A circularly polarized antenna array

Abstract

The present application belongs to the field of antenna technology and relates to a circularly polarized antenna array, comprising: four array-distributed antennas; the antenna comprises: a first radiating layer, a first dielectric layer, a second radiating layer, a second dielectric layer, and a floor layer stacked in sequence from top to bottom; the first radiating layer comprises: two spiral radiating arms spaced apart and centrally symmetrically distributed to form a circularly polarized spiral antenna; the second radiating layer is connected to the first radiating layer and has exactly the same structure; the first radiating layer and the second radiating layer are both connected to a feeding structure; the radiating arms are a first radiating arm and a second radiating arm; the starting ends of the first radiating arm and the second radiating arm are both located in the middle of the first dielectric layer, the terminal end of the first radiating arm is located in the middle of the antenna array, and the terminal end of the second radiating arm is located at a corner of the antenna array. The present application can simultaneously achieve ultra-wideband, high gain, circular polarization, and anti-interference, and has excellent axial ratio performance, making it easy to miniaturize.

Description

Technical Field

[0001] The present application relates to the field of antenna technology, and in particular to a circularly polarized antenna array. Background Art

[0002] The Global Navigation Satellite System (GNSS) is a satellite-based radio navigation system that uses artificial Earth satellites for navigation. In the military, satellite navigation systems assist aircraft, ships, and other equipment in precision strikes and provide accurate position and time information for reconnaissance and logistical support. In the civilian sector, satellite navigation systems are playing an increasingly important role in surveying and mapping, telecommunications, water conservancy, fisheries, transportation, forest fire prevention, and disaster reduction and relief.

[0003] GNSS receivers typically receive signals from multiple constellations, including the US GPS, Russia's GLONASS, Europe's Galileo, and China's BeiDou. This requires the receiving antenna to operate across multiple frequencies in the L-band (1150–1610 MHz). However, GNSS signals are typically very weak, so the receiving antenna must have high gain across the entire upper half of the spectrum and good circular polarization performance.

[0004] Currently, in an increasing number of application scenarios, GNSS antennas are installed on platforms with very limited space, such as small devices like drones and cars. In order to achieve both high gain and ultra-wideband design, antenna miniaturization has reached its theoretical limit. In addition, practical applications usually require GNSS antennas to be as low-cost and simple-structured as possible.

[0005] However, in some complex application scenarios, navigation systems are often subject to severe radio frequency interference. GNSS antenna arrays are shaped to provide an adaptive directional pattern, nulling the gain of interfering signals. This effectively suppresses radio frequency interference. This type of antenna is commonly referred to as a controlled radiating antenna. A typical controlled radiating antenna is 14 inches (35.6 cm) in size and can contain 5-8 antenna elements. The number of elements and aperture of the array significantly impact key performance factors such as nulling, phase coherence, gain, and coverage in interference environments.

[0006] However, the size of the above-mentioned mature controlled radiation antennas is still too large for platforms such as drones, and most of them can only cover a small part of the frequency points of GNSS signals, which cannot meet the requirements of application scenarios. Summary of the Invention

[0007] Based on this, it is necessary to provide a circularly polarized antenna array to address the above technical problems, which can simultaneously achieve ultra-wideband, high gain, circular polarization, anti-interference, good axial ratio performance, and easy miniaturization.

[0008] A circularly polarized antenna array, comprising: four array-distributed antennas;

[0009] The antenna comprises: a first radiation layer, a first dielectric layer, a second radiation layer, a second dielectric layer and a floor layer stacked in sequence from top to bottom;

[0010] The first radiation layer includes: two spaced-apart and centrally symmetrically distributed spiral radiation arms to form a circularly polarized spiral antenna;

[0011] The second radiation layer is connected to the first radiation layer and has the same structure;

[0012] The first radiation layer and the second radiation layer are both connected to the feeding structure.

[0013] In one embodiment, the radiating arm is a first radiating arm and a second radiating arm;

[0014] The starting ends of the first radiation arm and the second radiation arm are both located in the middle of the first dielectric layer, the terminal end of the first radiation arm is located in the middle of the antenna array, and the terminal end of the second radiation arm is located at a corner of the antenna array.

[0015] In one embodiment, the radiating arm is in a rectangular spiral shape to form a rectangular spiral antenna.

[0016] In one embodiment, the first radiation layer further comprises: an absorbing resistor;

[0017] One end of the absorbing resistor is connected to the terminal of the first radiation arm, and the other end is connected to a position on the second radiation arm adjacent to the terminal of the first radiation arm.

[0018] In one embodiment, the four antennas are distributed symmetrically around the center.

[0019] In one embodiment, the first dielectric layer includes: a first substrate and a second substrate;

[0020] A balun is provided between the first substrate and the second substrate;

[0021] The balun is connected to both the first radiation layer and the second radiation layer.

[0022] In one embodiment, the balun is a rectangular spiral structure.

[0023] In one embodiment, one end of the balun is connected to the starting ends of the first radiation arms on the first radiation layer and the second radiation layer, and the other end extends from a position corresponding to the starting end of the second radiation arm along the path of the second radiation arm to a position corresponding to the terminal end of the second radiation arm between the first substrate and the second substrate.

[0024] In one embodiment, the terminal end of the second radiating arm is a semicircular structure.

[0025] In one embodiment, the antenna further comprises: a coaxial line, the coaxial line comprising: an outer conductor, an inner conductor, and an isolator disposed between the outer conductor and the inner conductor;

[0026] The outer conductor is connected to a terminal of the second radiation arm on the second radiation layer, and the inner conductor is connected to the balun at a position corresponding to the terminal of the second radiation arm.

[0027] The circularly polarized antenna array can cover the entire L-band GNSS frequency band (1150-1600MHz), while achieving ultra-wideband, high gain, circular polarization, anti-interference, and excellent axial ratio performance, making it easy to miniaturize. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a three-dimensional schematic diagram of a circularly polarized antenna array in one embodiment;

[0029] Figure 2 is a side view of a circularly polarized antenna array according to an embodiment;

[0030] Figure 3 is a top view of a first radiating layer of a circularly polarized antenna array in one embodiment;

[0031] Figure 4 FIG1 is a top view of a balun of a circularly polarized antenna array according to an embodiment;

[0032] Figure 5 is a perspective view of a balun and a second radiating layer of a circularly polarized antenna array according to one embodiment;

[0033] Figure 6 is a schematic diagram of a floor layer of a circularly polarized antenna array according to an embodiment;

[0034] Figure 7 is a schematic diagram of a coaxial line of a circularly polarized antenna array in one embodiment;

[0035] Figure 8 is a detailed schematic diagram of a coaxial line of a circularly polarized antenna array in one embodiment;

[0036] Figure 9 is a graph of active reflection coefficient of an antenna array in one embodiment;

[0037] Figure 10 is a graph showing the resistance (real part of impedance) of an antenna array in an operating frequency band in one embodiment;

[0038] Figure 11is a graph of the reactance (imaginary impedance) of the antenna array in an operating frequency band in one embodiment;

[0039] Figure 12 : is the gain pattern of the antenna array at the GPS L1 C / A1575.42 GHz frequency in one embodiment;

[0040] Figure 13 : is the gain pattern of the antenna array at the GPS L2 C1227.6GHz frequency in one embodiment;

[0041] Figure 14 : is the gain pattern of the antenna array at BDS B2a 1176.45 GHz frequency in one embodiment;

[0042] Figure 15 : is the gain pattern of the antenna array at the BDS B1I 1561.098 GHz frequency in one embodiment;

[0043] Figure 16 : is the gain pattern of the antenna array at BDS B3 1268.52 GHz frequency in one embodiment;

[0044] Figure 17 1 is an axial ratio diagram of the antenna array at the GPS L1 C / A1575.42GHz frequency point in one embodiment;

[0045] Figure 18 2 is an axial ratio diagram of the antenna array at the GPS L2 C1227.6GHz frequency point in one embodiment;

[0046] Figure 19 1 is an axial ratio diagram of the antenna array at the BDS B2a 1176.45 GHz frequency point in one embodiment;

[0047] Figure 20 1 is an axial ratio diagram of the antenna array at the BDS B1I 1561.098 GHz frequency point in one embodiment;

[0048] Figure 21 FIG. 1 is an axial ratio diagram of the antenna array at the BDS B3 1268.52 GHz frequency point in one embodiment.

[0049] Reference numerals:

[0050] First radiation layer 1, first radiation arm 11, second radiation arm 12, absorbing resistor 13, connecting hole 14, metal via 15;

[0051] First dielectric layer 2, first substrate 21, second substrate 22;

[0052] A second dielectric layer 3;

[0053] Floor layer 4, feeding hole 41;

[0054] Barron 5;

[0055] Coaxial cable 6. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely for explaining this application and are not intended to limit this application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in this application without creative work are within the scope of protection of this application.

[0057] It should be noted that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0058] In addition, the terms "first," "second," and so on, used in this application are for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this application, "multiple groups" means at least two groups, such as two groups, three groups, and so on, unless otherwise specifically defined.

[0059] In this application, unless otherwise specified or limited, the terms "connect," "fix," etc. should be understood in a broad sense. For example, "fix" can mean a fixed connection, a detachable connection, or an integral connection; it can mean a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean internal communication between two elements or an interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0060] In addition, the technical solutions between the various embodiments of the present application can be combined with each other, but it must be based on the fact that ordinary technicians in this field can implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0061] This application provides a circularly polarized antenna array, such as Figures 1 to 8As shown, in one embodiment, it includes: four antennas, and the four antennas are distributed in a centrally symmetrical 2×2 array, that is, the four antennas are rotated 90° in sequence with the antenna array as the center to reduce the mutual coupling between the antennas and effectively improve the axial ratio of the antenna array.

[0062] The antenna includes: a first radiation layer, a first dielectric layer, a second radiation layer, a second dielectric layer, a floor layer, a balun and a coaxial line, wherein the first radiation layer, the first dielectric layer, the second radiation layer, the second dielectric layer and the floor layer are stacked in sequence from top to bottom.

[0063] The first radiation layer includes two spiral radiation arms and an absorbing resistor.

[0064] The two radiating arms are spaced apart and symmetrically distributed in the center to form a circularly polarized helical antenna; the radiating arms are a first radiating arm and a second radiating arm, the starting ends of the first radiating arm and the second radiating arm are both located in the middle of the upper surface of the first dielectric layer, the terminal end of the first radiating arm is located in the middle of the antenna array, and the terminal end of the second radiating arm is located at a corner of the antenna array; wherein the starting end is as Figure 3 As shown in the A end, the terminal is as Figure 3 End B shown.

[0065] Preferably, the radiating arm is in a rectangular spiral shape, forming a planar rectangular spiral antenna, so as to improve space utilization and further achieve a compact and miniaturized structure.

[0066] Further preferably, the terminal end of the second radiating arm is a semicircular structure to reduce end reflection, and is provided with a connecting hole to be connected to the coaxial line.

[0067] One end of the absorbing resistor is connected to the terminal of the first radiating arm, and the other end is connected to a position on the second radiating arm adjacent to the terminal of the first radiating arm to absorb the transmitted wave at the end of the planar spiral antenna and further improve the standing wave ratio of the antenna in the low frequency band.

[0068] The first dielectric layer is a bearing layer, and includes: a first substrate and a second substrate; the first substrate and the second substrate are completely identical, including: material, shape, size, and thickness.

[0069] The structure of the second radiating layer is identical to that of the first radiating layer, and the second radiating layer is connected to the first radiating layer. Specifically, a plurality of through holes perpendicular to the first dielectric layer are evenly provided on the first dielectric layer at positions corresponding to both sides of the length direction of each radiating arm, so that metal vias are provided in the through holes, and the second radiating layer is electrically connected to the first radiating layer through the metal vias, thereby ensuring that the electric potential in each direction is equal.

[0070] The second dielectric layer is a bearing layer, which not only supports the second radiation layer and coaxial line structures, but also enables miniaturized design. The thickness of the second dielectric layer is greater than that of the first dielectric layer, and the thickness of the second dielectric layer is one-quarter of the effective wavelength of the working center frequency to achieve single-sided radiation of the antenna array.

[0071] The floor layer is a metal floor with a feeding hole provided on the metal floor so that the coaxial line can pass through the feeding hole and then be connected to the antenna.

[0072] The balun is arranged between the first substrate and the second substrate, and is connected to the first radiating layer and the second radiating layer at the same time to form spatial symmetry, and feeds the two antennas at the same time, so as to balance the feeding, reduce parasitic current, and further improve bandwidth and gain.

[0073] Preferably, the balun is a strip balun, specifically a rectangular spiral structure, which increases the transmission distance, can gradually achieve the transformation from current imbalance to balance, and effectively improve impedance matching, thereby further expanding the working bandwidth of the antenna array.

[0074] Further preferably, one end of the balun is connected to the first radiating layer and the starting end of the first radiating arm on the second radiating layer at the same time (specifically, through a metal via perpendicular to the first dielectric layer), and the connection point of this end serves as a circular pad. The circular pad and the two planar spiral antennas generate capacitance, which can offset the inductance of the coaxial line transmission and improve the conjugate matching. The other end starts from the position corresponding to the starting end of the second radiating arm and extends along the path of the second radiating arm to the position corresponding to the terminal end of the second radiating arm between the first substrate and the second substrate, and is connected to the inner conductor of the coaxial line to feed the planar rectangular spiral antenna.

[0075] More preferably, the balun extends along a path corresponding to the center line of the second radiation arm to effectively improve impedance matching, thereby further widening the operating bandwidth of the array.

[0076] The coaxial line includes an outer conductor, an inner conductor, and an isolator. One end of the coaxial line is connected to the external input interface (50Ω) below the floor layer. The other end passes through the floor layer and the second dielectric layer. The outer conductor is connected to the terminal end of the second radiating arm on the second radiating layer. The inner conductor is connected to a balun at the position corresponding to the terminal end of the second radiating arm. Through the balun, it is simultaneously connected to the starting end of the first radiating arm on the first and second radiating layers. The isolator is located between the outer and inner conductors and is made of insulating material to achieve isolation between the outer and inner conductors.

[0077] In this embodiment, the balun and the coaxial line together form a feeding structure, and each antenna is fed separately.

[0078] It should be noted that the first dielectric layer, the second dielectric layer and the floor layer of the four antennas can be integrally formed.

[0079] The circularly polarized antenna array can cover the entire L-band GNSS frequency band (1150-1600MHz), while achieving ultra-wideband, high gain, circular polarization, anti-interference, and excellent axial ratio performance, making it easy to miniaturize.

[0080] Specifically:

[0081] 1. The GNSS ultra-wideband circularly polarized antenna array of this application greatly reduces the characteristic impedance of the antenna unit through the upper and lower parallel planar spiral antennas, while also reducing the difficulty of feed matching, effectively expanding the bandwidth of the array.

[0082] 2. The "sandwich" structure of the bent stripline balun rationally utilizes the space between the upper and lower planar spiral antennas, feeds the antennas in parallel at the same time, and is symmetrical. In addition, the bent structure can achieve unbalanced-balanced feeding in a limited space, effectively further expanding the bandwidth of the array.

[0083] 3. Sequentially arranged planar spiral antennas can improve the isolation between array elements, thereby achieving miniaturization within a limited space while improving the axial ratio of the array.

[0084] 4. The use of dielectric plates with high dielectric constants can not only effectively reduce the size of the array, but also provide support for the antenna units, thereby improving the structural stability of the array.

[0085] In a specific embodiment, the dielectric constant of the first dielectric layer is 10.7, the dielectric constant of the second dielectric layer is 4, and the size of the entire antenna is 89 mm × 89 mm, which is only 0.34λ. l ×0.34λ l , with the advantage of miniaturization, it is ideally suited for space-constrained platforms such as drones and handheld receivers. The upper and lower planar spiral antennas of the first and second radiating layers form a parallel structure from an equivalent circuit perspective, reducing the characteristic impedance of the planar spiral antennas from 140Ω to 70Ω, closer to the 50Ω input impedance. This greatly simplifies impedance matching and effectively expands the antenna's operating bandwidth. The coaxial line impedance is 60Ω, which is between the 50Ω input resistance and the 70Ω characteristic impedance of the parallel planar spiral antennas. This improves impedance matching and enhances antenna array performance.

[0086] The above antenna array is simulated and verified, and the results are as follows Figures 9 to 21 shown.

[0087] like Figure 9 As shown in Figure 2, the antenna array achieves an impedance bandwidth of 1.15-1.65 GHz, indicating that the antenna array has good transmission performance in this frequency band.

[0088] like Figure 10 As shown in the figure, the resistance of the antenna array in the working frequency band is maintained at about 50Ω, indicating that the antenna array has good output.

[0089] like Figure 11 As shown in Figure 1, the reactance of the antenna array in the 1.15-1.6 GHz frequency band is maintained at around 0 Ω, indicating that the antenna array has good matching.

[0090] like Figure 12 As shown, the gain of the antenna array in the normal 0° direction is greater than 0dBi.

[0091] like Figure 13 As shown, the gain of the antenna array in the normal 0° direction is greater than 0dBi.

[0092] like Figure 14 As shown, the gain of the antenna array in the normal 0° direction is greater than 0dBi.

[0093] like Figure 15 As shown, the gain of the antenna array in the normal 0° direction is greater than 0dBi.

[0094] like Figure 16 As shown, the gain of the antenna array in the normal 0° direction is greater than 0dBi.

[0095] like Figure 17 As shown, the axial ratio of the antenna array at -80° to 80° is less than 2dB.

[0096] like Figure 18 As shown, the axial ratio of the antenna array at -80° to 80° is less than 2dB.

[0097] like Figure 19 As shown, the axial ratio of the antenna array at -80° to 80° is less than 2dB.

[0098] like Figure 20 As shown, the axial ratio of the antenna array at -80° to 80° is less than 5dB.

[0099] like Figure 21 As shown, the axial ratio of the antenna array at -80° to 80° is less than 6dB.

[0100] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

[0101] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0102] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. A circularly polarized antenna array, characterized in that: include: Four array-distributed antennas; The antenna comprises: a first radiation layer, a first dielectric layer, a second radiation layer, a second dielectric layer and a floor layer stacked in sequence from top to bottom; The first radiating layer includes: two spaced-apart and centrally symmetrically distributed spiral radiating arms to form a circularly polarized helical antenna; the radiating arms are a first radiating arm and a second radiating arm; the starting ends of the first radiating arm and the second radiating arm are both located in the middle of the first dielectric layer, the terminal end of the first radiating arm is located in the middle of the antenna array, and the terminal end of the second radiating arm is located at a corner of the antenna array; The second radiation layer is connected to the first radiation layer and has the same structure; The first radiating layer and the second radiating layer are both connected to the feeding structure; the first dielectric layer includes: a first substrate and a second substrate; a balun is provided between the first substrate and the second substrate; the balun is simultaneously connected to the first radiating layer and the second radiating layer; the balun is a rectangular spiral structure; one end of the balun is simultaneously connected to the starting ends of the first radiating arms on the first radiating layer and the second radiating layer, and the other end extends from a position corresponding to the starting end of the second radiating arm along the path of the second radiating arm to a position corresponding to the terminal end of the second radiating arm between the first substrate and the second substrate.

2. The circularly polarized antenna array according to claim 1, wherein: The radiating arm is in a rectangular spiral shape to form a rectangular spiral antenna.

3. A circularly polarized antenna array according to claim 1 or 2, characterized in that: The first radiation layer further includes: an absorbing resistor; One end of the absorbing resistor is connected to the terminal of the first radiation arm, and the other end is connected to a position on the second radiation arm adjacent to the terminal of the first radiation arm.

4. A circularly polarized antenna array according to claim 1 or 2, characterized in that: The four antennas are distributed symmetrically around the center.

5. A circularly polarized antenna array according to claim 1 or 2, characterized in that: The terminal end of the second radiation arm is a semicircular structure.

6. A circularly polarized antenna array according to claim 1 or 2, characterized in that: The antenna further comprises: a coaxial line, the coaxial line comprising: an outer conductor, an inner conductor, and an isolator provided between the outer conductor and the inner conductor; The outer conductor is connected to a terminal of the second radiation arm on the second radiation layer, and the inner conductor is connected to the balun at a position corresponding to the terminal of the second radiation arm.

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