A fed high-orthogonality microstrip antenna

Abstract

The present invention relates to the field of radar and communications technology, and in particular to a radar in which an antenna and radio frequency receiving and transmitting links are integrated on the same circuit board. This invention is particularly suitable for scenarios where the circuit board requires high integration, small size, and low cost, and signal interference between the receiving and transmitting ends is relatively prominent. Specifically, it relates to a high-orthogonality microstrip antenna with feeding. The present invention implements a special feeding design for a single antenna patch-dual feeding scheme, allowing the equivalent feeding points of the two channels to be easily adjusted, correcting the problem of decreased orthogonality caused by the asymmetry of the antenna patch's operating environment to ensure the antenna patch's isolation level. The coupled feeding method of the present invention has a compact layout, a flexible range of adjustable feeding positions, and significantly improved isolation after optimization.

Description

Technical Field

[0001] The present invention belongs to the field of radar and communication technology, and in particular relates to a radar in which an antenna and radio frequency receiving and transmitting links are integrated on the same circuit board. The present invention is particularly suitable for scenarios where high integration, small size, and low-cost design requirements are placed on the circuit board and where signal interference between the receiving and transmitting ends is relatively prominent. The present invention specifically relates to a fed high-orthogonality microstrip antenna. Background Art

[0002] Because radar systems are passive in their detection, their feedback signals are extremely weak compared to active communication devices that actively return signals. Therefore, radar systems typically require higher adjustable transmit power and higher receive sensitivity to capture weak signals. This creates a higher requirement for interference isolation between high-power transmit links and high-sensitivity receive links, becoming a bottleneck influencing the overall performance of radar systems.

[0003] In the field of civilian consumer radar, due to strict space and cost constraints, highly integrated and miniaturized radar designs have become the mainstream. Furthermore, radars use a single antenna patch for both transmit and receive channels to minimize radar size. Therefore, improving the anti-interference capability between transmit and receive channels within a single antenna patch design has become a key issue in radar system design.

[0004] When receiving and transmitting channels share a single antenna patch, the key to improving isolation is to ensure orthogonality between the receive and transmit excitations. Specifically, the feed point for one channel should be located at the point where the electric field distribution is weakest when the other channel feeds the antenna patch. For example, with commonly used microstrip patch antennas, the typical approach is to orthogonally position the feed points for both the receive and transmit channels, with the geometric center of the antenna patch as the coordinate origin, at 90°.

[0005] However, in actual engineering, due to layout restrictions, the antenna patch may be placed at the edge of the radar module, or there may be metal components around the antenna patch, which will destroy the symmetry of the antenna patch's working environment and change the electric field distribution excited by the transmitting channel. The antenna transmission line also has a certain radiation capability. In the actual layout, as the length of the transmission line increases, its own radiation becomes non-negligible, which also destroys the originally designed electric field distribution. That is, the electric field strength at the feeding position of the receiving channel is no longer weak, resulting in increased interference and decreased performance. Summary of the Invention

[0006] In view of this, the present invention proposes a fed high-orthogonality microstrip antenna, which implements a special feeding design for the single antenna patch-dual feeding scheme, so that the equivalent feeding points of the two channels can be easily adjusted, correcting the problem of decreased orthogonality caused by the asymmetry of the antenna patch working environment. Through the coupled feeding design, the transmission line and the antenna are not directly physically connected, reducing the impact of the transmission line radiation on the antenna radiation electric field distribution, thereby ensuring the isolation level of the antenna patch.

[0007] In order to achieve the above technical objectives, the specific technical solutions adopted by the present invention are:

[0008] A fed high-orthogonality microstrip antenna, comprising:

[0009] A substrate, wherein the two opposite sides are respectively a radiation surface and a ground surface;

[0010] The radiation patch is a regular polygon or a circle, and is laid on the radiation surface; the regular polygon includes two sides perpendicular to each other, forming a transmitting feed side and a receiving feed side respectively; the circle includes two tangents perpendicular to each other, forming a transmitting feed side and a receiving feed side respectively;

[0011] A reference ground is provided on the ground plane and is used for the antenna to form a resonant circuit of the radiation patch;

[0012] a transmitting feed line, the feeding end of which is grounded, laid on the radiation surface, parallel to and spaced from the transmitting feed edge, and used to cause the radiation patch to emit electromagnetic waves based on the capacitive effect with the radiation patch and the resonant circuit when an electromagnetic excitation signal is connected;

[0013] A receiving feeder line, with a feeding end grounded, is laid on the radiation surface, parallel to and spaced apart from the receiving feeder edge, and is used to receive electromagnetic waves transmitted to the radiation patch based on the capacitive effect with the radiation patch and the resonant circuit.

[0014] Furthermore, the feeding end of the transmitting feeder is electrically connected to the reference ground; and the feeding end of the receiving feeder is electrically connected to the reference ground.

[0015] Furthermore, the initial feeding end of the transmitting feed line is electrically connected to the transmitting end signal transmission line; the microstrip antenna also includes a transmitting coupling patch; the transmitting coupling patch is laid on the radiating surface, electrically connected to the reference ground, and is located at the end of the transmitting feed line and the transmitting end signal transmission line away from the radiating patch, and is used to isolate the electromagnetic radiation of the transmitting feed line away from the end of the radiating patch, or to isolate the electromagnetic radiation of the transmitting end signal transmission line.

[0016] Furthermore, a feeding end of the transmitting feed line is electrically connected to the transmitting coupling patch and / or the reference ground.

[0017] Furthermore, the initial feeding end of the receiving feeder line is electrically connected to the receiving end signal transmission line; the microstrip antenna also includes a receiving coupling patch; the receiving coupling patch is laid on the radiating surface, electrically connected to the reference ground, and is located at the end of the receiving feeder line and the receiving end signal transmission line away from the radiating patch, and is used to isolate the electromagnetic radiation of the receiving feeder line away from the end of the radiating patch, or to isolate the electromagnetic radiation of the receiving end signal transmission line.

[0018] Furthermore, a feeding end of the receiving feeder line is electrically connected to the receiving coupling patch and / or the reference ground.

[0019] Furthermore, the transmit coupling patch and / or the receive coupling patch are electrically connected to the reference ground based on a plurality of through holes passing through the substrate.

[0020] Furthermore, the distance between the transmitting feed line and the transmitting feed edge is 0.1-0.25 mm; the distance between the receiving feed line and the receiving feed edge is 0.1-0.25 mm.

[0021] Furthermore, the distance between the transmitting coupling patch and the transmitting feed line is 0.1-0.25 mm; the distance between the receiving coupling patch and the receiving feed line is 0.1-0.25 mm.

[0022] Furthermore, the lengths of the transmitting feeder and the receiving feeder are greater than one-quarter of the radio waves transmitted by the microstrip antenna; and the lengths of the receiving feeder and the receiving feeder are greater than one-quarter of the radio waves received by the microstrip antenna.

[0023] By adopting the above technical solution, the present invention can also bring the following beneficial effects:

[0024] The coupled feeding method of the present invention has a compact layout, a flexible range of adjustable feeding positions, and significantly improved isolation after optimization. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 The radiation surface layout diagram of the antenna environment is completely symmetrical;

[0027] Figure 2 The electric field distribution diagram of the radiation surface of the antenna environment is completely symmetrical;

[0028] Figure 3 This is the radiation surface layout diagram of the antenna environment that is not completely symmetrical;

[0029] Figure 4 This is the electric field distribution diagram of the radiation surface of the antenna environment that is not completely symmetrical;

[0030] Figure 5 This is a comparison chart of the isolation between completely symmetrical and asymmetrical antenna environments;

[0031] Figure 6 This is a radiation surface layout diagram of a fed high-orthogonality microstrip antenna in a specific embodiment of the present invention;

[0032] Figure 7 This is a diagram showing the electric field distribution of the radiation surface of a fed high-orthogonality microstrip antenna in a specific embodiment of the present invention;

[0033] Figure 8 This is a comparison diagram of the isolation between a fed high-orthogonality microstrip antenna and an antenna environment that is not completely symmetrical in a specific embodiment of the present invention;

[0034] Among them: 1. Radiating patch; 2. Transmitting feed line; 3. Receiving feed line; 4. Transmitting end signal transmission line; 5. Receiving end signal transmission line; 6. Transmitting coupling patch; 7. Receiving coupling patch. DETAILED DESCRIPTION

[0035] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0036] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0037] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present invention, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement an apparatus and / or practice a method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this apparatus and / or practice this method.

[0038] It should also be noted that the illustrations provided in the following embodiments are merely schematic illustrations of the basic concept of the present invention. The illustrations only show components related to the present invention and are not drawn according to the number, shape, and size of components in actual implementation. In actual implementation, the type, quantity, and proportion of each component may be changed arbitrarily, and the component layout may also be more complex.

[0039] Additionally, in the following description, specific details are provided to provide a thorough understanding of the examples. However, one skilled in the art will appreciate that the aspects described can be practiced without these specific details.

[0040] The following first analyzes the performance degradation caused by the asymmetric working environment of the antenna, which is integrated with the RF receiving and transmitting links on the same circuit board and has high integration, small size and low cost design requirements.

[0041] like Figure 1 、 2 As shown in the figure, when the antenna environment is completely symmetrical, the antenna electric field distribution is symmetrical, and the receiving end feeding point is at the zero point of the transmitting end radiation electric field; on the contrary, Figure 3 、 4 As shown in the figure, when the antenna environment is affected by factors such as the introduction of a feeder trace with a non-negligible length, the antenna being close to the board edge, or metal being close, the symmetry is destroyed and the isolation is deteriorated (the isolation comparison results are shown in Figure 5 shown).

[0042] The reason for the above-mentioned isolation degradation is that the microstrip line (transmitting and receiving feeder line 3) of considerable length itself generates radiation and becomes part of the antenna, thus destroying its symmetry.

[0043] Secondly, the following situations will also lead to worsening isolation:

[0044] 1. When the antenna is close to the edge of the board, the nearby electric field environment changes from the PCB board to a mixture of air and PCB board, the wavelength of the local electromagnetic field becomes longer, and its symmetry is destroyed;

[0045] 2. When the antenna is close to the metal, contrary to being close to the edge of the board, the wavelength of the electromagnetic field around the metal becomes shorter, destroying its symmetry.

[0046] 3. The antenna transmission line also has a certain radiation capability. In the actual layout, as the length of the transmission line increases, its own radiation becomes non-negligible, which also destroys the originally designed electric field distribution and its symmetry.

[0047] In order to solve the above problems, in one embodiment of the present invention, a high-orthogonality microstrip antenna is provided.

[0048] include:

[0049] A substrate, wherein the two opposite sides are respectively a radiation surface and a ground surface;

[0050] The radiation patch 1 is a regular polygon or a circle and is laid on the radiation surface; the regular polygon includes two mutually perpendicular sides, which respectively form a transmitting feed side and a receiving feed side; the circle includes two mutually perpendicular tangents, which respectively form a transmitting feed side and a receiving feed side;

[0051] A reference ground is provided on the ground plane and is used for the antenna to form a resonant circuit of the radiation patch 1;

[0052] The transmitting feed line 2 has a grounded feed end and is laid on the radiating surface, parallel to and spaced from the transmitting feed edge. When the electromagnetic excitation signal is connected, it is used to achieve coupling transmission of electromagnetic wave signals based on the capacitive effect with the radiating patch 1 and a resonant circuit to enable the radiating patch 1 to emit electromagnetic waves;

[0053] The receiving feed line 3, with the feeding end grounded, is laid on the radiating surface, parallel to the receiving feed edge and spaced apart, and is used to realize the coupled transmission of electromagnetic wave signals based on the capacitive effect with the radiating patch 1 and the resonant circuit receives the electromagnetic waves transmitted to the radiating patch 1.

[0054] The substrate of this embodiment is a PCB board or other material that can be etched with a metal patch, which is not specifically limited in this embodiment. The radiating patch 1 of this embodiment is a metal patch used for making a microstrip antenna, and adopts an equilateral design, that is, a square, a regular octagon, a circle, etc. structure, which is not specifically limited in this embodiment.

[0055] In some embodiments, the feeding end of the transmitting feeder 2 is electrically connected to the reference ground; and the feeding end of the receiving feeder 3 is electrically connected to the reference ground.

[0056] In some embodiments, the initial feed end of the transmitting feed line 2 is electrically connected to the transmitting signal transmission line 4. The microstrip antenna also includes a transmitting coupling patch 6. This transmitting coupling patch 6 is laid on the radiating surface, electrically connected to the reference ground, and located at the end of the transmitting feed line 2 and the transmitting signal transmission line 4 away from the radiating patch 1. It is used to isolate electromagnetic radiation from the end of the transmitting feed line 2 away from the radiating patch 1, or to isolate electromagnetic radiation from the transmitting signal transmission line 4. In this embodiment, the transmitting signal transmission line 4 should avoid turning points such as the antenna's top corner.

[0057] The feeding end of the transmitting feeding line 2 is electrically connected to the transmitting coupling patch 6 and / or the reference ground.

[0058] The initial feed end of the receiving feed line 3 is electrically connected to the receiving signal transmission line 5. The microstrip antenna also includes a receiving coupling patch 7. This receiving coupling patch 7 is laid on the radiating surface and electrically connected to the reference ground. It is located at the end of the receiving feed line 3 and the receiving signal transmission line 5 that is away from the radiating patch 1. It is used to isolate electromagnetic radiation from the end of the receiving feed line 3 away from the radiating patch 1, or from electromagnetic radiation from the receiving signal transmission line 5. In this embodiment, the receiving signal transmission line 5 should avoid turning points such as the antenna's top corner.

[0059] The feeding end of the receiving feeding line 3 is electrically connected to the receiving coupling patch 7 and / or the reference ground.

[0060] The transmit coupling patch 6 and / or the receive coupling patch 7 are electrically connected to the reference ground based on a plurality of through holes passing through the substrate.

[0061] In this embodiment, the distance between transmit feeder line 2 and the transmit feed edge is 0.1-0.25 mm; the distance between receive feeder line 3 and the receive feed edge is 0.1-0.25 mm. The distance between transmit coupling patch 6 and transmit feeder line 2 is 0.1-0.25 mm; the distance between receive coupling patch 7 and receive feeder line 3 is 0.1-0.25 mm. The length of transmit feeder line 2 and receive feeder line 3 is greater than one-quarter of the radio waves transmitted by the microstrip antenna; the length of receive feeder line 3 and receive feeder line 3 is greater than one-quarter of the radio waves received by the microstrip antenna.

[0062] In this embodiment, the transmission feeder 2 and the transmission feeder and the antenna radiation edge can be regarded as a capacitor element, and the capacitance value formula is as follows:

[0063]

[0064] Where ε is the dielectric constant of the transmission medium, l is the length of the coupling section, d is the distance between the coupling section and the antenna radiation edge, and a is the width of the coupling section stripline.

[0065] At the same time, the capacitor can be regarded as a high-pass filter, and its cut-off frequency formula is as follows:

[0066]

[0067] Therefore, to ensure that the signal at the radar operating frequency f can be transmitted to the antenna through the coupling section, the above two formulas show that the capacitance C must be greater than a specific value, that is, the length l of the transmitting feed line 2 and the transmission feed line must be greater than a specific value, and the spacing d must be sufficiently small. In actual engineering experience, the length of the transmitting feed line 2 and the transmission feed line should be greater than one-quarter of the wavelength of the microstrip antenna's RF operating frequency. Given the limitations of machining accuracy, the spacing from the antenna's radiating edge should be less than 0.25mm, approximately 0.1-0.25mm, and recommended to be around 0.15mm.

[0068] The coupled feed ends of the transmitting feed line 2 and the transmission feed line of this embodiment should be grounded, and can be connected to the receiving coupling patch 7 and the transmitting coupling patch 6, or can be connected to the bottom reference ground through a via;

[0069] like Figure 6 As shown, the receiving coupling patch 7 and the transmitting coupling patch 6 of this embodiment fully wrap the transmitting feed line 2 and the end of the transmission feed line away from the radiation patch 1, and try to fully wrap the transmitting end signal transmission line 4 and the receiving end signal transmission line 5. The spacing is minimized as much as possible. In view of the limitation of processing accuracy, it is about 0.1-0.25mm, and it is recommended to be around 0.15mm.

[0070] The above embodiments are general design requirements. The following describes the specific design requirements for specific cases. Figure 6 The antenna isolation of the application shown in the figure is poor, mainly because the antenna is placed at the edge of the board and the long feed transmission line participates in the antenna radiation, which destroys the orthogonality of the electric field at the two ports. By adjusting the length of the transmitting feed line 2 and the transmission feed line, as well as the relative position of the transmitting feed line 2 and the transmission feed line to the radiation patch 1, the electric field distribution at the two ports is made orthogonal again, thereby optimizing the isolation between the two antenna ports. Figure 7 As shown in the figure, when the transmitting end excites the electromagnetic wave signal, the intensity zero point of the electromagnetic wave is linearly distributed, and the equivalent feeding point coupled by the receiving end is near the zero point (such as Figure 7 shown).

[0071] like Figure 8 As shown, the antenna isolation of this embodiment is improved by about 20 dB compared to the asymmetric design without any treatment, and the interference is reduced to one percent of the original.

[0072] 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 changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A high-orthogonality microstrip antenna, characterized in that: include: A substrate, wherein the two opposite sides are respectively a radiation surface and a ground surface; The radiation patch is a regular polygon or a circle, and is laid on the radiation surface; the regular polygon includes two sides perpendicular to each other, forming a transmitting feed side and a receiving feed side respectively; the circle includes two tangents perpendicular to each other, forming a transmitting feed side and a receiving feed side respectively; A reference ground is provided on the ground plane and is used for the antenna to form a resonant circuit of the radiation patch; A transmitting feed line, with a feeding end grounded, is laid on the radiating surface, parallel to and spaced from the transmitting feed edge, and is used to cause the radiating patch to emit electromagnetic waves based on the capacitive effect with the radiating patch and the resonant circuit when an electromagnetic excitation signal is connected; the feeding initial end of the transmitting feed line is electrically connected to a transmitting end signal transmission line; the microstrip antenna further comprises a transmitting coupling patch; the transmitting coupling patch is laid on the radiating surface, electrically connected to the reference ground, and is located at one end of the transmitting feed line and the transmitting end signal transmission line away from the radiating patch, and is used to isolate the electromagnetic radiation of the transmitting feed line away from the end of the radiating patch, or to isolate the electromagnetic radiation of the transmitting end signal transmission line; A receiving feeder line, with its feeding end grounded, is laid on the radiating surface, parallel to and spaced apart from the receiving feed edge, and is used to receive electromagnetic waves transmitted to the radiating patch based on the capacitive effect with the radiating patch and the resonant circuit; the feeding initial end of the receiving feeder line is electrically connected to the receiving end signal transmission line; the microstrip antenna also includes a receiving coupling patch; the receiving coupling patch is laid on the radiating surface, electrically connected to the reference ground, and is located at one end of the receiving feeder line and the receiving end signal transmission line away from the radiating patch, and is used to isolate the electromagnetic radiation of the receiving feeder line away from the end of the radiating patch, or to isolate the electromagnetic radiation of the receiving end signal transmission line.

2. The feed high orthogonality microstrip antenna according to claim 1, characterized in that: The feeding end of the transmitting feeder is electrically connected to the reference ground; the feeding end of the receiving feeder is electrically connected to the reference ground.

3. The feed high orthogonality microstrip antenna according to claim 1, characterized in that: The feeding end of the transmitting feed line is electrically connected to the transmitting coupling patch and / or the reference ground.

4. The feed high orthogonality microstrip antenna according to claim 1, characterized in that: The feeding end of the receiving feeding line is electrically connected to the receiving coupling patch and / or the reference ground.

5. The feed high orthogonality microstrip antenna according to claim 1, characterized in that: The transmit coupling patch and / or the receive coupling patch are electrically connected to the reference ground based on a plurality of through holes passing through the substrate.

6. The feed high orthogonality microstrip antenna according to claim 1, characterized in that: The distance between the transmitting feed line and the transmitting feed edge is 0.1-0.25 mm; the distance between the receiving feed line and the receiving feed edge is 0.1-0.25 mm.

7. The feed high orthogonality microstrip antenna according to claim 1, characterized in that: The distance between the transmitting coupling patch and the transmitting feed line is 0.1-0.25 mm; the distance between the receiving coupling patch and the receiving feed line is 0.1-0.25 mm.

8. The feed high orthogonality microstrip antenna according to claim 1, characterized in that: The lengths of the transmitting feed line and the receiving feed line are greater than one quarter of the radio waves transmitted by the microstrip antenna; the lengths of the receiving feed line and the receiving feed line are greater than one quarter of the radio waves received by the microstrip antenna.

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