Circularly polarized wide-beam antenna of S frequency band and Ku frequency band

Abstract

The utility model discloses an S-band and Ku-band circularly polarized wide-beam antenna, which comprises a conical metal base, an S-band feed network and cavity, a metal support column, an S-band conical logarithmic helical antenna, a Ku-band conical logarithmic helical antenna, a Ku-band bottom plate, a Ku-band slot balun, an antenna housing and two feed coaxial cables, the two feed coaxial cables both adopt semi-flexible cables with insulating sheaths, and comprise an S-band antenna feed cable and a Ku-band antenna feed cable. According to the scheme, through reasonable antenna type selection and layout, the circularly polarized signal receiving and transmitting functions of the S frequency band and the Ku frequency band are realized, the weight of the antenna is reduced, and the requirements of practical application are met.

Description

Technical Field

[0001] The utility model relates to the technical field of antennas, and in particular to a circularly polarized wide-beam antenna for S-band and Ku-band frequencies. Background Art

[0002] Today, communication technology is evolving at a rapid pace. The advent of 5G, and even the future 6G communications era, is driving comprehensive improvements in communication capacity, transmission speed, and coverage. Satellite communication systems are rapidly advancing towards high throughput and low latency, and radar detection is also setting increasingly stringent standards for resolution and detection range. Antennas operating in multiple frequency bands are crucial in these practical applications, particularly in the S-band (2-4 GHz) and Ku-band (12-18 GHz). The S-band is widely used in weather radar, satellite communications, and aerospace communications, while the Ku-band plays a key role in satellite broadcasting, satellite communication ground stations, and high-speed data transmission. Furthermore, to cope with complex and changing electromagnetic environments, circularly polarized antennas are preferred, as they effectively minimize signal fading and multipath interference, ensuring stable and reliable signal transmission. Furthermore, antennas with wide beamwidths can achieve wider signal coverage, reduce signal blind spots, and improve overall system performance.

[0003] However, existing multi-band antennas have significant drawbacks in many areas. In terms of structural design, some antennas employ complex multi-layer nesting or combinations of multiple independent antennas to achieve multi-band functionality. This multi-layer nesting structure not only increases the size and weight of the antenna but also exacerbates interference during internal signal transmission. Combining multiple independent antennas significantly increases the difficulty of antenna installation and commissioning, and electromagnetic compatibility between antennas in different frequency bands is difficult to ensure. From a performance optimization perspective, simultaneously meeting the requirements of both the S-band and Ku-band is extremely challenging. Antennas in different frequency bands differ significantly in impedance matching, gain adjustment, and bandwidth control. Traditional antenna designs struggle to balance these factors, resulting in poor performance in certain frequency bands, often resulting in issues such as severe signal attenuation and excessive standing wave ratios.

[0004] In terms of beamwidth, the beamwidth of common multi-band antennas is relatively narrow. Taking planar array antennas as an example, although they can achieve high gain in specific directions, the beamwidth is often limited to a small angular range. In scenarios requiring large-area signal coverage, such as ground stations receiving signals from multiple satellites in satellite communications, or scanning large areas in radar detection, this can result in ineffective signal coverage in some areas, affecting communication and detection effectiveness. In addition, due to complex structures and improper material selection, many multi-band antennas are heavy. In some weight-sensitive application scenarios, such as communication antennas on drones and payload antennas on satellites, overly heavy antennas increase energy consumption, reduce the device's endurance, and even affect the device's flight stability and orbital life.

[0005] In summary, developing a circularly polarized wide-beam antenna operating in the S-band and Ku-band to overcome the shortcomings of existing technologies and meet the needs of modern communications and detection fields is of extremely important practical significance. Utility Model Content

[0006] In response to the above technical problems, the present invention provides a circularly polarized wide-beam antenna for the S-band and Ku-band, which can be applied to communication systems that need to transmit and receive signals in the S-band and Ku-band, such as satellite communications, radar detection and other fields.

[0007] The utility model is realized by adopting the following technical solutions:

[0008] A circularly polarized wide-beam antenna for S-band and Ku-band frequencies, comprising a conical metal base, an S-band feed network and cavity, a metal support column, an S-band conical logarithmic spiral antenna, a Ku-band conical logarithmic spiral antenna, a Ku-band baseplate, a Ku-band slotted balun, a radome, and two feed coaxial cables; the two feed coaxial cables are semi-flexible cables with insulating sheaths, including an S-band antenna feed cable and a Ku-band antenna feed cable;

[0009] Among them, the S-band conical logarithmic spiral antenna and the Ku-band conical logarithmic spiral antenna both adopt the form of a two-arm conical logarithmic spiral antenna; the spiral is composed of a copper strip electroplated on a cone-shaped plastic, and the copper strip becomes narrower from the bottom of the cone to the top of the cone.

[0010] Specifically, the outer conductor of the S-band antenna feed cable is welded to the bottom of the S-band feed network cavity, and the inner conductor of the S-band antenna feed cable is welded to the main port of the S-band feed network in the form of a PCB. The S-band feed network also includes a microstrip circulator, an extended microstrip line and a connecting microstrip board.

[0011] Specifically, the microstrip circulator of the S-band feeding network includes four ports, port one is a main input port for feeding, port two and port three are output ports, and port four is connected to an external absorption resistor;

[0012] When power is fed from port one, it can output signals with equal amplitude and opposite phase; port four is connected to a 50 ohm absorption resistor to absorb excess energy and improve standing wave performance.

[0013] Specifically, the end with a smaller diameter of the conical metal base is provided with two mounting ears, the end with a larger diameter is provided with the S-band feeding network and the cavity, and the interior of the base is a cavity for accommodating the feeding coaxial cable.

[0014] Specifically, the metal support column is installed together with the S-band feeding network cavity, and impedance gradient microstrip lines are installed on both sides of the metal support column to lead the signals of the two output ports of the S-band feeding network to the top of the support rod; a through hole is provided inside the metal support column for passing the Ku-band antenna feeding cable, and the S-band conical logarithmic spiral antenna is sheathed outside the metal support column.

[0015] Specifically, the top of the metal support column is also provided with a step structure for positioning the feed PCB. The feed PCB is circular, and the impedance-transforming microstrip line and the external spiral copper strip are connected and soldered through two fan-shaped copper-clad areas. The feed PCB is also provided with a support block that separates the Ku-band baseboard from the feed PCB.

[0016] Specifically, the Ku-band base plate is connected to the Ku-band split balun by bolts; the inner conductor of the Ku-band split balun is welded to the inner conductor of the Ku-band antenna feed cable, the outer conductor of the Ku-band split balun is welded to the outer conductor of the Ku-band antenna feed cable, and the two pins on the top are respectively welded to the two arms of the Ku-band conical logarithmic spiral antenna.

[0017] Specifically, a Ku-band split balun quarter-wavelength choke slot is further provided on the outer conductor of the Ku-band split balun.

[0018] Specifically, the antenna cover is made of honeycomb structure material and is installed on the conical metal base.

[0019] The beneficial effects of the present invention are:

[0020] (1) By changing the traditional microstrip to balanced two-line balun feeding form to the S-band circulator + microstrip line form and the Ku-band split balun + coaxial line form, the amplitude and phase changes that guarantee performance are concentrated on the horizontal plane at the bottom of the low-frequency antenna, reducing the influence of the high-frequency feeding structure on it, and more effectively and conveniently achieving the co-aperture radiation of the stacked S-band spiral and Ku-band spiral.

[0021] (2) Both the S-band antenna and the Ku-band antenna adopt the form of a conical logarithmic spiral antenna. The current is transmitted from the top feed point along the spiral arm in a traveling wave manner, which makes this type of antenna have a wide standing wave ratio bandwidth. When the antenna is working, the current propagation speed is slow in the area near the feed point. After entering the effective radiation area, the propagation speed accelerates, forming electromagnetic wave radiation. When the frequency changes, the radiation area moves along the axial direction. The higher the frequency, the closer the radiation area is to the top of the cone. This dynamic adjustment mechanism enables the antenna to maintain stable radiation characteristics within a wide frequency band. The shape of the cone can reduce the back lobe and cross polarization, thereby giving the antenna a wide beam width. The direction of the spiral determines the circular polarization direction of the radiation field. Due to the symmetry of the spiral arm and the traveling wave propagation of the current, the electric field vector rotates with time during the propagation process to form a circularly polarized wave.

[0022] (3) The use of lightweight materials such as aluminum alloy support rods and honeycomb structured FR4 material antenna covers effectively reduces the weight of the antenna, making it suitable for application scenarios with strict weight restrictions. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 the structures shown in these drawings without paying any creative work.

[0024] Figure 1 This is an overall structural diagram of the circularly polarized wide-beam antenna for the S-band and Ku-band in an embodiment of the present utility model;

[0025] Figure 2 Detailed diagram of the Ku-band crack balun in the embodiment of the present utility model;

[0026] Among them, 1-conical metal base, 201-microstrip circulator, 202-extended microstrip line, 203-connecting microstrip board, 3-metal support column, 4-S-band antenna feed cable, 5-Ku-band antenna feed cable, 6-S-band conical logarithmic spiral antenna, 7-Ku-band conical logarithmic spiral antenna, 8-Ku-band bottom plate, 9-Ku-band split balun, 901-Ku-band split balun inner conductor, 902-Ku-band split balun outer conductor, 903-Ku-band split balun quarter-wavelength choke slot, 10-radome. DETAILED DESCRIPTION

[0027] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in 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 some embodiments of the present invention, not all 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.

[0028] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not require further definition or explanation in subsequent drawings.

[0029] The following is combined with Figure 1-2 , some embodiments of the present invention are described in detail. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0030] The utility model proposes a circularly polarized wide-beam antenna for the S-band and Ku-band. Through reasonable antenna selection and layout, the circularly polarized signal reception and transmission functions of the S-band and Ku-band are realized, while the antenna weight is reduced to meet the needs of practical applications.

[0031] In this embodiment, if Figure 1 As shown in the figure, the S-band and Ku-band circularly polarized wide-beam antenna mainly consists of a conical metal base 1, an S-band feeding network and cavity, a metal support column 3, an S-band conical logarithmic spiral antenna 6, a Ku-band conical logarithmic spiral antenna 7, a Ku-band base plate 8, a Ku-band split balun 9, a radome 10, and two feeding coaxial cables. The following is a detailed description of each structure:

[0032] Conical Metal Base 1: This conical stainless steel base features two mounting ears on the smaller end, facilitating pop-up antenna operation. The base has a cavity inside to accommodate the feed coaxial cable. The larger end houses the S-band feed network and cavity.

[0033] Feed coaxial cables: The feed coaxial cables are divided into S-band antenna feed cable 4 and Ku-band antenna feed cable 5. Both use 2# semi-flexible cable with an insulating sheath. This insulating sheath enables the feeder cables to withstand higher operating temperatures, ensuring stable antenna operation in various environments.

[0034] S-band feed network and cavity: The outer conductor of the S-band antenna feed cable 4 is soldered to the bottom of the S-band feed network cavity, while the inner conductor is soldered to the main port of the PCB-based S-band feed network. The S-band feed network is a microstrip circulator 201 with four ports: Port 1 is the main input port for feeding power; Ports 2 and 3 are output ports. When fed from Port 1, they can output signals with equal amplitude and opposite phases; Port 4 is connected to a 50-ohm absorption resistor to absorb excess energy and improve standing wave performance.

[0035] Metal Support Column 3: An aluminum alloy support rod is mounted together with the S-band feed network cavity. Impedance-graded microstrip lines are installed on both sides of the support rod to guide the signals from the two output ports of the S-band feed network to the top of the support rod. A through-hole is provided inside the support rod to facilitate the insertion of the Ku-band antenna feed cable. The S-band helical antenna is sheathed on the outside of the support rod.

[0036] S-Band Conical Logarithmic Spiral Antenna 6 and Ku-Band Conical Logarithmic Spiral Antenna 7: Both the S-Band Conical Logarithmic Spiral Antenna 6 and the Ku-Band Conical Logarithmic Spiral Antenna 7 utilize a two-arm conical logarithmic spiral antenna. The spiral is constructed from copper strip electroplated onto a conical plastic surface. The copper strip narrows from the base of the cone to the top, providing the antenna with a wide beamwidth.

[0037] Feed PCB and Related Connections: The top of the metal support column 3 features a stepped structure for positioning the feed PCB. The feed PCB is circular, with two fan-shaped copper-clad areas connecting the impedance-converting microstrip line and the external spiral copper strip, which are then soldered together to achieve continuous signal transmission. A support block separates the Ku-band antenna base from the feed PCB above the feed PCB. The brass Ku-band split balun 9 is screwed onto the Ku-band baseplate 8, as shown in the following example. Figure 2 As shown, the inner conductor 901 of the Ku-band crack balun is welded to the inner conductor of the Ku-band antenna feeding cable 5, the outer conductor 902 of the Ku-band crack balun is welded to the outer conductor of the Ku-band antenna feeding cable 5, and the two pins on the top of the balun are respectively welded to the two arms of the Ku-band conical logarithmic spiral antenna 7 to realize Ku-band feeding.

[0038] Radome 10: The radome 10 is made of FR4 material with a honeycomb structure and is installed on a stainless steel conical base. It provides good protection for the radiator and reduces the overall weight of the antenna.

[0039] Traditional dual-arm conical logarithmic spiral antennas are fed using a microstrip-to-balanced two-wire balun. Typically, the ends of the balanced two-wire are welded to the spiral arms at the top of the balun to achieve equal-amplitude reverse feeding between the two spiral arms. This traditional approach has limitations for current co-aperture multi-band operation. First, when stacking antennas of different frequency bands, the feed line of the top high-frequency antenna will affect the amplitude and phase of the feed of the bottom low-frequency antenna. Second, the Ku-band's electrical dimensions are very small, which degrades the machining accuracy and assembly difficulty of a microstrip-to-balanced two-wire balun.

[0040] Taking the above two points into consideration, the present invention has made improvements in the antenna feeding structure from the following two aspects: first, the feeding structure of the S-band spiral is changed, the phase change section is concentrated at the bottom of the S-band antenna, and a hollow metal support column is introduced to isolate the internal Ku-band feeding line and the external S-band feeding line to prevent the two from affecting each other; second, the feeding form of the Ku-band antenna is changed to a feeding method using a split Balunga coaxial cable that is easier to process and assemble.

[0041] Based on the first point mentioned above, this solution changes the feeding structure to a circulator + microstrip line. First, the microstrip circulator has four ports. When feeding from port one, ports two and three can output signals with equal amplitude and opposite phases; port four is connected to a 50-ohm absorption resistor to absorb excess energy. Then, a longitudinal microstrip line is extended from port two and port three by welding, and the feeding point is led to the top of the S-band spiral, achieving the same performance as the traditional feeding method. The longitudinal microstrip line extending from the S-band spiral is installed on a hollow metal support column. The support column not only plays a supporting role, but also provides the same grounding level for the two microstrip lines and the circulator. In addition, the space in the center of the support column can be used to accommodate the feeding cable of the top Ku-band antenna, and the metal material of the support column also shields the Ku-band feeding cable to prevent it from affecting the S-band feeding.

[0042] Based on the second point mentioned above, the Ku-band spiral at the top uses a coaxial split balun for feeding. Compared with the traditional microstrip to balanced two-wire balun, this feeding method only requires the inner conductor of the coaxial cable to be connected to the inner conductor of the balun, and the outer conductor of the coaxial cable to be connected to the outer conductor of the balun, which improves the convenience of assembly and the continuity of feeding, and also has better assembly accuracy than microstrip.

[0043] In summary, the utility model changes the traditional microstrip to balanced two-line balun feeding form into the S-band circulator + microstrip line form and the Ku-band split balun + coaxial line form, concentrates the amplitude and phase changes that guarantee performance on the horizontal plane at the bottom of the low-frequency antenna, reduces the influence of the high-frequency feeding structure on it, and more effectively and conveniently realizes the co-aperture radiation of the stacked S-band spiral and Ku-band spiral.

[0044] Both S-band and Ku-band antennas utilize conical logarithmic spiral antennas. Current propagates from the top feed point along the spiral arms as traveling waves, giving this antenna a wide standing wave ratio (SWR) bandwidth. During operation, the current propagates slowly near the feed point. Once in the effective radiation zone, it accelerates, generating electromagnetic radiation. As the frequency changes, the radiation zone shifts axially, with higher frequencies bringing the zone closer to the cone top. This dynamic adjustment mechanism ensures stable radiation characteristics across a wide bandwidth. The conical shape reduces backlobes and cross-polarization, resulting in a wide beamwidth. The handedness of the spiral determines the circular polarization of the radiated field. Due to the symmetry of the spiral arms and the traveling wave propagation of the current, the electric field vector rotates over time during propagation, forming a circularly polarized wave.

[0045] For the sake of simplicity, the aforementioned embodiments are described as a series of actions. However, those skilled in the art should be aware that this application is not limited by the order of the actions described, because according to this application, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in this specification are preferred embodiments, and the actions involved are not necessarily required by this application.

[0046] The above embodiments describe the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Without departing from the spirit and scope of the present invention, modifications and variations made by those skilled in the art without departing from the spirit and scope of the present invention should be within the scope of protection of the appended claims.

Claims

1. A circularly polarized wide-beam antenna for S-band and Ku-band, characterized in that: It includes a conical metal base (1), an S-band feeding network and cavity, a metal support column (3), an S-band conical logarithmic spiral antenna (6), a Ku-band conical logarithmic spiral antenna (7), a Ku-band bottom plate (8), a Ku-band slot balun (9), a radome (10), and two feeding coaxial cables; The two feeding coaxial cables are both semi-flexible cables with insulating sheaths, and include an S-band antenna feeding cable (4) and a Ku-band antenna feeding cable (5).

2. The S-band and Ku-band circularly polarized wide-beam antenna according to claim 1, wherein: The outer conductor of the S-band antenna feed cable (4) is welded to the bottom of the S-band feed network cavity, and the inner conductor of the S-band antenna feed cable (4) is welded to the main port of the S-band feed network in the form of a PCB. The S-band feed network also includes a microstrip circulator (201), an extended microstrip line (202), and a connecting microstrip board (203).

3. The S-band and Ku-band circularly polarized wide-beam antenna according to claim 2, wherein: The microstrip circulator (201) of the S-band feeding network comprises four ports, port one being a main input port for feeding, port two and port three being output ports, and port four being connected to an external absorption resistor.

4. The S-band and Ku-band circularly polarized wide-beam antenna according to claim 1, wherein: The conical metal base (1) has two mounting ears at one end with a smaller diameter, and the S-band feeding network and cavity are installed at the other end with a larger diameter. The interior of the base is a cavity for accommodating the feeding coaxial cable.

5. The S-band and Ku-band circularly polarized wide-beam antenna according to claim 4, wherein: The metal support column (3) is installed together with the S-band feeding network cavity. Microstrip lines with gradient impedance are installed on both sides of the metal support column (3) to lead the signals of the two output ports of the S-band feeding network to the top of the support rod. A through hole is provided inside the metal support column (3) for passing the Ku-band antenna feeding cable (5). The S-band conical logarithmic spiral antenna (6) is sleeved outside the metal support column (3).

6. The S-band and Ku-band circularly polarized wide-beam antenna according to claim 5, wherein: The top of the metal support column (3) is also provided with a step structure for positioning the feed PCB. The feed PCB is circular and is connected to the impedance-transformed microstrip line and the external spiral copper strip through two fan-shaped copper-clad areas and soldered. The feed PCB is also provided with a support block that separates the Ku-band bottom plate (8) from the feed PCB.

7. The S-band and Ku-band circularly polarized wide-beam antenna according to claim 6, wherein: The Ku-band bottom plate (8) is connected to the Ku-band crack balun (9) by bolts; the inner conductor (901) of the Ku-band crack balun is welded to the inner conductor of the Ku-band antenna feed cable (5); the outer conductor (902) of the Ku-band crack balun is welded to the outer conductor of the Ku-band antenna feed cable (5); and the two pins at the top are respectively welded to the two arms of the Ku-band conical logarithmic spiral antenna (7).

8. The S-band and Ku-band circularly polarized wide-beam antenna according to claim 7, wherein: A Ku-band crack balun quarter-wavelength choke slot (903) is also provided on the Ku-band crack balun outer conductor (902).

9. The S-band and Ku-band circularly polarized wide-beam antenna according to claim 1, wherein: The radome (10) is made of a honeycomb structure material and is mounted on the conical metal base (1).

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