An ultrawideband microwave liver detection system and method based on metasurface
By combining an ultra-wideband patch antenna and a metasurface array, the problem of low gain in existing microwave fatty liver detection devices has been solved, achieving high-precision non-invasive fatty liver detection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XIAN UNIV OF TECH
- Filing Date
- 2026-05-06
- Publication Date
- 2026-06-05
AI Technical Summary
Existing microwave fatty liver detection devices are large in size, expensive, and have low gain, making it difficult to capture weak echo signals from deep liver tissue, resulting in insufficient detection accuracy.
A combination of an ultra-wideband patch antenna and a metasurface array is used. The metasurface array reflects and reconstructs the microwave signal to improve the gain, while the ultra-wideband patch antenna receives the reflected echo signal for signal feature extraction.
The antenna gain was significantly improved, enabling the reception of reflected echo signals from deeper tissues with higher signal-to-noise ratios, thus improving detection accuracy.
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Figure CN122140222A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of ultra-wideband microwave technology, and in particular to an ultra-wideband microwave liver detection system and method based on metasurface. Background Technology
[0002] Microwave detection technology is considered a promising non-invasive detection method due to its sensitivity to the water content and dielectric properties of biological tissues, as well as its potential for safety and low cost. However, existing microwave fatty liver detection devices are very limited and employ multi-antenna array structures, resulting in large device size, high cost, and complex wearable setup. Furthermore, the small-volume ultra-wideband patch antennas attached to the abdomen typically have low gain, leading to poor focusing of ultra-wideband microwave signals. This results in insufficient transmission energy and reception sensitivity, making it difficult to capture weak echo signals from deep liver tissue, thus causing insufficient detection accuracy. Therefore, improving antenna echo gain is crucial for microwave detection of fatty liver. Developing a microwave fatty liver detection device that overcomes the limitations of existing technologies and combines the advantages of accuracy, convenience, non-invasiveness, and low cost has significant clinical value and industrialization prospects. Summary of the Invention
[0003] The purpose of this application is to provide an ultrawideband microwave liver detection system and method based on metasurfaces, which can effectively detect fatty liver using non-invasive microwave technology.
[0004] To achieve the above objectives, this application provides the following solution: In a first aspect, this application provides an ultra-wideband microwave liver detection system based on metasurfaces, comprising: an ultra-wideband patch antenna, a metasurface array, and a signal processing module. The ultra-wideband patch antenna is attached to the liver on the abdominal surface of a human body, emitting a first ultra-wideband microwave signal forward towards the liver and simultaneously radiating a second ultra-wideband microwave signal backward. The metasurface array is arranged parallel to the rear of the ultra-wideband patch antenna and is insulated and fixed to the ultra-wideband patch antenna at a preset spacing. The metasurface array includes multiple metasurface units. The metasurface array is used to reflect the second ultra-wideband microwave signal and reconstruct a third ultra-wideband microwave signal propagating forward towards the liver. The signal processing module is electrically connected to the ultra-wideband patch antenna and is used to extract signal features based on the reflected echo signal received by the ultra-wideband patch antenna to obtain liver detection results. The reflected echo signal is formed by the reflection of the first ultra-wideband microwave signal and the third ultra-wideband microwave signal at the liver. The liver detection results include healthy liver and fatty liver.
[0005] In one embodiment, the metasurface unit includes: a first dielectric substrate, a first metal patch layer, and a second metal patch layer. The first metal patch layer is disposed on the front side of the first dielectric substrate and includes an edge metal crack ring concentric with the first dielectric substrate, a cross metal strip located at the center of the first dielectric substrate, and four metal blocks located between the edge metal crack ring and the cross metal strip. The second metal patch layer is disposed on the back side of the first dielectric substrate and is the same size as the first dielectric substrate.
[0006] In one embodiment, the edge metal crack ring has a crack at the center of its top end.
[0007] In one embodiment, the metal material of both the first metal patch layer and the second metal patch layer is copper.
[0008] In one embodiment, the first dielectric substrate is made of FR4 material.
[0009] In one embodiment, the metasurface array is composed of 5×5 metasurface units.
[0010] In one embodiment, the preset spacing is set to 10mm-20mm.
[0011] In one embodiment, the ultra-wideband patch antenna includes: a second dielectric substrate and a third metal patch layer, wherein the third metal patch layer is disposed on the front side of the second dielectric substrate; the third metal patch layer has a U-shaped slot and includes a peripheral grounding region and a central radiating patch region.
[0012] Secondly, this application provides a metasurface-based ultrawideband microwave liver detection method, comprising: attaching an ultrawideband patch antenna to the liver on the abdominal surface of a human body, with a metasurface array arranged parallel to the rear of the ultrawideband patch antenna and fixed insulated from the ultrawideband patch antenna at a preset distance; using the ultrawideband patch antenna to transmit a first ultrawideband microwave signal forward to the liver, and simultaneously radiating a second ultrawideband microwave signal backward; the metasurface array reflecting the second ultrawideband microwave signal and reconstructing a third ultrawideband microwave signal propagating forward to the liver; the ultrawideband patch antenna receiving the reflected echo signal; the reflected echo signal being formed by the reflection of the first ultrawideband microwave signal and the third ultrawideband microwave signal at the liver; and a signal processing module performing signal feature extraction based on the reflected echo signal received by the ultrawideband patch antenna to obtain liver detection results; the liver detection results including healthy liver and fatty liver.
[0013] In one embodiment, the liver detection result is obtained by extracting signal features based on the reflected echo signal received by the ultra-wideband patch antenna. Specifically, this includes: extracting the amplitude features of peaks and troughs within a preset feature time window based on the reflected echo signal received by the ultra-wideband patch antenna; and obtaining the liver detection result by comparing the amplitude features with a preset feature threshold for a healthy liver.
[0014] According to the specific embodiments provided in this application, the following technical effects are disclosed: This application provides an ultra-wideband microwave liver detection system and method based on metasurfaces. The system employs an ultra-wideband patch antenna to radiate a first ultra-wideband microwave signal forward (towards the liver) to penetrate human tissue, and a second ultra-wideband microwave signal to radiate backward (away from the body). A metasurface array, arranged parallel to the rear of the ultra-wideband patch antenna, reflects the second ultra-wideband microwave signal and reconstructs a third ultra-wideband microwave signal propagating forward towards the liver. This refocuses the third ultra-wideband microwave signal forward (towards the liver), significantly improving the gain of the ultra-wideband patch antenna. Due to the gain enhancement effect of the metasurface, the liver generates stronger microwave scattering and energy oscillations, enabling the antenna to receive reflected echo signals from deeper tissues with higher signal-to-noise ratios. This allows for signal feature extraction, obtaining liver detection results and improving detection accuracy. Attached Figure Description
[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0016] Figure 1 This is a schematic diagram of the structure of an ultra-wideband patch antenna and a metasurface array provided in an embodiment of this application.
[0017] Figure 2 This is a perspective view of an ultra-wideband patch antenna provided in an embodiment of this application.
[0018] Figure 3 This is a front view of an ultra-wideband patch antenna provided in an embodiment of this application.
[0019] Figure 4 This is a schematic diagram of the structure of a metasurface unit provided in an embodiment of this application from a first-view perspective.
[0020] Figure 5 This is a schematic diagram of the metasurface unit provided in an embodiment of this application from a second perspective.
[0021] Figure 6 This is a schematic diagram showing the dimensions of a metasurface unit provided in an embodiment of this application.
[0022] Figure 7 This is a side view of an ultra-wideband patch antenna, a metasurface array, and the human abdominal surface, provided in an embodiment of this application.
[0023] Figure 8 This is a top view of an ultra-wideband patch antenna, a metasurface array, and the human abdominal surface, provided in an embodiment of this application.
[0024] Figure 9 Antenna gain curves of unloaded metasurface array and loaded metasurface array provided in an embodiment of this application.
[0025] Figure 10 This is a schematic diagram of the reflected echo signals of an ultra-wideband patch antenna for a healthy liver and fatty liver, provided in an embodiment of this application. Figure 10 (a) in the figure represents the local amplification state of the reflected echo signal.
[0026] Figure 11 This is a flowchart of an ultrawideband microwave liver detection method based on metasurfaces provided in an embodiment of this application.
[0027] Figure label: 1-Ultra-wideband patch antenna; 10-Second dielectric substrate; 110-U-shaped slot; 111-Outer grounding area; 112-Central radiating patch area; 2-Metasurface array; 20-First dielectric substrate; 211-Edge metal crack ring; 212-Cross metal strip; 213-Metal block; 22-Second metal patch layer; 3-Abdomen; 4-Liver. Detailed Implementation
[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0029] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0030] Fatty liver disease is a common metabolic liver disease with insidious onset and no obvious specific symptoms in the early stages. If it is not accurately detected and intervened for a long time, it can easily progress to fatty hepatitis, cirrhosis, and even liver cancer, seriously threatening human health. Early screening for fatty liver is crucial for preventing the progression of liver disease. Currently, liver biopsy is the gold standard for diagnosis, but it is invasive. Imaging methods (such as ultrasound and CT scans), although non-invasive, are expensive, rely on the operator's experience, have limited sensitivity to early steatosis, and are time-consuming, making them difficult to popularize in primary care / community healthcare institutions.
[0031] This application provides an ultrawideband microwave liver detection system based on metasurfaces, including: an ultrawideband patch antenna 1, a metasurface array 2, and a signal processing module.
[0032] like Figure 1 As shown, the ultra-wideband patch antenna 1 is attached to the liver on the abdominal surface of the human body, emitting a first ultra-wideband microwave signal forward to the liver 4 and simultaneously radiating a second ultra-wideband microwave signal backward. The metasurface array 2 is arranged parallel to the rear of the ultra-wideband patch antenna 1 and is insulated and fixed to the ultra-wideband patch antenna 1 at a preset interval. The metasurface array 2 includes multiple metasurface units; the metasurface array 2 is used to reflect the second ultra-wideband microwave signal and reconstruct a third ultra-wideband microwave signal propagating forward to the liver 4. The signal processing module is electrically connected to the ultra-wideband patch antenna 1 and is used to extract signal features based on the reflected echo signal received by the ultra-wideband patch antenna 1 to obtain the liver detection result; the reflected echo signal is formed by the reflection of the first and third ultra-wideband microwave signals at the liver; the liver detection result includes healthy liver and fatty liver.
[0033] This application employs an ultra-wideband patch antenna 1 to radiate a first ultra-wideband microwave signal forward (towards the liver) to penetrate human tissue, and a second ultra-wideband microwave signal to radiate backward (away from the human body). A metasurface array 2, arranged parallel to the rear of the ultra-wideband patch antenna 1, reflects the second ultra-wideband microwave signal and reconstructs a third ultra-wideband microwave signal propagating forward toward the liver 4, thereby refocusing the third ultra-wideband microwave signal forward (towards the liver) and significantly improving the gain of the ultra-wideband patch antenna 1. Due to the gain enhancement effect of the metasurface, the liver 4 generates stronger scattering and energy oscillation of microwaves, and the antenna can receive reflected echo signals from deeper tissues with higher signal-to-noise ratios, thereby extracting signal features, obtaining liver detection results, and improving detection accuracy.
[0034] In another exemplary embodiment of this application, the metasurface unit includes: a first dielectric substrate 20, a first metal patch layer, and a second metal patch layer 22. The first metal patch layer is disposed on the front side of the first dielectric substrate 20, and includes an edge metal crack ring 211 concentric with the first dielectric substrate 20, a cross metal strip 212 located at the center of the first dielectric substrate 20, and four metal blocks 213 located between the edge metal crack ring 211 and the cross metal strip 212; the second metal patch layer 22 is disposed on the back side of the first dielectric substrate 20 and is the same size as the first dielectric substrate 20.
[0035] In another exemplary embodiment of this application, the edge metal crack ring 211 has a crack at the center of its top end.
[0036] In another exemplary embodiment of this application, the metal material of both the first metal patch layer and the second metal patch layer 22 is copper.
[0037] In another exemplary embodiment of this application, the first dielectric substrate 20 is made of FR4 material.
[0038] In another exemplary embodiment of this application, the metasurface array 2 is composed of 5×5 metasurface units.
[0039] In another exemplary embodiment of this application, the preset spacing is set to 10mm-20mm.
[0040] In another exemplary embodiment of this application, the ultra-wideband patch antenna 1 includes: a second dielectric substrate 10 and a third metal patch layer, the third metal patch layer being disposed on the front side of the second dielectric substrate 10; the third metal patch layer has a U-shaped slot 110, and the third metal patch layer includes a peripheral grounding region 111 and a central radiating patch region 112. Figures 2-3 As shown, the ultra-wideband patch antenna 1 has a slotted grounding structure and its dimensions are 15mm. 15mm 1.6mm. This ultra-wideband patch antenna 1 consists of a second dielectric substrate 10 and a third metal patch layer. The third metal patch layer is disposed on one surface of the second dielectric substrate 10, while the other surface is uncovered with metal. The material of the second dielectric substrate 10 is FR-4, and the material of the third metal patch layer is annealed copper. A U-shaped slot 110 is formed on the third metal patch layer, dividing it into an outer grounding region 111 and a central radiating patch region 112. The central radiating patch region 112 includes a rectangular body and a stepped feed port at the bottom. An ultra-wideband narrow pulse excitation source is fed in through this feed port. The stepped shape changes the current path on the surface of the metal layer, exciting multiple resonant modes and realizing ultra-wideband microwave signal radiation.
[0041] Specifically, the design scheme of this application is as follows: 1) Initially construct a square first dielectric substrate 20 and design a square metal crack ring (i.e., edge metal crack ring 211).
[0042] 2) Design a cross-shaped copper strip (i.e., cross metal strip 212) located in the center and a square copper sheet (i.e., metal block 213) between the cross copper strip and the crack ring.
[0043] 3) Arrange the metamaterial units and place them behind the miniaturized ultrawideband patch antenna 1.
[0044] 4) The specific structural parameters of the ultra-wideband patch antenna 1 and the metasurface array 2 were determined through simulation, and the gain variation of the ultra-wideband patch antenna 1 was analyzed.
[0045] 5) For the human body to be tested, the reflected echo signal received by the ultra-wideband patch antenna 1 is measured, and the characteristic time window is determined by theoretical derivation. The condition of the liver is judged based on the signal characteristic pattern within the window.
[0046] The following describes the specific implementation method of the ultrawideband microwave liver detection system based on metasurfaces in this application. The specific steps are as follows.
[0047] Step 1: Construct the first dielectric substrate 20 on the metamaterial unit. The first dielectric substrate 20 is designed to be square, and the constituent material of the square first dielectric substrate 20 is FR4. The metal material on the square first dielectric substrate 20 is annealed copper. The dielectric constant of FR4 is 4.3, the loss tangent is 0.025, the thickness is 2.4 mm, and the side length of the first dielectric substrate 20 is r6 = 7 mm.
[0048] Step 2: Construct the first metal patch layer and the second metal patch layer 22 on the metamaterial unit, as follows: Figures 4-5 As shown.
[0049] A first metal patch layer is designed on the front side of the first dielectric substrate 20, and a second metal patch layer 22 is covered on the back side, as detailed below. Figures 2-3 As shown, a square metal ring (i.e., edge metal ring 211) concentric with the square first dielectric substrate 20 is first printed. The ring width r1 = 0.75 mm, the ring side length r9 = 6 mm, the ring crack r4 = 0.75 mm, and the distance from the edge of the dielectric substrate r7 = 0.5 mm. This square metal ring structure located on the outer layer mainly functions to excite specific magnetic resonance modes and generate effective local field enhancement for incident electromagnetic waves, ensuring that energy can reach the liver region and return.
[0050] A concentric cross-shaped copper strip (i.e., cross metal strip 212) composed of horizontal and vertical copper strips is arranged at the center of the first dielectric substrate 20. The width of the copper strip is r3 = 0.4 mm, and the length of the copper strip is r8 = 3 mm. The central area is evenly divided into four quadrants. Four symmetrically distributed square copper sheets (i.e., metal blocks 213) are arranged in the four divided quadrants respectively. The side length of the square copper sheet is r2 = 1 mm, and the distance between the square copper sheet and the square metal split ring is r5 = 0.625 mm. A first metal patch layer with a symmetric "hui" - shaped metal pattern is formed on the front surface of the first dielectric substrate 20, which can excite multiple resonance modes and maintain the working bandwidth of the unit.
[0051] As Figure 6 shown, it is a schematic diagram of the dimension marking of the metasurface unit. Among them, the width of the square metal split ring is r1, the side length of the internal square copper sheet is r2, the width of the central cross copper strip is r3, the ring crack (or the crack length of the square metal split ring) is r4, the distance between the square copper sheet and the square metal split ring is r5, the side length of the first dielectric substrate 20 is r6, the distance between the square metal split ring and the first dielectric substrate 20 is r7, the length of the cross copper strip is r8, and the side length of the square metal split ring is r9.
[0052] Step 3: Arrange the metamaterial units in a 5×5 layout to form a metasurface array 2. The metasurface array 2 is densely arranged with 25 metamaterial units. Attach a single miniaturized ultra - wideband patch antenna 1 to the front body surface (near the liver side) of the measured human abdomen 3, place the metasurface array 2 10 mm behind the ultra - wideband patch antenna 1 (if the distance is too large, it only acts as a reflector; if the distance is too small, the coupling is too strong and the original matching of the antenna is damaged), and keep the planes of the two parallel, as Figure 1 shown.
[0053] Step 4: According to the current designed crack and side length dimensions of the square metal split ring, the size of the square copper sheet in the four quadrants, the length of the cross copper strip in the center, the number of metasurface units, and the distance between the antenna and the metasurface, it can effectively reflect and reconstruct the energy of the antenna's backward radiation, making it refocus forward (towards the liver direction), thereby significantly enhancing the gain of the antenna. This enhancement effect is beneficial for obtaining a higher signal - to - noise ratio and deeper tissue reflection echoes in liver detection.
[0054] When the metasurface array 2 is not loaded, a part of the energy of the ultra - wideband patch antenna 1 radiates forward (towards the liver direction) for penetrating human tissues, and another part of the energy radiates backward (away from the human body direction), resulting in serious deficiencies in transmission energy and reception sensitivity. By loading the metasurface array 2 at the backward position of the ultra - wideband patch antenna 1, the electromagnetic waves radiated backward by the antenna are incident on the metasurface array 2, and the designed metasurface array 2 will generate multi - resonance mode coupling, thereby enhancing the gain in a wide frequency band.
[0055] The specific principle is as follows: (1) First, determine the resonant mode of the square metal split ring, and calculate the equivalent inductance of the square metal split ring according to the formula. The equivalent inductance of the square metal crack ring is obtained. Approximately 45.9 nH, of which, The permeability of free space, Let be the equivalent perimeter of the ring. This is the opening correction factor. The equivalent capacitance at the opening (or crack) of the square metal crack ring is calculated according to the formula... The calculation yielded that, The vacuum permittivity, It is the equivalent dielectric constant. , , Let be the modulus of the elliptic integral. for The complement of the modulus, This is a first-kind elliptic integral, thus calculating... It is approximately 27.9fF. Therefore, according to the formula... The calculated resonant point produced by this cracked ring is approximately 4.5 GHz.
[0056] The square metal split ring is an open-ring resonant structure. Its magnetic resonance excitation principle is as follows: when an electromagnetic wave is incident, the magnetic field component passes perpendicularly through the ring region enclosed by the split ring. According to Faraday's law of electromagnetic induction, the changing magnetic field induces a ring-shaped circulating current in the metal ring. The metal ring portion of the split ring is equivalent to an inductor L, and the gap in the ring is equivalent to a capacitor C. Together, they form an LC resonant circuit, thereby exciting a magnetic resonance mode at a specific frequency. This magnetic resonance can enable the metasurface unit to produce strong electromagnetic localization field enhancement and high reflection characteristics.
[0057] (2) For the cross-shaped copper strip and the square copper sheet, the cross-shaped copper strip consists of two orthogonal slender conductors, each with an arm length of r8. The inductance of the cross-shaped copper strip is calculated using the formula... The equivalent inductance produced can be obtained. Approximately 4.08 nH, of which, The permeability of free space is given by the formula for approximating the equivalent capacitance between the four square copper sheets and the square metal ring. Calculations yielded Approximately 42.1 fF, of which, The vacuum permittivity, It is the equivalent dielectric constant. , , Let be the modulus of the elliptic integral. for The complement of the modulus, For a complete elliptic integral of the first kind, the equivalent capacitance of four square copper sheets is... Approximately 168.4 fF. Similarly, the capacitance between the end of the cross-shaped copper strip and the square metal ring is calculated using the formula... The calculated equivalent capacitance at each end is approximately 13.2 fF, where, The vacuum permittivity, It is the equivalent dielectric constant. , , Let be the modulus of the elliptic integral. for The complement of the modulus, For a first-type complete elliptic integral, the equivalent capacitance at the ends of the four copper bars is... It is 52.8fF. Total equivalent capacitance. fF. Therefore, the overall structure composed of the cross-shaped copper strip and the square copper sheet has a resonant point. It is approximately 5.3 GHz.
[0058] The linear structure of the central cross-shaped copper strip and the square copper sheet excite the secondary electrical resonance. Different sizes and shapes of electrical structures (metal strips or patches) will produce different resonance points, which can extend the operating bandwidth. Multi-mode resonance (magnetic resonance + secondary resonance) ensures high reflectivity throughout the ultra-wideband frequency band. Secondly, by arranging metasurface units to form a metasurface array 2, the backward radiation wave is controlled globally, so that the electromagnetic waves reflected by each unit are coherently superimposed in phase in the liver direction, achieving a significant enhancement of beam focusing and radiation gain.
[0059] The metasurface element of this application exhibits two adjacent resonant modes near 4.5 GHz (dominated by a square metal cracked ring) and 5.3 GHz (dominated by a cross-shaped copper strip and a square copper sheet). These two modes overlap through electromagnetic coupling within the metasurface element, and the reflection coefficient at the resonant point approaches 1. This ensures that the reflection coefficient amplitude of the metasurface remains at a high level within the 3-6 GHz operating frequency band, effectively improving the antenna's forward gain and thus clearly distinguishing the differences in reflected echo signals between healthy livers and fatty livers.
[0060] Figure 7 This is a side view of the ultra-wideband patch antenna 1, the metasurface array 2, and the human abdominal surface. Figure 8 This is a top view of the ultra-wideband patch antenna 1, the metasurface array 2, and the human abdominal surface. Figure 9 The gain curves of the ultra-wideband patch antenna 1 with and without the metasurface array 2 are shown. It can be seen that the gain of the ultra-wideband patch antenna 1 is increased by 4 dBi after loading the metasurface array 2. This enhancement effect is beneficial for obtaining reflected echoes from deeper tissues with higher signal-to-noise ratio in volume detection, thereby more clearly distinguishing the difference in echo signals between healthy liver and fatty liver.
[0061] Step 5: Measure the reflected echo signals from the livers of patients with fatty liver and healthy livers respectively, ensuring the ultra-wideband patch antenna 1 is consistently attached. The liver condition is determined by defining a characteristic time window and calculating the peaks and troughs within that window. First, the characteristic time window is defined as the distance from the liver to the closest point on the frontal surface of the body. The approximate speed is 20 mm (0.02 m). The propagation speed of the electromagnetic wave to the liver is calculated using the wave velocity equation. ,in, At the speed of light, Given the dielectric constant of human fat, the round-trip time of the echo response of liver 4 to ultra-wideband patch antenna 1 is... ,in, The distance from the liver to the closest point on the front of the body is considered, and a redundancy of approximately 0.3 ns is set to account for inherent delays in the antenna and system. Therefore, a critical response time interval can be set. (e.g., 0.89ns-1.2ns), within this range, the echo signals from patients with fatty liver will exhibit stronger scattering and energy oscillation characteristics, such as... Figure 10 As shown, this range can be used to distinguish echo signals in fatty liver. With a healthy liver The characteristic time window is used to identify the signal interval. peak position and the location of the trough If satisfied and This indicates the presence of fatty liver symptoms, among which, for , This represents the time when the signal first reaches the liver surface, ideally. for +a, This indicates the time it takes for the signal to reach the liver surface, taking into account factors such as delay. 'a' represents the delay time, which can be 0.3. For sampling points within the feature window, The signal amplitude at sampling point i within the feature window. The signal amplitude at sampling point i-1 within the feature window.
[0062] like Figure 11 As shown, this application also provides an ultrawideband microwave liver detection method based on metasurface, including the following steps 201 to 205.
[0063] Step 201: The ultra-wideband patch antenna 1 is attached to the liver on the surface of the human abdomen, and the metasurface array 2 is arranged in parallel behind the ultra-wideband patch antenna 1 and fixed insulated from the ultra-wideband patch antenna 1 at a preset distance.
[0064] Step 202: Use the ultra-wideband patch antenna 1 to transmit a first ultra-wideband microwave signal to the liver 4 in front, and at the same time radiate a second ultra-wideband microwave signal to the rear.
[0065] Step 203: The metasurface array 2 reflects the second ultra-wideband microwave signal and reconstructs the third ultra-wideband microwave signal propagating forward toward the liver 4. Specifically, the metal patterns (i.e., the first metal patch layer) on the surface of the metasurface units in the metasurface array 2 form multi-resonant coupling in the 3-6 GHz ultra-wideband range, and the reflected signals of each unit are phase-synchronized, achieving in-phase and coherent superposition of the reflected waves. The second ultra-wideband microwave signal, which was originally dissipated backward by the antenna, is recovered and converged forward toward the liver 4.
[0066] Step 204: The ultra-wideband patch antenna 1 receives the reflected echo signal; the reflected echo signal is formed by the reflection of the first ultra-wideband microwave signal and the third ultra-wideband microwave signal at the liver.
[0067] Step 205: The signal processing module extracts signal features based on the reflected echo signal received by the ultra-wideband patch antenna 1 to obtain liver detection results; the liver detection results include healthy liver and fatty liver.
[0068] In another exemplary embodiment of this application, signal feature extraction is performed based on the reflected echo signal received by the ultra-wideband patch antenna 1 to obtain liver detection results, including the following steps 301 to 302.
[0069] Step 301: Extract the amplitude characteristics of the peaks and troughs within a preset characteristic time window based on the reflected echo signal received by the ultra-wideband patch antenna 1.
[0070] Step 302: Based on the amplitude characteristics, compare them with the preset characteristic threshold of a healthy liver to obtain the liver detection result.
[0071] This application designs a metasurface structure (metasurface unit or metasurface array 2) with multi-resonance characteristics, and combines an ultra-wideband antenna with a multi-resonance metasurface array 2 for coordinated control, to reflect electromagnetic waves that were originally diverged backward back to the target liver region, thereby significantly improving forward radiation gain and received signal strength and sensitivity.
[0072] Specifically, the outer square cracked ring in the metasurface unit generates a magnetic resonant main structure. The magnetic field passes perpendicularly through the loop, exciting the circulating current and forming the main resonant point of the LC magnetic resonant circuit with high reflection. The linear structure and square block of the central cross copper strip generate secondary electrical resonance. Different sizes and shapes of electrical structures will produce different resonance points, which can extend the operating bandwidth. Multi-mode resonance (magnetic resonance + electrical resonance) ensures high reflectivity throughout the ultra-wideband frequency band. Secondly, by arranging the metasurface units to form a metasurface array 2, the backward radiation wave is controlled globally, so that the electromagnetic waves reflected by each unit are coherently superimposed in phase in the liver direction, achieving a significant enhancement of beam focusing and radiation gain.
[0073] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0074] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.
Claims
1. A broadband microwave liver detection system based on metasurfaces, characterized in that, include: An ultra-wideband patch antenna is used to attach to the liver on the surface of the human abdomen, emitting a first ultra-wideband microwave signal forward to the liver and simultaneously radiating a second ultra-wideband microwave signal backward. A metasurface array is arranged parallel to the rear of an ultra-wideband patch antenna and is insulated and fixed to the ultra-wideband patch antenna at a preset distance. The metasurface array includes multiple metasurface units. The metasurface array is used to reflect a second ultra-wideband microwave signal and reconstruct a third ultra-wideband microwave signal that propagates forward toward the liver. A signal processing module, electrically connected to the ultra-wideband patch antenna, is used to extract signal features based on the reflected echo signal received by the ultra-wideband patch antenna to obtain liver detection results; the reflected echo signal is formed by the reflection of a first ultra-wideband microwave signal and a third ultra-wideband microwave signal at the liver; the liver detection results include healthy liver and fatty liver.
2. The ultrawideband microwave liver detection system based on metasurfaces according to claim 1, characterized in that, The metasurface unit includes: First dielectric substrate; A first metal patch layer is disposed on the front side of a first dielectric substrate. The first metal patch layer includes an edge metal crack ring concentric with the first dielectric substrate, a cross metal strip located at the center of the first dielectric substrate, and four metal blocks located between the edge metal crack ring and the cross metal strip. A second metal patch layer is disposed on the back side of the first dielectric substrate and is the same size as the first dielectric substrate.
3. The ultrawideband microwave liver detection system based on metasurfaces according to claim 2, characterized in that, The edge metal crack ring has a crack at the center of its top.
4. The ultrawideband microwave liver detection system based on metasurfaces according to claim 2, characterized in that, The metal material of both the first metal patch layer and the second metal patch layer is copper.
5. The ultrawideband microwave liver detection system based on metasurfaces according to claim 2, characterized in that, The first dielectric substrate is made of FR4 material.
6. The ultrawideband microwave liver detection system based on metasurfaces according to claim 1, characterized in that, The metasurface array is composed of 5×5 metasurface units.
7. The ultrawideband microwave liver detection system based on metasurfaces according to claim 1, characterized in that, The preset spacing is set to 10mm-20mm.
8. The ultrawideband microwave liver detection system based on metasurfaces according to claim 1, characterized in that, The ultra-wideband patch antenna includes: a second dielectric substrate and a third metal patch layer, wherein the third metal patch layer is disposed on the front side of the second dielectric substrate; the third metal patch layer has a U-shaped slot and includes an outer grounding area and a central radiating patch area.
9. A metasurface-based ultrawideband microwave liver detection method based on the metasurface-based ultrawideband microwave liver detection system according to any one of claims 1 to 8, characterized in that, include: An ultra-wideband patch antenna is attached to the liver on the human abdomen, and a metasurface array is arranged in parallel behind the ultra-wideband patch antenna and fixed insulated from the ultra-wideband patch antenna at a preset interval. The first ultra-wideband microwave signal is emitted forward to the liver using an ultra-wideband patch antenna, while the second ultra-wideband microwave signal is radiated backward. The metasurface array reflects the second ultra-wideband microwave signal and reconstructs the third ultra-wideband microwave signal propagating forward toward the liver; An ultra-wideband patch antenna receives reflected echo signals; the reflected echo signals are formed by reflections of a first ultra-wideband microwave signal and a third ultra-wideband microwave signal at the liver. The signal processing module extracts signal features based on the reflected echo signal received by the ultra-wideband patch antenna to obtain liver detection results; the liver detection results include healthy liver and fatty liver.
10. The ultrawideband microwave liver detection method based on metasurfaces according to claim 9, characterized in that, Based on the reflected echo signal received by the ultra-wideband patch antenna, signal features are extracted to obtain the liver detection results, specifically including: Based on the reflected echo signal received by the ultra-wideband patch antenna, the amplitude characteristics of the peaks and troughs are extracted within a preset characteristic time window. The liver detection results are obtained by comparing the amplitude characteristics with the preset characteristic thresholds of a healthy liver.