A ring probe nested transceiver antenna and microwave measurement system for close-range measurement

Abstract

This invention discloses a short-range measurement system using a nested ring probe antenna and microwave measurement system, belonging to the field of microwave antenna technology. The antenna employs a nested, integrated transmitting and receiving structure, comprising a multi-sector truncated transmitting radiator (N≥4, where N is even) designed based on a sub-rotational symmetry group, a probe receiving antenna nested at its center, a feeding structure, a dielectric substrate, and a ground plane. Through the multi-sector symmetry structure and the principle of phase cancellation, higher-order resonant modes are effectively suppressed, achieving a single main resonance only within the target frequency band. The nested layout ensures high overlap between the transmitting and receiving beams within a preset angle range, improving signal reception purity and suppressing multipath interference. This antenna features a compact structure, high gain, extremely narrow bandwidth, excellent impedance matching, and circular polarization performance, making it suitable for high-precision short-range microwave measurement systems in fields such as precision manufacturing, medical monitoring, and aerospace. It can accurately detect parameters such as displacement, distance, and vibration.

Description

Technical Field

[0001] This invention relates to the field of microwave antenna technology, specifically to an antenna structure and microwave measurement system for microwave short-range measurement, particularly a multi-sector truncated ring probe transceiver antenna based on mode suppression and nested layout. It is suitable for high-precision millimeter-level measurement scenarios such as displacement, distance, and vibration, and is especially suitable for scenarios such as precision manufacturing online monitoring, medical equipment short-range sensing, and aerospace micro-component inspection where there are stringent requirements for polarization stability and resistance to multipath interference. Background Technology

[0002] Millimeter-level close-range measurement has significant application value in fields such as precision manufacturing, medical monitoring, and aerospace. Microwave methods, with their advantages of being non-contact, having strong anti-interference capabilities, and offering moderate spatial resolution, have become an effective technical means for achieving high-precision close-range measurements. As a key component of a microwave measurement system, the performance of the antenna directly affects the system's measurement accuracy, stability, and applicability.

[0003] Loop probe antennas have attracted widespread attention in short-range measurement due to their compact structure, flexible design, and easy-to-adjust radiation pattern. However, traditional loop probe antennas suffer from several significant technical drawbacks: First, the inherent multi-frequency resonance phenomenon, where resonance occurs at multiple frequencies, leads to an impure signal spectrum, interfering with target signal extraction, especially in narrowband radar systems requiring single-frequency operation; second, while pursuing miniaturization, it is difficult to simultaneously maintain antenna performance (such as gain, bandwidth, and matching characteristics). Excessive antenna size introduces significant near-field coupling effects, reducing measurement accuracy, while insufficient size sacrifices gain and bandwidth; third, although some improved antennas in existing technologies employ multi-sector structures, they are mostly based on ordinary sector element designs. The lack of consideration for fan-shaped edge structure optimization and the absence of a proportional relationship between unit gap and truncation width lead to insufficient long-term stability of mode suppression effect, making it prone to resonance shift in complex temperature and humidity environments. Fourth, existing designs generally lack clear constraints on power coupling efficiency and axial ratio fluctuation in the overlapping area of ​​transmit and receive beams. Even if there is partial beam overlap, it is difficult to guarantee signal reception purity under complex operating conditions, and the multipath interference suppression effect is limited. In addition, existing antennas still have shortcomings in suppressing near-field coupling, improving circular polarization purity, and achieving a compact layout for integrated transmission and reception, which further limits the improvement of measurement accuracy.

[0004] Therefore, there is an urgent need for a new antenna design that can effectively suppress multi-frequency resonance, improve mode suppression stability, achieve structural miniaturization, and at the same time take into account good radiation characteristics, high signal reception purity, and integrated transceiver performance. Summary of the Invention

[0005] Based on this, it is necessary to address the multi-frequency resonance problem of traditional loop probe antennas. This application uses a multi-sector truncation structure and the phase cancellation principle to retain only a single resonance in the target frequency band. To address the issue of size and performance compatibility, a nested layout is adopted to achieve compact integrated transmission and reception. To address the near-field coupling problem, the coupling interference is suppressed by precisely controlling the truncation width and feed position, taking into account miniaturization, high gain and narrowband characteristics, to meet the needs of high-precision close-range measurement in multiple scenarios.

[0006] This application provides a ring probe nested transceiver antenna for close-range measurement. The antenna comprises a multi-sector truncated radiating element, a central probe receiving antenna, a feeding structure, a dielectric substrate, and a ground plane. The multi-sector truncated radiating element consists of N identical sector-shaped conductor units arranged symmetrically around an Nth-order rotational symmetry group (N≥4 and even), used to transmit microwave signals. Each sector-shaped conductor unit has a 0.1 mm~0.3 mm arc-shaped chamfered edge on its radial edge, and there are gaps between the sector-shaped units. The central probe receiving antenna is nested in the central region of the multi-sector truncated radiating element to receive echo signals reflected from the target, achieving integrated transceiver functionality. The feeding structure is connected to both the multi-sector truncated radiating element and the central probe receiving antenna to provide feeding excitation. Both the multi-sector truncated radiating element and the central probe receiving antenna are mounted on a dielectric substrate, and a metal ground plane is provided at the bottom of the dielectric substrate.

[0007] Furthermore, the multi-sector truncated radiating body is a truncated structure designed based on an Nth-order rotational symmetry group (N≥4, and N is even), and the effective electrical length of each sector unit is 1 / N of the corresponding complete ring structure;

[0008] Furthermore, each sector conductor unit has a 0.1 mm to 0.3 mm arc-shaped chamfer structure on its radial edge to reduce edge electromagnetic scattering.

[0009] Furthermore, the multi-sector truncated radiating element is arranged with N rotational symmetry (N≥4 and is an even number) to ensure that the feed phase of each sector conductor unit satisfies an equidistant offset relationship (the offset is...). For the inherent nth-order higher-order resonant modes of a loop antenna, the current distribution on the loop is as follows: The periodic variation of the current means that when n ≠ N×m (m is a positive integer), the phase difference of the current in different sector units exactly satisfies the 'pairwise opposite' cancellation condition—that is, the current in the k-th sector unit is out of phase with the current in the (k+N / 2)-th sector unit. The electromagnetic radiation generated by the two cancels each other out in space, resulting in the joint current of the higher-order modes. This completely suppresses the excitation of higher-order resonances.

[0010] Furthermore, higher-order resonant modes are suppressed through the phase cancellation principle, retaining only a single resonant response within the target frequency band: the sector is rotated symmetrically through N rotations and offset from the feed phase by an equal distance (the offset is...). / N) synergistic effect, making the non-target order ( The current phases of the two modes are opposite to each other. After the spatial electromagnetic superposition cancels each other out, the joint current of the higher-order modes is 0, ensuring the sharpness and stability of the single resonance. Its feed phase relationship satisfies:

[0011] ;

[0012] in, Indicates the first Current distribution in a sector-shaped conductor unit, =0,1,2…N;

[0013] for The current distribution on the ring is in the first-order mode. The combined current on the multi-sector cutoff radiating body is:

[0014] ;

[0015] The combined current of the multi-sector truncated radiating body satisfies the following expression:

[0016] ;

[0017] In the formula For the combined current, The order of the pattern. The phase angle, It is a positive integer;

[0018] Furthermore, the outer radius of the multi-sector truncated radiating body The inner radius is 4 mm to 10 mm. The diameter is 3mm to 6mm;

[0019] The radius of the central probe receiving antenna The diameter is 3 mm to 6 mm;

[0020] The cutoff width between the multi-sector truncated radiator and the central probe receiving antenna The thickness is 0.5 mm to 2 mm;

[0021] The dimensions of the metal ground plate The diameter is 8 mm to 12 mm;

[0022] The thickness of the dielectric substrate It ranges from 0.3 mm to 1 mm;

[0023] The distance between the feed point and the center of the multi-sector radiating element The diameter is 3 mm to 8 mm;

[0024] The distance between the feed point of the central probe receiving antenna and the center It is 1 mm to 3 mm.

[0025] The above range is a general adaptation range for the number of sectors N≥4 (even number). Different N values ​​need to be adjusted specifically within this range.

[0026] Furthermore, the target frequency band of the antenna is the millimeter wave band of 18 GHz to 30 GHz, and the target frequency point is any frequency point within the band;

[0027] The antenna has a reflection coefficient of ≤-40 dB and a fluctuation of ≤5 dB within a target frequency range of ±0.5 GHz; a relative bandwidth of 0.1%~0.5% and a gain fluctuation of ≤0.8 dBi within the bandwidth, ensuring performance stability under complex operating conditions; and an absolute bandwidth of ≤0.2 GHz.

[0028] Furthermore, taking the target frequency of 24 GHz as an example, the axial ratio within the range of ±1 GHz is less than 3 dB, exhibiting excellent circular polarization radiation characteristics;

[0029] Preferably, the axial ratio is less than 3 dB in the 23.74 GHz to 24.23 GHz frequency band, and the axial ratio is as low as 1.555 dB at 23.95 GHz.

[0030] Preferably, the specific parameters of the circular polarization performance of the antenna through multi-sector truncation of the radiating element are as follows:

[0031] The radius of the central probe receiving antenna It is 4.32 mm;

[0032] The multi-sector cutoff radiating body ( outer radius It is 8.28 mm, inner radius It is 4.86mm;

[0033] The cutoff width between the multi-sector radiating element and the central probe receiving antenna It is 0.96 mm;

[0034] The dimensions of the metal ground plate It is 9 mm;

[0035] The thickness of the dielectric substrate It is 0.508 mm;

[0036] The location of the multi-sector emitting radiator metal probe It is 5.22 mm;

[0037] The position of the center probe receiving antenna metal probe It is 2.44 mm.

[0038] Furthermore, the cut-off width It is a sensitive and controllable parameter, and its value directly affects the antenna impedance matching characteristics. By precisely adjusting this parameter, the optimal matching of the target frequency can be achieved.

[0039] Preferably, when the cut-off width The antenna performance is optimal when the reflection coefficient is 0.96 mm. A deviation of 0.08 mm from this parameter will lead to a significant deterioration in the reflection coefficient. Therefore, it is necessary to combine multi-parameter collaborative optimization to ensure the stability of antenna performance.

[0040] Furthermore, the average annular width of the sector , ( To cut off the outer radius of the emitted radiation in multiple sectors, The inner radius is 1.64 mm to 2.04 mm. When this parameter changes, the main resonant frequency of the transmitter stabilizes near the target frequency band (absolute deviation ≤ 0.12 GHz), but it will cause the matching frequency of the receiver to shift, which needs to be compensated by multi-parameter collaborative optimization.

[0041] Furthermore, it also includes the simulation and experimental optimization of parameter combinations based on N=4 (quaternary sector structure). When the number of sectors N is 6, 8, or other even numbers ≥4, multi-parameter collaborative optimization needs to be performed again to ensure that the antenna mode suppression effect matches the transmit and receive performance.

[0042] Furthermore, the nested layout ensures that the transmit beam of the multi-sector truncated transmitting radiator and the receive beam of the central probe receiving antenna highly overlap within a preset angle range, achieving directional transmission and reception and multipath interference suppression. The half-power angle coverage range of the transmit beam is 180°~270°, and the receive beam forms a high overlap region of 20°~60° within the main lobe region of the transmit beam. The power coupling efficiency within this overlap region is ≥85%, and the axial ratio fluctuation is ≤1 dB, significantly improving the anti-interference capability of directional transmission and reception.

[0043] Preferably, this parameter combination is based on simulation and experimental optimization of N=4 (quaternary sector structure) and is suitable for application scenarios with N=4. When the number of sectors N is 6, 8 or other even numbers ≥4, multi-parameter collaborative optimization needs to be performed again within the parameter range defined in claim 5 to ensure that the antenna mode suppression effect matches the transmit and receive performance. The transmission beam coverage angle of the multi-sector truncated radiating element is 0°~120° and 240°~360°. The receiving beam of the central probe receiving antenna highly overlaps with the transmission beam in the ranges of 0°~32° and 328°~360°. The transmission beam coverage angle and the overlapping range of the receiving beam corresponding to different N values ​​(N≥4 and even) need to be adapted by adjusting the symmetry parameters: when N increases, the transmission beam coverage angle can be further widened, and the overlapping angle range of the receiving beam and the transmission beam needs to be optimized synchronously to ensure the core requirement of not less than 20°; when N=6, the recommended overlapping angle range is 0°~35° and 325°~360°, and when N=8, the recommended overlapping angle range is 0°~38° and 322°~360°. Specifically, it needs to be verified by full-wave simulation in combination with the target frequency.

[0044] Furthermore, the resonant frequency of the central probe receiving antenna is determined by its self-inductance. and capacitor The decision, expressed as:

[0045] ;

[0046] In the formula, The resonant frequency, For self-awareness, It is a capacitor.

[0047] Among them, self-awareness and capacitor Satisfy the following expression:

[0048] ,

[0049] ;

[0050] In the formula: The permeability of free space, , , Let be the area of ​​the loop antenna. , The vacuum permittivity, , is the dielectric constant of the substrate.

[0051] Furthermore, the fundamental mode resonant frequency of the multi-sector truncated radiating element is determined by both the effective electrical length and the dielectric properties, and is expressed as:

[0052] ;

[0053] In the formula, The fundamental mode resonant frequency, At the speed of light, The average annular width of the sector. This represents the equivalent length compensation introduced by the feed gap. For the effective dielectric constant, Number of sector units ( ≥4, and (is a positive integer).

[0054] Furthermore, the dielectric substrate is a high-frequency board with a dielectric constant of 2.2~4.4 and a dielectric loss tangent of ≤0.004 (@10GHz). The upper surface is coated with an anti-reflection coating with a thickness of 0.05 mm~0.1 mm, which can reduce electromagnetic energy reflection loss and improve radiation efficiency. The dielectric substrate material includes, but is not limited to, [materials not specified in the original text]. , , , , , Anti-reflective coating materials include, but are not limited to: magnesium fluoride ( ), silicon dioxide ( ), tetrafluoroethylene ( It is made of one or more of the following composite materials, with a coating thickness of 0.05 mm to 0.1 mm, a dielectric loss tangent of ≤0.001 (@10 GHz to 30 GHz), and an adhesion to the dielectric substrate of ≥5 N / cm².

[0055] Preferably, the dielectric substrate is made of RO 4350B board with a dielectric constant of 3.66, a dielectric loss angle of 0.0037@10GHz, and a thickness of [missing information]. =0.508 mm; the anti-reflective coating material is silicon dioxide ( ).

[0056] Furthermore, the actual manufacturing dimensional error of the antenna is ≤0.056%, and the corresponding center frequency offset is ≤0.15GHz, which is within a reasonable fluctuation range;

[0057] Furthermore, the physical test performance of the antenna meets the following requirements: the optimal operating frequency is within the 18 GHz~30 GHz band, the reflection coefficient of the transmitting antenna is ≤-42 dB, the reflection coefficient of the receiving antenna is ≤-49 dB, the absolute bandwidth of the transmitting antenna is as low as 0.027 GHz (corresponding to a relative bandwidth of approximately 0.11% at the 24.14 GHz frequency point), and the absolute bandwidth of the receiving antenna is 0.164 GHz (relative bandwidth of approximately 0.68%), all of which are less than 1%. This narrowband requirement makes it suitable for short-range high-precision measurement scenarios with high frequency stability requirements, and provides a novel ring probe antenna solution with a compact structure and strong radiation directionality for short-range high-precision radar systems.

[0058] The present invention discloses a short-range microwave measurement system, comprising a ring probe nested with a transceiver antenna. The ring probe nested with a transceiver antenna is used to transmit microwave detection signals and receive echo signals from the object under test. Through the interaction of the detection signals and echo signals, short-range measurement of the object under test is achieved, acquiring displacement, distance (measurement accuracy ≤ ±0.05 mm) or vibration (vibration frequency range 1 Hz to 1 kHz) information of the object under test within a measurement range of 1 mm to 50 mm, and the system has an anti-electromagnetic interference capability ≥ 40 dB.

[0059] This invention addresses the core technical challenges of traditional loop probe antennas in close-range, high-precision measurement scenarios, precisely overcoming existing technological bottlenecks and specifically solving the following problems:

[0060] Traditional loop probe antennas inherently exhibit multi-frequency resonance, which leads to impure signal spectrum and severely interferes with target signal extraction. This problem directly affects the accuracy and stability of the measurement signal, especially in scenarios such as narrowband radar systems that require single-frequency operation, and fails to meet the signal purity requirements of high-precision measurements.

[0061] In traditional designs, it is difficult to balance antenna size and performance. Too large a size will introduce significant near-field coupling effects, reducing measurement accuracy; too small a size will sacrifice key performance characteristics such as gain and bandwidth, failing to simultaneously meet the requirements of miniaturized installation and the good radiation characteristics required for high-precision measurement, thus limiting its application in scenarios with strict requirements for equipment size, such as precision manufacturing and aerospace.

[0062] Existing antenna designs are inadequate in suppressing near-field coupling. Electromagnetic coupling between the transmitting and receiving units can affect signal transmission quality. At the same time, the low overlap between the transmitting and receiving beams makes them susceptible to multipath interference, which makes echo signal extraction difficult and further reduces measurement accuracy.

[0063] Traditional loop antennas have poor circular polarization performance, resulting in insufficient signal stability in measurement scenarios where polarization purity is required. Furthermore, their impedance matching characteristics need optimization, and their high reflection coefficient leads to significant signal transmission loss, affecting the antenna's energy utilization efficiency and measurement reliability.

[0064] Existing antenna designs are not well-suited for close-range measurement requirements in the 18 GHz to 30 GHz millimeter wave band. They lack dedicated structural designs for this band and struggle to achieve a balance between single resonant response and narrowband characteristics within this band.

[0065] Based on the core technical features described above, this invention achieves the following significant beneficial effects through innovative methods such as multi-sector truncated structure, nested layout, and precise parameter design, fully meeting the stringent requirements of close-range high-precision measurement:

[0066] 1. A multi-sector truncated radiator based on an Nth-order rotational symmetry group (N≥4 and even) is employed. Through phase cancellation, the joint current of non-target orders is reduced to zero, retaining only the single main resonant response within the target frequency band of 18 GHz to 30 GHz. This completely solves the signal interference problem caused by multi-frequency resonance in traditional loop antennas. Actual measurements show that the antenna's relative bandwidth is less than 1%, and its absolute bandwidth is ≤0.2 GHz. Within the optimal range, the absolute bandwidth is as low as 0.027 GHz to 0.1 GHz, providing a clean spectral environment for accurate target signal extraction.

[0067] 2. Through an integrated design of "multi-sector truncated structure + nested central probe layout", the antenna size is significantly reduced while ensuring excellent radiation performance. The radial dimension of the antenna is reduced by more than 65% compared with similar designs, the metal ground plane size is only 8 mm~12 mm, and the dielectric substrate thickness is 0.3 mm~1 mm. The structure is compact and small, which can be adapted to the narrow installation space of precision manufacturing equipment, medical monitoring instruments, etc. At the same time, the maximum radiation gain at the target frequency is ≥8 dBi, the preferred value is ≥11 dBi (measured at 11.028 dBi), which takes into account the requirements of miniaturization and high gain, and breaks through the performance bottleneck of traditional designs.

[0068] 3. By precisely controlling the cutoff width (0.5 mm to 2 mm) between the multi-sector cutoff radiator and the center probe receiving antenna and the feed position (3 mm to 8 mm from the center for the multi-sector feed point, and 1 mm to 3 mm from the center for the receiving antenna feed point), near-field coupling between the transceiver units is effectively suppressed; the nested layout ensures that the transmit beam coverage angle is not less than 180°, and the overlap angle between the receive beam and the transmit beam is not less than 20° (the overlap range is 0° to 32° and 328° to 360° when N=4), thus achieving directional transmission and reception and significantly reducing the impact of multipath interference on the measurement results.

[0069] 4. The antenna has a reflection coefficient of ≤-40 dB at the operating frequency (measured as low as -42.807 dB at the transmitter and -49.594 dB at the receiver), excellent impedance matching characteristics, significantly reducing signal transmission loss and improving energy utilization efficiency; the axial ratio is less than 3 dB within ±1 GHz of the target frequency (satisfied in the 23.74 GHz~24.23 GHz band, with an optimal value of 1.555 dB@23.95 GHz), and has excellent circular polarization radiation characteristics, which can resist signal attenuation caused by polarization mismatch and enhance the stability and reliability of measurement signals under complex working conditions.

[0070] 5. The dielectric substrate uses high-frequency board material with a dielectric constant of 2.2~4.4 (preferably RO 4350B, FR-4, etc.). The structural parameters can be flexibly adjusted within a reasonable range to adapt to different target frequencies. When the actual machining size error is ≤0.056%, the center frequency deviation is ≤0.15 GHz, and the performance stability is strong. At the same time, this antenna can be directly integrated into a short-range microwave measurement system and is widely applicable to precision manufacturing, medical monitoring, aerospace and other fields to achieve accurate detection of displacement, distance or vibration information of the measured object. It has a wide range of applications and strong practicality.

[0071] 6. When the average annular width of the sector of the multi-sector truncated radiating body changes, the absolute deviation of the main resonant frequency at the transmitting end is ≤0.12 GHz, indicating high frequency stability. Through multi-parameter collaborative optimization, the performance fluctuations caused by processing and assembly errors and dielectric material parameter deviations can be effectively compensated. The measured results and simulation results are highly consistent, proving that the design has good robustness and repeatability, and is convenient for mass production and industrial application. Attached Figure Description

[0072] Figure 1 This is a diagram illustrating the evolution of a truncated ring probe nested transceiver antenna in one embodiment;

[0073] Figure 2 In one embodiment, multiple sectors ( =4) Probe antenna Comparison chart of simulation optimization results;

[0074] Figure 3 This is a comparison chart of the iterative performance of a novel truncated ring probe nested transceiver antenna in one embodiment;

[0075] Figure 4 This is a 3D radiation pattern of a novel truncated ring probe nested transceiver antenna in one embodiment;

[0076] Figure 5 Here is a radiation pattern of a novel truncated ring probe nested transceiver antenna in one embodiment;

[0077] Figure 6 The axial ratio curve of the radiating element of the novel truncated ring probe nested transceiver antenna in one embodiment (22GHz-26GHz).

[0078] Figure 7 This is a comparative diagram of similar loop antenna structures in one embodiment;

[0079] Figure 8 Different cut-off width parameters in one embodiment Lower antenna curve;

[0080] Figure 9 Different feed sizes in one embodiment Lower antenna curve;

[0081] Figure 10 Different ring widths in one embodiment Lower radiating unit Line graph;

[0082] Figure 11 Different radii in one embodiment Lower circular antenna Line graph;

[0083] Figure 12 Here is a physical diagram of a truncated loop probe antenna in one embodiment;

[0084] Figure 13 This is a comparison chart of actual test results for a truncated loop probe antenna in one embodiment;

[0085] Figure 14 This is a frequency point and gain offset analysis diagram based on manufacturing and assembly errors in one embodiment;

[0086] Figure 15 This is a frequency point and gain offset analysis diagram based on the dielectric material parameter deviation in one embodiment. Detailed Implementation

[0087] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0088] Example 1

[0089] This embodiment uses N=4 as an example for detailed explanation. Its core design principles are: modal suppression, nested layout, and parameter collaborative optimization. It is applicable to all even-numbered sector structures with N≥4, but the specific size parameters and performance indicators need to be re-optimized according to the N value. The data in the following embodiment are only for the specific implementation of N=4 and do not constitute a limitation on other N values.

[0090] like Figure 1 This demonstrates the design evolution of the antenna of the present invention. Starting from a traditional complete ring probe antenna (a), it first evolved into a single sector element (b), and then expanded to... The four-element sector structure (c) is based on a fourth-order rotational symmetry group design and is a typical implementation of a multi-sector truncated structure. Finally, by nesting a central probe receiving antenna (circular in this embodiment, but other adaptable shapes such as polygons can also be used) at the center of the four-element sector structure, the "truncated ring probe nested transceiver antenna" (d) described in this invention is formed. The core of this evolution lies in: breaking the ring continuity through structural truncation, utilizing the symmetry characteristics of multiple sectors to suppress multimode resonance; and achieving compact transceiver integration through nested layout, balancing miniaturization and performance compatibility.

[0091] To verify the universality of the mode suppression principle, this embodiment uses a four-element sector probe antenna as a basis for simulation testing. The radial edge chamfer of the sector conductor element is 0.12 mm. The results are as follows: Figure 2 As shown, the quadri-element sector probe antenna successfully optimized multiple resonant points of a traditional loop antenna into a single main resonant point (24.03 GHz). The main resonant point is stable and has an extremely narrow bandwidth, which initially proves the effectiveness of the "multi-sector structure + phase cancellation" design concept.

[0092] Based on the four-element sector probe antenna, a central probe receiving antenna is introduced to form a complete nested transceiver antenna model (corresponding to...). Figure 1 d). Perform multi-parameter collaborative iterative optimization on the model. The optimization process is as follows: Figure 3 As shown. After multiple rounds of adjustments, the antenna achieved optimal matching performance at the target frequency (24.01 GHz), with a reflection coefficient as low as -64.001 dB and excellent impedance matching characteristics. When the chamfer was within the range of 0.1 mm to 0.3 mm, the reflection coefficient fluctuated only slightly (≤3 dB). When the chamfer was less than 0.1 mm or greater than 0.3 mm, edge scattering increased, and the reflection coefficient deteriorated to below -35 dB.

[0093] Full-wave simulation was performed on the optimized antenna to evaluate its radiation characteristics. Figure 4 The three-dimensional radiation pattern shows that the antenna has a maximum gain of 11.028 dBi, good pattern symmetry, and no obvious sidelobe interference. Figure 5Comparing the radiation patterns of the transmitting and receiving antennas in polar coordinates reveals that the multi-sector transmitting beam has a wide coverage range (approximately 240°), while the receiving beam covers the main signal directions (0°~32° and 328°~360°). The measured half-power angle coverage of the transmitting beam is 227°. The high overlap between the receiving and transmitting beams is 0°~31° and 323°~357°, with a power coupling efficiency of 88% and an axial ratio fluctuation of ≤0.6 dB. This high overlap with the transmitting and receiving beams is not exclusive to the four-element sector probe antenna; other multi-sector structures with N≥4 can also achieve this through symmetry parameter optimization, effectively improving signal reception efficiency and suppressing interference from non-target directions. Figure 6 The axial ratio curves show that the antenna has an axial ratio of less than 3 dB in the target frequency range of ±1 GHz (23.74 GHz~24.23 GHz), exhibiting excellent circular polarization performance and suitable for measurement scenarios with high polarization purity requirements.

[0094] To highlight the universal advantages of this invention in terms of miniaturization, Figure 7 The design of this embodiment (d, N=4) is compared in size with three typical loop antenna structures in the literature (high-efficiency electrically small loop antenna a, multi-loop antenna b, and coplanar feed antenna c). It is readily apparent that the radial dimension (R=9mm) of the antenna of this invention is significantly smaller than the comparative antenna, reducing it by more than 65% compared to similar designs. This miniaturization advantage stems from the combined design of multi-sector truncation and nested layout, and is not limited by the specific value of N (N≥4). All multi-sector nested antennas conforming to the structural logic of this invention can achieve the same degree of size optimization.

[0095] Example 2

[0096] This embodiment uses N=4 as an example for detailed explanation. Its core design principles are: mode suppression, nested layout, and parameter co-optimization. It is applicable to all even-numbered sector structures with N≥4, but specific size parameters and performance indicators need to be re-optimized according to the N value. The data in the following embodiment are only for the specific implementation with N=4 and do not constitute a limitation on other N values. Through parameter sweep simulation, the multi-sector antenna (using...) is analyzed... For example, the rules apply to all cases where N≥4) and the impact of key size parameters on performance provide a general adjustment basis for antenna design with different numbers of sectors.

[0097] Cut-off width It is the core parameter that determines the electromagnetic coupling strength between multi-sector radiation units, and its influence is consistent for all multi-sector structures with N≥4. Figure 8 Showing When the antenna transmitter changes The changes. When When N = 0.96 mm (the optimal value in this embodiment; different values ​​of N can be adjusted within the range of 0.5 mm to 2 mm), the antenna matching is optimal (-64.001 dB@24.01 GHz). Slight deviations from this optimal value will lead to a sharp degradation in performance, indicating that this parameter is highly sensitive and needs to be adjusted according to the number of sectors. Precise control is required to ensure effective modal suppression.

[0098] Grounding plate dimensions It affects the coupling characteristics between the antenna and the ground plane, and its influence trend is universal. Figure 9 The display shows that, with Increasing the diameter from 8.8 mm to 9.2 mm (different N values ​​can be adapted within the range of 6 mm to 12 mm), the antenna matching performance was initially optimized and then deteriorated. The optimal value is achieved when the diameter is 9 mm (the optimal value in this embodiment). This parameter mainly affects the matching of the transmitter, while the receiver is less sensitive to it. When adjusting it, the performance of the transmitter should be prioritized.

[0099] Average ring width of the sector ( , To cut off the outer radius of the emitted radiation in multiple sectors, The inner radius mainly affects the resonance characteristics of the radiating element itself, and its stability advantage is applicable to all multi-sector structures with N≥4. Figure 10 Display, change (In this embodiment, the value range is 1.64 mm-2.04 mm, and different N values ​​can be adjusted within the corresponding ratio range.) It has a very small impact on the resonant frequency of the transmitter, with only slight variations between 23.98 GHz and 24.09 GHz, which proves the frequency stability of the multi-sector symmetrical structure (N≥4) and that the performance of the target frequency band can be maintained without frequent adjustments.

[0100] The center probe receives the antenna radius. It is a core parameter that determines the performance of the receiving antenna. Its influence is not limited by the number of sectors N. Figure 11 show, Variations in N (in this embodiment, the value ranges from 4.00 mm to 4.40 mm; different values ​​of N can be adapted within the range of 3 mm to 6 mm) will cause a significant drift in the resonant frequency of the receiver (the maximum offset exceeds 2 GHz). It is the primary parameter for tuning the receiving antenna and needs to be precisely matched according to the target frequency.

[0101] Example 3

[0102] This embodiment uses N=4 as an example for detailed explanation. Its core design principles are: mode suppression, nested layout, and parameter collaborative optimization. It is applicable to all even-numbered sector structures with N≥4, but specific size parameters and performance indicators need to be re-optimized according to the N value. The data in the following embodiment are only for the specific implementation of N=4 and do not constitute a limitation on other N values. (For a four-element sector probe antenna...) The physical processing and performance testing were carried out, and the deviation between the actual test and the simulation was analyzed to verify the universality and robustness of the design of this invention. This verification logic is applicable to all multi-sector nested antennas with N≥4.

[0103] This embodiment is based on the optimized parameters determined in Embodiment 1 ( The preferred combination at that time, other N can be adapted within the corresponding range of parameters), using silicon dioxide with 0.08 mm ( Actual sample of RO 4350B sheet material with anti-reflective coating, as shown in the image. Figure 12 As shown, Table 1 is Preferred size parameters for multi-sector nested antennas:

[0104] ;

[0105] The physical device was tested using a Keysight N5247B PNA-X vector network analyzer, and the measured results were compared with the simulation results. Figure 13 As shown in the figure, the optimal operating frequency of the transmitting antenna is 24.14 GHz, with a reflection coefficient of -42.807 dB and an absolute bandwidth of 0.027 GHz; the reflection coefficient of the receiving antenna is -49.594 dB, with an absolute bandwidth of 0.164 GHz. Although there is an offset of about 0.13 GHz from the simulated frequency, the curve shape and performance trend are highly consistent, and the measured relative bandwidth is much less than 1%, meeting the requirements for narrowband high-precision measurement and verifying the feasibility of the design of this invention.

[0106] A sensitivity analysis was conducted to investigate the cause of the measured and simulated frequency shift (0.13 GHz). The conclusions are applicable to all multi-sector nested antennas with N≥4.

[0107] a. Influence of machining and assembly errors: Figure 14 The effect of the change in the radius of the dielectric layer (representing the machining and assembly error) was simulated. The simulation showed that when this dimension fluctuates within ±0.05 mm, it will cause a frequency offset of about ±0.15 GHz. The measured offset falls within this range.

[0108] b. Influence of dielectric material parameter deviations: Figure 15 The simulation showed that the dielectric constant tolerance (3.61-3.71) of the medium caused systematic frequency and gain drift, which is a normal phenomenon caused by the inherent tolerance of the material.

[0109] The above embodiments are for illustrative purposes only. For example, several specific implementations of this application are illustrated, and their descriptions are quite specific and detailed, but this does not limit the scope of protection of this application. For those skilled in the art, any modifications and improvements made to the number of sectors N (N≥4), specific size parameters, media materials, etc., without departing from the core concept of this application (multi-sector truncated structure + nested receiver / distributor layout + modal suppression principle), are all within the scope of protection of this application. Therefore, the scope of protection of this patent application should be determined by the appended claims.

Claims

1. A ring probe nested transceiver antenna for short-range measurement, characterized in that, The antenna includes a multi-sector truncated radiating element, a central probe receiving antenna, a feeding structure, a dielectric substrate, and a ground plane; the multi-sector truncated radiating element consists of N identical sector-shaped conductor units arranged symmetrically around an Nth rotational symmetry group, used to transmit microwave signals; The central probe receiving antenna is nested in the central region of the multi-sector truncated radiating element and is used to receive the echo signal reflected by the target, realizing the integrated transceiver function; the feeding structure is connected to the multi-sector truncated radiating element and the central probe receiving antenna respectively and is used to provide feeding excitation; the multi-sector truncated radiating element and the central probe receiving antenna are both disposed on a dielectric substrate, and a metal ground plane is disposed at the bottom of the dielectric substrate.

2. The ring probe nested transceiver antenna according to claim 1, characterized in that, The multi-sector truncated radiator is designed based on an N-order rotational symmetry group, where N ≥ 4 and N is an even number, and is a truncated structure. The effective electrical length of each sector unit is 1 / N of the corresponding complete ring structure. Each sector unit has an arc-shaped chamfered structure on its radial edge, and there are certain gaps between the sector units. Through the synergistic effect of the N-order rotational symmetry layout and the equal-spaced offset of the feed phase, the offset is... / This causes the phases of non-target order currents to be opposite in pairs, achieving higher-order resonant mode suppression through spatial electromagnetic superposition and cancellation: the current distribution of higher-order modes forms opposite phases in symmetrical sector units, and mode suppression is achieved through spatial superposition and cancellation of electromagnetic radiation, retaining only a single resonance of the target order, ensuring the purity of the signal spectrum, and its feed phase relationship satisfies: ； in, Indicates the first Current distribution in a sector-shaped conductor unit, =0,1,2…N; for The current distribution on the ring is in the first-order mode. The combined current on the multi-sector cutoff radiating body is: ； The combined current of the multi-sector truncated radiating body satisfies the following expression: ； In the formula For the combined current, The order of the pattern. The phase angle, It is a positive integer; The multi-sector truncated radiating element, through its symmetrical structure and phase relationship, suppresses the inherent high-order electromagnetic resonance modes of the loop antenna, so that the antenna generates a single main resonance response only within the target frequency band.

3. The ring probe nested transceiver antenna according to claim 2, characterized in that, The target frequency band is the millimeter wave band of 18 GHz to 30 GHz, and the target frequency point is any frequency point within the band.

4. The ring probe nested transceiver antenna according to claim 1, characterized in that, The nested arrangement ensures that the transmitting beam of the multi-sector truncated transmitting radiator and the receiving beam of the central probe receiving antenna highly overlap within a preset angle range, achieving directional transmission and reception and multipath interference suppression. The half-power angle coverage range of the transmitting beam is 180°~270°, and the receiving beam forms a high overlap region of 20°~60° in the main lobe region of the transmitting beam. The power coupling efficiency in the overlap region is ≥85%, and the axial ratio fluctuation in the overlap region is ≤1 dB.

5. The ring probe nested transceiver antenna according to claim 1, characterized in that, The antenna satisfies at least one of the following structural parameter relationships: The radius of the central probe receiving antenna The diameter is 3 mm to 6 mm; The multi-sector truncated outer radius of the emitting radiator The inner radius is 4 mm to 10 mm. The diameter is 3 mm to 6 mm; The cutoff width between the multi-sector truncated radiator and the central probe receiving antenna It ranges from 0.5 mm to 2 mm; The dimensions of the metal ground plate The diameter is 8 mm to 12 mm; The thickness of the dielectric substrate It ranges from 0.3 mm to 1 mm; The distance between the feed point and the center of the multi-sector radiating element The diameter is 3 mm to 8 mm; The distance between the feed point of the central probe receiving antenna and the center The thickness is 1 mm to 3 mm. The above range is a general adaptation range for the number of sectors N≥4 (even number). Different N values ​​need to be adjusted specifically within this range.

6. The ring probe nested transceiver antenna according to claim 5, characterized in that, It also includes parameter combinations optimized based on simulation and experimental results with N=4, resulting in a quaternary sector structure; specific parameters are as follows: The radius of the central probe receiving antenna It is 4.32 mm; The multi-sector cutoff radiating body ( outer radius It is 8.28 mm, inner radius It is 4.86 mm; The cutoff width between the multi-sector radiating element and the central probe receiving antenna It is 0.96 mm; The dimensions of the metal ground plate It is 9 mm; The thickness of the dielectric substrate It is 0.508 mm; The location of the multi-sector emitting radiator metal probe It is 5.22 mm; The position of the center probe receiving antenna metal probe It is 2.44 mm; When the number of sectors N is 6, 8, or an even number ≥ 4, multi-parameter collaborative optimization needs to be performed again to ensure that the antenna mode suppression effect matches the transmit and receive performance.

7. The ring probe nested transceiver antenna according to claim 1, characterized in that, The antenna has a reflection coefficient ≤ -40 dB and a reflection coefficient fluctuation ≤ 5 dB within the target frequency range of ±0.5 GHz; the relative bandwidth is 0.1%~0.5% and the gain fluctuation within the bandwidth is ≤ 0.8 dBi. The absolute bandwidth of the antenna in the target frequency band is ≤0.2 GHz; The antenna has a maximum radiation gain of ≥8 dBi at the target frequency. The antenna has an axial ratio of less than 3 dB within the target frequency range of ±1 GHz and possesses circularly polarized radiation characteristics.

8. The ring probe nested transceiver antenna according to claim 1, characterized in that, The dielectric substrate is a high-frequency board with a dielectric constant of 2.2~4.4 and a dielectric loss tangent of ≤0.004 (@10GHz), and the upper surface of the dielectric substrate is provided with an anti-reflection coating with a thickness of 0.05 mm~0.1 mm.

9. The ring probe nested transceiver antenna according to claim 1 as described in claim 8, characterized in that, Magnesium fluoride is used for the anti-reflective coating. Silica It can be made of one or more of polytetrafluoroethylene (PTFE), with a coating thickness of 0.05 mm to 0.1 mm, a dielectric loss tangent of ≤0.001 (@10 GHz to 30 GHz), and an adhesion to the dielectric substrate of ≥5 N / cm², effectively reducing electromagnetic reflection loss in the millimeter wave band.

10. A short-range microwave measurement system, characterized in that, The device includes a ring probe nested transceiver antenna as described in any one of claims 1-9, wherein the ring probe nested transceiver antenna is used to transmit microwave detection signals and receive echo signals from the object under test, thereby achieving close-range measurement of the object under test through the interaction of the detection signals and echo signals.

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