the second dielectric substrate (2) is 1 mm.

6. The X-band wide bandwidth circularly polarized conformal microstrip antenna according to claim 1, characterized in that: It also includes a frame (7), the bottom of the frame (7) is connected to a radio frequency connector (8), the first layer of dielectric substrate (1) and the second layer of dielectric substrate (2) are arranged in the frame (7), and the upper part of the frame (7) is connected to an antenna cover (9).

7. The X-band wide bandwidth circularly polarized conformal microstrip antenna according to claim 6, characterized in that: The material of the antenna cover (9) is polytetrafluoroethylene, with a dielectric constant of 2.0-2.2 and a tangent loss factor of 0.001.

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