Miniaturized microwave slot antenna for solar radio observation and observation device thereof

Abstract

The application provides a miniaturized meter-wave slot-line antenna for solar radio observation and an observation device thereof, and relates to the technical field of antenna design. The antenna comprises a radiation unit and a reflecting plate arranged below the radiation unit. The radiation unit comprises a pair of symmetrical exponential gradient radiation arms, a feeding probe and a resonance cavity. The inside profile of the two exponential gradient radiation arms forms a gradient slot line, and the outside profile is composed of a plurality of straight lines to form a bending profile. The inner core of the feeding probe penetrates from the bottom of one exponential gradient radiation arm, extends to the bottom end of the gradient slot line and is electrically connected to the other exponential gradient radiation arm. The resonance cavity is arranged at the bottom of the two exponential gradient radiation arms and is symmetrically arranged along the symmetry axis of the two exponential gradient radiation arms. The antenna is miniaturized, light-weighted, high-gain and excellent in array adaptability, and is suitable for meter-wave solar flow radio observation.

Description

Technical Field

[0001] This invention relates to the field of antenna design technology, and in particular to a miniaturized meter-wave slot antenna and its observation equipment for solar radio observation. Background Technology

[0002] Solar radio observation is a core means of analyzing solar eruption phenomena, coronal magnetic fields, and high-energy electron acceleration mechanisms. The 30MHz-300MHz meter-wave band can directly reflect the evolution of the corona and interplanetary space, and has unique observational advantages.

[0003] Traditional meter-wave radio observations employ log-periodic, Yagi antennas, resulting in bulky equipment, large footprints, and stringent site selection constraints, making mobile observations and dense array deployments difficult. While Vivaldi slotted antennas are preferred for miniaturization due to their planar, thin, and easily conformally integrated characteristics, their standard half-wavelength structure only achieves impedance matching within a limited narrow band. Impedance fluctuates drastically across the full meter-wave observation bandwidth, leading to poor broadband matching. Mismatch with the substrate-integrated feed network causes significant signal reflections. Signal loss occurs at low-frequency meters-wave frequencies through the dielectric substrate, resulting in low radiation efficiency. The open back of the antenna is susceptible to ground-based RF interference and array element coupling signals, and insufficient backscatter suppression raises the observation noise floor, failing to fully meet the requirements of meter-wave solar observations. Summary of the Invention

[0004] To address the aforementioned issues, this invention proposes a miniaturized meter-wave slot antenna and its observation equipment for solar radio observation. The antenna features a compact structure, wide bandwidth, and high forward radiation efficiency, thus meeting the urgent needs of solar radio observation for miniaturized, portable, and easily arrayed antenna systems.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a miniaturized meter-wave slotted antenna for solar radio observation, comprising a radiating element and a reflector disposed below the radiating element: The radiating unit includes a pair of symmetrical exponentially graded radiating arms, a feed probe, and a resonant cavity; the inner contours of the two exponentially graded radiating arms form a graded groove line, and the outer contours are formed by splicing multiple straight lines to form a bent contour; the inner core of the feed probe enters from the bottom of one exponentially graded radiating arm and extends to the bottom of the graded groove line to be electrically connected with the other exponentially graded radiating arm; the resonant cavity is disposed at the bottom of the two exponentially graded radiating arms and is symmetrically arranged along the axis of symmetry of the two exponentially graded radiating arms.

[0006] As an alternative implementation, the radiating element is vertically disposed on the lower horizontal reflector.

[0007] As an alternative implementation, both the radiating unit and the reflector are frame-type hollow structures with equidistant partition strips arranged inside.

[0008] As an alternative implementation, the inner contours of the two radial arms are formed by an exponentially gradient curve, as shown below: ; in, Let be the projected length of the groove curve on the longitudinal axis. For the gradual scaling factor, and From the starting point of the groove line and the end point The coordinates determine this.

[0009] As an alternative implementation, the gradient groove line is formed by the inner contours of two exponentially gradient radiating arms, and the gaps between the inner sides of the two exponentially gradient radiating arms change continuously and smoothly along the Y-axis from the bottom of the feed to the top of the radiation, forming a gradient groove transmission structure.

[0010] As an alternative implementation, the outer side is formed by splicing multiple straight lines to form a bent profile. Specifically, the outer side of the two exponentially graded radiating arms includes a longitudinally extending straight line segment. After extending to a preset height node, the straight line segment bends and deflects at a preset angle toward the axis of symmetry of the two exponentially graded radiating arms to form a bent aperture edge at the end of the radiating arm.

[0011] As an alternative implementation, the feed probe includes an outer coaxial feed probe outer conductor and an inner coaxial feed probe inner core.

[0012] As an alternative implementation, the resonant cavity is rectangular.

[0013] As an alternative implementation, it also includes arranging multiple sets of the antennas at intervals to form an array antenna.

[0014] In a second aspect, the present invention provides a solar radio observation device, including a radio frequency receiving front-end and a signal processing link; The radio frequency receiving front end includes a receiving unit, and the receiving unit employs an antenna as described in the first aspect.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention abandons the traditional dielectric substrate and adopts an all-metal exponentially graded radiating arm hollow structure, completely eliminating polarization loss caused by meter-wave low-frequency electromagnetic waves penetrating the medium and improving radiation efficiency. The resonant cavity can block stray wave leakage from the surface of the feed end, smooth impedance fluctuations across the entire meter-wave band, alleviate impedance mismatch between the antenna and the feed network, significantly reduce RF signal reflection loss, and achieve excellent broadband matching across the entire frequency band. A reflector plate is provided below the radiating unit to shield the back space, blocking ground RF noise and coupling interference between array units, effectively suppressing back radiation and lowering the observation noise floor. At the same time, the all-metal hollow structure is lightweight and has low wind resistance, which facilitates dense array arrangement of multiple units. The observation gain can be flexibly increased by expanding the array units, taking into account miniaturization, wide bandwidth, and high sensitivity, making it perfectly suited for mobile solar meter-wave radio observation scenarios in the field.

[0016] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute a limitation thereof.

[0017] Figure 1 This is a schematic diagram of the overall structure of a miniaturized meter-wave slotted antenna for solar radio observation provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the radiating unit structure provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the Type III balun coaxial feed probe structure provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of a reflector provided in an embodiment of the present invention; Figure 5 This is a schematic diagram illustrating the variation of S11 with the scaling factor B according to an embodiment of the present invention; Figure 6 This is a schematic diagram illustrating the variation of S11 with height H_1 provided in an embodiment of the present invention; Figure 7 Figure S11 shows the miniaturized meter-wave slotted antenna provided in an embodiment of the present invention; Figure 8 The directional gain diagram at a frequency of 50MHz provided in this embodiment of the invention; Figure 9 This is a directional gain diagram at an 80MHz frequency point provided in an embodiment of the present invention; Figure 10 Directional gain diagram at 110MHz frequency point provided in this embodiment of the invention; Among them, 1-radiating unit; 2-reflector; 3-exponentially graded radiating arm; 4-feed probe; 5-resonant cavity; 6-graded groove line; 7-feed probe outer conductor; 8-feed probe inner core. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0019] Example 1 Next, combined Figure 1 The miniaturized meter-wave slotted antenna for solar radio observation disclosed in this embodiment includes a radiating element and a reflector placed below the radiating element: The radiating unit includes a pair of symmetrical exponentially graded radiating arms, a feed probe, and a resonant cavity; the inner contours of the two exponentially graded radiating arms form a graded groove line, and the outer contours are formed by splicing multiple straight lines to form a bent contour; the inner core of the feed probe enters from the bottom of one exponentially graded radiating arm and extends to the bottom of the graded groove line to be electrically connected with the other exponentially graded radiating arm; the resonant cavity is disposed at the bottom of the two exponentially graded radiating arms and is symmetrically arranged along the axis of symmetry of the two exponentially graded radiating arms.

[0020] The antenna described in this embodiment adopts an all-metal frame structure, combined with an integrated choke cavity and reflector loading, to achieve wide bandwidth and high forward radiation characteristics.

[0021] (I) Overall Antenna Structure The overall structure of the antenna is as follows Figure 1 As shown, it includes a radiation unit 1 and a reflector 2.

[0022] Among them, such as Figure 2 As shown, the radiating element 1 consists of a pair of symmetrical exponentially graded radiating arms 3, a feed probe 4, and an integrated resonant cavity 5. The radiating element 1 has a frame structure, which is made of metal by bending, straightening, and welding. The symmetrical structure of the exponentially graded radiating arms 3 forms a graded groove line 6.

[0023] The reflector 2 is a planar reflector formed by a metal cutout design, perpendicular to the plane of the radiation unit 1, and placed below the radiation unit 1.

[0024] In this embodiment, the antenna is made entirely of metal, abandoning the traditional dielectric substrate. The radiating arm and reflector both adopt a frame-type hollow structure with equidistant partition strips inside. By hollowing out the antenna to remove excess metal and retain the complete conductive radiation outline, the antenna weight is greatly reduced while ensuring electromagnetic performance, reducing wind resistance and facilitating movement and dense arraying. Based on the stable signal acquisition capability of the wideband gradient groove line, it meets the requirements for solar radio current dynamic observation.

[0025] (II) Radial Arm Structure Two identical exponentially graded radial arms 3 are symmetrically arranged. The inner contours of the two radial arms are formed by exponentially graded curves, the expression of which is: ; in, Let be the projected length of the groove curve on the longitudinal axis. For the gradual scaling factor, and From the starting point of the groove line and the end point The coordinates determine this. In simulation modeling, the theoretical continuous exponential curve is discretized into multiple short line segments for fitting, in order to reduce the difficulty of processing.

[0026] Two exponentially tapered radiating arms 3 have their inner arc-shaped edges joined to form a central tapered slot line 6. The gaps on the inner sides of the two arms extend upwards along the Y-axis from the bottom opening of the feed point (to test the effect of adjusting the feed point position), connecting to the exponential curve to achieve a continuous and smooth change in width to the top of the radiation, thus forming a tapered slot transmission structure. The tapered slot line can achieve smooth impedance matching across the entire frequency band, converting the guided wave within the slot into a free-space radiated electromagnetic wave. Adjusting the tapered amplitude of the slot allows control of the antenna bandwidth and radiation beam.

[0027] The outer edges of the two exponentially gradient radiating arms 3 adopt a multi-segment straight line splicing profile, including vertically extending straight line segments. After extending to a preset height node, the outer edges bend and deflect at a preset angle towards the axis of symmetry of the two radiating arms, thus forming a bent-diameter edge at the end of the radiating arms. It should be understood that those skilled in the art can set the preset height and preset angle themselves.

[0028] In this embodiment, the lower part of the antenna is provided with an inward bending structure, which can reduce metal consumption, save manufacturing costs, reduce the overall space occupied by the device, and also improve aesthetics.

[0029] (III) Power supply and balun structure The bottom of the exponentially graded radiating arm 3 has an outwardly protruding coaxial feed probe 4 for docking with an external RF feed line. The feed probe 4 is composed of concentric conductors, such as... Figure 3 As shown, it is specifically a Type III balun coaxial feed probe, including an outer coaxial feed probe outer conductor 7 and an inner coaxial feed probe inner core 8.

[0030] The probe core penetrates from the bottom into one side of the radiating arm, extends to the bottom of the tapered groove line and is electrically connected to the other side of the radiating arm to form an excitation circuit. This provides a balanced radio frequency signal to the radiating arm, stabilizes the antenna's broadband impedance matching and directional beam performance, and ensures complete reception of weak multi-band solar radio signals.

[0031] (iv) Resonant cavity structure A rectangular resonant cavity 5 (choke cavity) symmetrical about the feed point is set up to suppress the common-mode current on the coaxial outer skin, ensuring that energy is coupled only to the slot gap and achieving broadband matching.

[0032] Specifically, the resonant cavity 5 is fitted to the bottom surface of both radiating arms. Utilizing the resonant impedance characteristics designed for the operating frequency band of the coaxial outer conductor, a high-impedance barrier is formed at the feed port. When the common-mode leakage current generated by the coaxial outer sheath reaches the resonant cavity region, it cannot be conducted to the outer edge cable and the outer wall of the radiating arm due to the high impedance boundary. Instead, it is absorbed and dissipated by the resonant cavity, allowing only the radio frequency energy to be transmitted and coupled along the slot gap between the two radiating arms. This eliminates beam distortion and frequency band mismatch problems caused by common-mode current, thereby maintaining a stable impedance matching effect across the entire operating bandwidth and ensuring the broadband electromagnetic reception performance of the tapered slot antenna.

[0033] (v) Loading of the reflector A perforated metal reflector 2 is loaded below the antenna element and on one side of the feed end, with the structure as follows: Figure 4 As shown, the perforated metal structure reduces metal consumption, overall weight, and wind resistance while retaining an effective metal reflective frame, achieving a balance between electromagnetic performance and lightweight materials. The reflector can reflect most of the electromagnetic waves radiated backward by the radiating arm back into the forward space, superimposing them in phase with the electromagnetic waves directly radiated forward by the antenna. This effectively enhances the forward radiation intensity, suppresses backward radiation, and significantly improves the antenna's receiving gain. Only a very small amount of electromagnetic waves are slightly transmitted backward through the perforated holes, having no significant impact on the overall directional detection performance of the antenna. This approach balances the lightweight requirements of dense solar radio array setups with the electromagnetic performance requirements of high-precision signal acquisition.

[0034] In this embodiment, by loading a perforated metal reflector below the radiating element, back radiation is effectively suppressed, and energy is concentrated in the forward half-space, improving antenna gain and achieving good performance while reducing weight. Simulation results show that the antenna has good end-fire characteristics across the entire frequency band, improving forward radiation efficiency.

[0035] (vi) Antenna working principle During antenna transmission, the electromagnetic energy excited by the feed point propagates along the slot line to the open end, and smoothly transitions to free space through the exponentially gradient structure, achieving broadband radiation.

[0036] During the antenna reception process, spatial electromagnetic waves are coupled to the feed point along the opposite path and received by the receiver.

[0037] Once designed, a single slotted antenna element can achieve a forward radiation characteristic. By arranging two elements side-by-side at a certain spacing to form a binary array, higher gain or narrower beam pointing can be achieved. Similarly, by simply expanding the number of elements to three, four, five, etc., different array gains and beam control capabilities can be achieved to meet the antenna sensitivity and radiation pattern requirements of different observation scenarios.

[0038] In this embodiment, the antenna structure is regular, which facilitates the formation of an array. The coherent superposition principle can be used to further improve the system gain, laying the foundation for building a high-sensitivity, high-time-resolution solar radio observation array.

[0039] As one implementation method, key antenna parameters are determined through simulation optimization. Determining the basic antenna dimensions requires optimizing key variables through parameter scanning to achieve good matching across a wide bandwidth. The main optimization parameters include the scaling factor B and the electrical height H.

[0040] The scaling factor B determines the rate at which the radiating arm opens, directly affecting the impedance transition characteristics between the antenna and space. To investigate the effect of B, simulations were conducted with a fixed electrical height and varying the value of B, yielding the VSWR (Standing Wave Ratio) variation curve, as shown below. Figure 5 As shown. Simulation results show that when B is small (B<6), the gradient is too gentle, the antenna matching is poor, and the VSWR gradually decreases as B increases; when B is too large (B>6), the gradient is too steep, resulting in enhanced mid-frequency reflection, and the VSWR gradually increases as B increases; near B=6, the antenna achieves the best matching in the entire frequency band, and S11 is generally below -10dB.

[0041] The electric height H reflects the antenna's size relative to the wavelength. By fixing B=6 and varying H during simulation, the VSWR (Standing Wave Ratio) variation curve is obtained, as shown below. Figure 6 As shown. Simulation results show that the antenna matching shifts towards lower frequencies as the height H_1 increases, improving matching in the low-frequency band, while the radiation capability gradually decreases and matching becomes difficult in the high-frequency band; further increasing the antenna height beyond H_1=1250 is not conducive to miniaturization in the designed frequency band.

[0042] Therefore, taking into account both performance and size, the key antenna parameters are finally determined as follows in this embodiment: The scaling factor B = 6; Antenna electrical altitude ; Choke cavity depth ; The distance between the two radiating arms at the feed point .

[0043] like Figure 7The simulated S11 diagram of the antenna shown demonstrates that the antenna provided in this embodiment, through its exponentially tapered radiating arm and integrated choke cavity design, achieves an S11 better than -10dB in the frequency range of 40MHz to 120MHz, and can be roughly used near 120MHz. This indicates that the antenna has good impedance matching characteristics in this frequency band. The antenna covers the main frequency band for solar radio meter-wave observation across the entire frequency band, exhibiting good radiation efficiency and receiving sensitivity within this band, meeting the wideband monitoring requirements for solar radio burst signals.

[0044] In addition, the 3D gain patterns of the antenna in this embodiment at low frequency (50MHz), mid frequency (80MHz), and high frequency (110MHz) are as follows: Figure 8-10 As shown.

[0045] Simulation results show that the antenna has good end-fire characteristics, with the main lobe pointing towards the slot opening direction (0°); the low-frequency beamwidth is wider and the high-frequency beamwidth is narrower, which conforms to the general rules of traveling wave antennas; the antenna gain is in the full frequency band, with lower gain at the low-frequency end and higher gain at the high-frequency end.

[0046] The radiation pattern shows that the antenna has excellent end-fire radiation characteristics, with the main lobe stably pointing towards the slot opening direction and a significant front-to-back ratio, effectively suppressing back-to-back noise and ground reflection interference. As the frequency increases from 40MHz to 120MHz, the antenna's half-power beamwidth (HPBW) exhibits a gradual trend from wide to narrow: the beamwidth is wider at low frequencies, enabling large-area coverage; the beamwidth narrows significantly at high frequencies, enhancing directivity. This pattern is consistent with the basic radiation mechanism of traveling-wave antennas. The gain frequency response shows that the antenna gain increases monotonically with frequency across the entire frequency band, with lower gain at low frequencies and higher gain at high frequencies. This characteristic perfectly matches the practical needs of solar radio observation—the low-frequency band is beneficial for wide-angle surveys to capture large-scale coronal bursts, while the high-frequency band provides a narrower beam and higher spatial resolution, creating favorable conditions for subsequent interferometric array formation for synthetic aperture imaging.

[0047] This specific embodiment employs a dielectric-free, all-metal radiating arm structure, eliminating dielectric polarization loss and addressing the low-frequency radiation efficiency problem at its source. A rectangular resonant cavity is symmetrically arranged along the radiating arm to suppress surface wave leakage at the feed point, smoothing the impedance curve across the entire meter-wave band, reducing signal reflection caused by antenna-feed network mismatch, and widening the effective matching bandwidth. A reflector is added to the bottom of the radiating unit to isolate back-side ground interference and array crosstalk, enhancing back-radiation suppression capabilities and reducing the observation noise floor. The entire structure is compact, lightweight, and easy to assemble, providing a reliable hardware solution for high-sensitivity mobile solar radio observations.

[0048] Example 2 This embodiment provides a solar radio observation device, including a radio frequency receiving front-end and a signal processing link; The radio frequency receiving front end includes a receiving unit, and the receiving unit uses an antenna as described in Embodiment 1 above.

[0049] In one implementation, the antenna serves as the core receiving unit of the radio frequency receiving front end. It can receive solar radio broadband electromagnetic wave signals in real time through spatial coupling, and convert the acquired spatial radio frequency signals into weak electrical signals for output. The output electrical signals are connected to the back-end signal processing link to complete signal preprocessing and spectrum analysis, and finally achieve effective capture and observation analysis of solar radio signals.

[0050] It should be understood that the specific composition of the signal processing link can be set by those skilled in the art according to the actual observation frequency band and performance requirements, as long as it can complete the functions of radio signal conditioning, acquisition and analysis. This embodiment does not make specific limitations here.

[0051] Thanks to its compact antenna structure and integrated design, the entire RF front-end is highly modular, enabling it to cover the 40MHz–120MHz frequency band with minimal size and weight. This wideband receiving capability is suitable for fully capturing broadband transient phenomena such as solar type II and type III radio bursts, and can provide continuous dynamic spectral information for studying coronal shock propagation and high-energy electron beams.

[0052] By configuring the antenna as the core receiving unit at the receiving end, not only can the system complexity and hardware cost be significantly reduced, but it can also be flexibly deployed to field sites with quiet electromagnetic environments, effectively avoiding urban man-made radio frequency interference, thus laying a key hardware foundation for mobile observation and dense array networking of solar radio astronomy.

[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A miniaturized microwave slotline antenna for solar radio observations, characterized in that, Includes a radiating element and a reflector placed below the radiating element: The radiating unit includes a pair of symmetrical exponentially graded radiating arms, a feed probe, and a resonant cavity; the inner contours of the two exponentially graded radiating arms form a graded groove line, and the outer contours are formed by splicing multiple straight lines to form a bent contour; the inner core of the feed probe enters from the bottom of one exponentially graded radiating arm and extends to the bottom of the graded groove line to be electrically connected with the other exponentially graded radiating arm; the resonant cavity is disposed at the bottom of the two exponentially graded radiating arms and is symmetrically arranged along the axis of symmetry of the two exponentially graded radiating arms.

2. The miniaturized meter-wave slot-line antenna for solar radio observation according to claim 1, wherein The radiation unit is vertically positioned on the lower horizontal reflector.

3. The miniaturized meterwave slotline antenna for solar radio observations as claimed in claim 1, wherein, Both the radiating unit and the reflector are frame-type hollow structures with equidistant partition strips arranged inside.

4. The miniaturized meter-wave slotted antenna for solar radio observation as described in claim 1, characterized in that, The inner contours of the two radial arms are formed by exponentially gradient curves, represented as follows: ； in, Let be the projected length of the groove curve on the longitudinal axis. For the gradual scaling factor, and From the starting point of the groove line and the end point The coordinates determine this.

5. The miniaturized meter-wave slotted antenna for solar radio observation as described in claim 1, characterized in that, The gradient groove is formed by the inner contours of two exponentially gradient radiating arms. The gaps between the inner sides of the two exponentially gradient radiating arms change continuously and smoothly along the Y-axis from the bottom of the feed to the top of the radiation, forming a gradient groove transmission structure.

6. The miniaturized meter-wave slotted antenna for solar radio observation as described in claim 1, characterized in that, The outer side is composed of multiple straight lines spliced ​​together to form a curved profile. Specifically, the outer side of the two exponentially gradient radiating arms includes a vertically extending straight line segment. After extending to a preset height node, the straight line segment bends and deflects at a preset angle toward the axis of symmetry of the two exponentially gradient radiating arms to form a curved aperture edge at the end of the radiating arm.

7. The miniaturized meter-wave slotted antenna for solar radio observation as described in claim 1, characterized in that, The feed probe includes an outer coaxial feed probe outer conductor and an inner coaxial feed probe inner core.

8. The miniaturized meter-wave slotted antenna for solar radio observation as described in claim 1, characterized in that, The resonant cavity is rectangular.

9. The miniaturized meter-wave slotted antenna for solar radio observation as described in claim 1, characterized in that, It also includes arranging multiple sets of the antennas at intervals to form an array antenna.

10. A solar radio observation device, characterized in that, This includes the radio frequency receiving front-end and the signal processing link; The radio frequency receiving front end includes a receiving unit, and the receiving unit employs an antenna as described in any one of claims 1-9.

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