Low-profile broadband large-sweep-angle patch antenna

Abstract

The invention discloses a low-profile broadband large-sweep-angle patch antenna. The patch antenna comprises a first dielectric layer; a second dielectric layer; a third dielectric layer; a radiation layer; the radiation layer comprises a main radiation patch, and the edge of the main radiation patch is provided with a coupling notch; the feed network is arranged in the third dielectric layer; a feed probe; the feed probe comprises a feed probe vertical branch and a feed probe horizontal branch; the other end of the vertical branch of the feed probe is electrically connected with the output port of the feed network, the horizontal branch of the feed probe and the main radiation patch of the radiation layer are coplanar, the front end of the horizontal branch of the feed probe is located in the coupling notch of the main radiation patch to form a coupling gap, and the feed probe feeds the main radiation patch through the coupling gap. According to the low-profile broadband large-sweep-angle patch antenna, the H-plane scanning angle can reach 0 + / -60 degrees, the working frequency band covers 6.8-12.4 GHz, the working bandwidth reaches 58.3%, and meanwhile the low-profile broadband large-sweep-angle patch antenna has the advantages of being low in profile and stable in structure.

Description

Technical Field

[0001] The invention relates to a patch antenna structure, belonging to the technical field of patch antennas, and in particular to a broadband patch antenna using an L-shaped probe for feeding. Background Art

[0002] As a patch antenna, using L-probe feeding is one of the most effective ways to improve the antenna's working bandwidth and radiation efficiency. However, even so, its normal working bandwidth can only reach about 35%, and the working bandwidth at large scanning angles will be further reduced. At the same time, since the probe and the radiating patch of the traditional L-probe feeding structure are not in the same plane, the antenna structure has a high profile and is difficult to process, and is no longer applicable in many application scenarios. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a low-profile, wide-band, large-scan-angle patch antenna that reduces the antenna profile height and reduces the difficulty of processing in view of the deficiencies in the above-mentioned prior art.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: A low-profile, wide-band, large-sweep-angle patch antenna, comprising: a first dielectric layer; A second dielectric layer, located below the first dielectric layer; A third dielectric layer located below the second dielectric layer; A radiation layer; located between the first dielectric layer and the second dielectric layer; the radiation layer comprises a main radiation patch, and a coupling notch is provided at the edge of the main radiation patch; A feeding circuit is arranged in the third dielectric layer; A feeding probe; the feeding probe comprises a feeding probe vertical branch and a feeding probe horizontal branch, one end of the feeding probe vertical branch is connected to one end of the feeding probe horizontal branch; the other end of the feeding probe vertical branch is electrically connected to the output port of the feeding circuit; the feeding probe vertical branch is arranged in the second dielectric layer, the feeding probe horizontal branch is coplanar with the main radiation patch of the radiation layer, the front end of the feeding probe horizontal branch is located in the coupling slot of the main radiation patch to form a coupling gap, and the feeding probe feeds the main radiation patch through the coupling gap.

[0005] The coupling notch arranged at the edge of the main radiation patch is a stepped groove including a small width groove and a large width groove; the feeding probe also includes a lateral branch located near the end of the horizontal branch of the feeding probe, and the lateral branch is located in the large width groove.

[0006] The horizontal branches and transverse branches of the feeding probe are both rectangular strip structures.

[0007] The radiating layer also includes four parasitic patches.

[0008] The parasitic patches are square and are respectively located at the four corners of the antenna radiation layer.

[0009] The first dielectric layer includes a first dielectric layer upper substrate and a first dielectric layer lower substrate.

[0010] The lower substrate of the first dielectric layer is made of PMI foam material.

[0011] The third dielectric layer comprises, from top to bottom, an upper metal ground, a third dielectric layer upper substrate, a third dielectric layer lower substrate and a lower metal ground; the feed network is arranged between the third dielectric layer upper substrate and the third dielectric layer lower substrate.

[0012] The feeding network is composed of a second-order Wilkinson power divider and a broadband 180° phase shifter in cascade connection.

[0013] The feeding network also includes a phase-stabilizing structure, which consists of two wires with a length difference of λ / 2 transmission line, and two sets of spacing are loaded on the shorter transmission line λ / 2 open line and short line, forming an I-shaped structure, the length of the open line and the length of the short line are both λ / 8.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. A first dielectric layer is provided above the radiation layer as a wide-angle matching layer, which reduces the active impedance change during angle scanning, thereby improving the active standing wave characteristics of the antenna at large scanning angles. The structural form of the traditional L-type probe feeding is that the L-type probe is out of plane with the radiation layer. Specifically, the horizontal branch of the L-type probe is located below the main radiation patch, and air or dielectric material is filled between the two. Compared with the out-of-plane L-type probe feeding, the present invention adopts a coplanar L-probe feeding method, that is, the horizontal branch of the probe is coplanar with the radiation layer. At this time, the vertical branch of the L-type probe produces an equivalent inductance, and the gap between the horizontal branch of the L-type probe and the main radiation patch on the radiation layer produces an equivalent capacitance. The two interact to produce a new resonance point, thereby expanding the working bandwidth. The coplanar L-type probe feeding in the present invention retains the broadband characteristics of the traditional L-type probe feeding while reducing the antenna profile height and reducing the processing difficulty.

[0015] 2. The horizontal branch of the traditional L-type probe is a rectangular strip structure, which makes the gap width between the horizontal branch and the main radiation patch a certain value. The present invention loads a transverse branch near the end of the horizontal branch of the probe to form an inverted T-shaped structure. On the one hand, by adjusting the position and length of the transverse branch, the gap width between the horizontal branch of the L probe and the main radiation patch can be adjusted. Specifically, the gap width between the transverse branch and the main radiation patch can be different from the gap width between the rest of the horizontal branch of the L probe and the main radiation patch, which improves the freedom of the antenna structure and realizes the flexible adjustment of the equivalent capacitance between the horizontal branch of the probe and the main radiation patch, thereby adjusting the antenna resonant frequency and expanding the working bandwidth; on the other hand, the introduction of the transverse branch increases the gap length between the horizontal branch of the L probe and the main radiation patch, thereby increasing the adjustable range of the gap length, which also improves the freedom of the antenna structure and is conducive to the miniaturization design of the antenna.

[0016] 3. Square parasitic patches are introduced at the four corners of the radiation layer. The introduction of traditional parasitic patches only considers the electromagnetic coupling with the main radiation patch, while the present invention also considers the interaction with the horizontal branch of the L probe. Specifically, electromagnetic coupling is generated between the parasitic patch and the main radiation patch and the vertical branch of the L probe, respectively. From the perspective of the equivalent circuit, it can be equivalent to the introduction of a new coupling capacitor, which interacts with the equivalent inductance of the vertical branch of the L-shaped probe to produce additional resonant frequencies, further expanding the working bandwidth of the patch antenna. In particular, when the antenna of the present invention is used as a phased array unit, the radiation pattern and beam pointing of the antenna can be adjusted by adjusting the size and position of the parasitic patch, thereby achieving wide-angle scanning.

[0017] 4. The first dielectric layer adopts a double-layer dielectric layer. The double-layer dielectric structure provides additional design flexibility compared to the single-layer dielectric. In addition, the lower layer of the double-layer dielectric layer in the present invention is made of PMI foam material. The material's own characteristics make its thickness adjustable in a wide range, while reducing the weight of the antenna; the upper layer of the double-layer dielectric layer is a high-hardness, low-loss TSM-DS3 dielectric substrate, which plays a role in protecting the antenna and avoids the installation of a conventional antenna cover.

[0018] 5. The feeding network of the present invention adopts a cascade connection method of a second-order Wilkinson power divider and a broadband 180° phase shifter, which expands the working bandwidth of the feeding network and improves the phase stability of the feeding network. The phase-stable structure consists of two wires with a length difference of λ / 2 transmission line, and two sets of spacing are loaded on the shorter transmission line λ / 2 open line and short line, forming an I-shaped structure, the length of the open line and the length of the short line are both λ / 8. In particular, the feed network isolation structure in the present invention adopts a combination of metal through holes and metal slots, with metal slots being provided in places with larger reserved spaces and metal through holes being provided in places with smaller reserved spaces, taking into account both design flexibility and stability of isolation characteristics. Furthermore, it ensures that the two feed probes in the antenna are fed in reverse with close to equal amplitude, so that the antenna maintains excellent radiation performance within the wide-band and large-angle range of the H-plane.

[0019] 6. The H-plane scanning angle of the antenna of the present invention can reach 0±60°, the operating frequency band covers 6.8~12.4GHz, the operating bandwidth reaches 58.3%, and it has the characteristics of low profile and stable structure. Compared with the traditional non-planar L-probe feeding structure, it has better structural strength, lower profile, easier processing, and is suitable for use as a conformal antenna array unit or a phased antenna array unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the antenna of the present invention; Figure 2 yes Figure 1 sectional view of Figure 3 yes Figure 1 The structural breakdown diagram of Figure 4 It is a top view of the structure of the broadband phase-stable feeding network; Figure 5 is the amplitude diagram of the two output ports of the broadband phase-stable feeding network; Figure 6 is the phase difference diagram of the two output ports of the broadband phase-stable feeding network; Figure 7 It is the antenna standing wave diagram corresponding to the antenna of the present invention.

[0021] Among them: 1. The first dielectric layer; 1.1. The upper substrate of the first dielectric layer; 1.2. The lower substrate of the first dielectric layer; 2. The second dielectric layer; 2.1. The substrate of the second dielectric layer; 2.2. The vertical branch of the feed probe; 3. The third dielectric layer; 3.1. The metal ground above the upper substrate of the third dielectric layer; 3.2. The upper substrate of the third dielectric layer; 3.3. The broadband phase-stable feeding network; 3.4. The lower substrate of the third dielectric layer; 3.5. The metal ground below the lower substrate of the third dielectric layer; 3.6. The metal through hole or metal groove; 3.7. The SMA connector; 3.8. The isolation resistor 4. The radiation layer; 4.1. The main radiation patch; 4.2. The horizontal branch of the feed probe; 4.3. The parasitic patch; 4.4. The lateral branch. DETAILED DESCRIPTION

[0022] The present invention will be described in detail below in conjunction with the accompanying drawings: like Figure 1-Figure 3As shown, the antenna structure of the present invention is a layered structure, including a first dielectric layer 1, a radiation layer 4, a second dielectric layer 2 and a third dielectric layer 3 from top to bottom.

[0023] The first dielectric layer 1 is a wide-angle matching layer, including a first dielectric layer upper substrate 1.1 and a first dielectric layer lower substrate 1.2. In the present invention, the first dielectric layer lower substrate 1.2 of the double-layer dielectric layer is made of PMI foam material, and the material's own characteristics make its thickness adjustable in a wide range, while reducing the weight of the antenna; the first dielectric layer upper substrate 1.1 of the double-layer dielectric layer is a high-hardness, low-loss TSM-DS3 dielectric substrate, which plays a role in protecting the antenna and avoids the installation of a conventional antenna cover.

[0024] The second dielectric layer 2 comprises a second dielectric layer substrate 2.1, in which vertical branches 2.2 of feeding probes are arranged, wherein the number of the vertical branches of the feeding probes is two.

[0025] The third dielectric layer 3 is composed of upper metal ground 3.1, upper substrate 3.2, lower substrate 3.4 and lower metal ground 3.5 from top to bottom. In addition, metal through holes or metal slots 3.6 are metallized vias that penetrate the third dielectric layer 3 and are respectively connected to the upper and lower metal grounds. The SMA connector 3.7 is the feed connector of the antenna and is located at the bottom of the third dielectric layer. The isolation resistor 3.8 is located in the feed network layer and is two in number. The broadband phase-stable feed network 3.3 is arranged between the upper substrate 3.2 and the lower substrate 3.4 of the third dielectric layer.

[0026] The radiation layer 4 is a metal patch, located between the first dielectric layer 1 and the second dielectric layer 2, and includes a main radiation patch 4.1, a probe horizontal branch and its loaded lateral branches 4.2, and a parasitic patch 4.3. The main radiation patch 4.1 is located at the center of the antenna, and is an improved square structure with four T-slots (stepped grooves) dug out on all sides. The number of the probe horizontal branch 4.2 and its loaded lateral branches 4.4 is four, and there is a certain gap between them and the main radiation patch 4.1; the parasitic patch 4.3 is square and located at the four corners of the antenna.

[0027] Figure 4 It is a top view of the structure of a broadband phase-stable feeding network, wherein output port 1 and output port 2 are located on the left and right layers and are electrically connected to the vertical branches of the feeding probes at the corresponding positions respectively.

[0028] Figure 5-Figure 6 This is the performance diagram of the broadband phase-stable feeding network of the present invention. Within the frequency band of 7.0~13.0GHz, the amplitudes of the two output ports are both greater than -3.4dB, and the amplitude difference is less than 0.2dB. At the same time, the phase difference between the two output ports fluctuates within the range of -180°±5°, and has the characteristics of good amplitude stability and phase stability within the broadband.

[0029] Figure 7 The antenna standing wave diagram corresponding to the present invention shows that the H-plane scanning angle can reach 60°, wherein the normal working frequency band (standing wave ratio ≤ 3) covers 6.8~13.5GHz, and the working bandwidth reaches 66.0%; in addition, the working frequency band in the entire scanning angle range covers 6.8~12.4GHz, and the working bandwidth reaches 58.3%.

[0030] At the same time, the corresponding antenna size of the present invention is 12mm×12mm×7.4mm, which meets the design requirements of antenna miniaturization and low profile, and is suitable as a unit to form a large-scale antenna array.

[0031] In summary, the present invention provides a low-profile, wide-bandwidth, large-scanning-angle patch antenna, which has the advantages of low profile, wide working bandwidth, large scanning angle, small size, and easy processing and integration, and has broad application prospects.

Claims

1. A low-profile, wide-band, large-scan-angle patch antenna, characterized in that: include: a first dielectric layer; A second dielectric layer, located below the first dielectric layer; The third dielectric layer; Located below the second dielectric layer; Radiative layer; Located between the first dielectric layer and the second dielectric layer; the radiation layer includes a main radiation patch, and a coupling notch is arranged at the edge of the main radiation patch; A feeding circuit is arranged in the third dielectric layer; Feeding probe; The feeding probe comprises a feeding probe vertical branch and a feeding probe horizontal branch; The horizontal branch of the feeding probe is coplanar with the main radiation patch of the radiation layer, and the vertical branch of the feeding probe is arranged in the second dielectric layer; one end of the vertical branch of the feeding probe is connected to one end of the horizontal branch of the feeding probe, and the other end of the vertical branch of the feeding probe is electrically connected to the output port of the feeding circuit; the front end of the horizontal branch of the feeding probe is located in the coupling slot of the main radiation patch to form a coupling gap, and the feeding probe feeds the main radiation patch through the coupling gap.

2. The low-profile, wide-band, large-scan-angle patch antenna according to claim 1, characterized in that: The coupling notch arranged at the edge of the main radiation patch is a stepped groove including a small width groove and a large width groove; the feeding probe also includes a lateral branch located near the end of the horizontal branch of the feeding probe, and the lateral branch is located in the large width groove.

3. The low-profile, wide-band, large-scan-angle patch antenna according to claim 2, characterized in that: The horizontal branches and transverse branches of the feeding probe are both rectangular strip structures.

4. The low-profile, wide-band, large-scan-angle patch antenna according to claim 1, characterized in that: The radiating layer also includes four parasitic patches.

5. The low-profile, wide-band, large-scan-angle patch antenna according to claim 4, characterized in that: The parasitic patches are square and are respectively located at the four corners of the antenna radiation layer.

6. The low-profile, wide-band, large-scan-angle patch antenna according to claim 1, characterized in that: The first dielectric layer includes a first dielectric layer upper substrate and a first dielectric layer lower substrate.

7. The low-profile, wide-band, large-scan-angle patch antenna according to claim 6, characterized in that: The lower substrate of the first dielectric layer is made of PMI foam material.

8. The low-profile, wide-band, large-scan-angle patch antenna according to claim 1, characterized in that: The third dielectric layer comprises, from top to bottom, an upper metal ground, a third dielectric layer upper substrate, a third dielectric layer lower substrate and a lower metal ground; the feed network is arranged between the third dielectric layer upper substrate and the third dielectric layer lower substrate.

9. The low-profile, wide-band, large-scan-angle patch antenna according to claim 1, characterized in that: The feeding network is composed of a second-order Wilkinson power divider and a broadband 180° phase shifter in cascade connection.

10. The low-profile, wide-band, large-sweep-angle patch antenna according to claim 9, characterized in that: The feeding network also includes a phase-stabilizing structure, which consists of two wires with a length difference of λ / 2 transmission line, and two sets of spacing are loaded on the shorter transmission line λ / 2 open line and short line, forming an I-shaped structure, the length of the open line and the length of the short line are both λ / 8.

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