Zero-Index Metamaterial Superstrates UWB Antenna for Microwave Imaging Detection

Metamaterials(MTM)can enhance the properties of microwaves and also exceed some limitations of devices used in technical practice.Note that the antenna is the element for realizing a microwave imaging(MWI)system since it is where signal transmission and absorption occur.Ultra-Wideband(UWB)antenna superstrates with MTM elements to ensure the signal transmitted from the antenna reaches the tumor and is absorbed by the same antenna.The lack of conventional head imaging techniques,for instance,Magnetic Resonance Imaging(MRI)and Computerized Tomography(CT)-scan,has been demonstrated in the paper focusing on the point of failure of these techniques for prompt diagnosis and portable systems.Furthermore,the importance ofMWIhas been addressed elaborately to portray its effectiveness and aptness for a primary tumor diagnosis.Other than that,MTM element designs have been discussed thoroughly based on their performances towards the contributions to the better image resolution of MWI with detailed reasonings.This paper proposes the novel design of a Zeroindex Split RingResonator(SRR)MTMelement superstrate with a UWB antenna implemented in MWI systems for detecting tumor.The novel design of the MTM enables the realization of a high gain of a superstrate UWB antenna with the highest gain of 5.70 dB.Besides that,the MTM imitates the conduct of the zeroreflection phase on the resonance frequency,which does not exist.An antenna with an MTM unit is of a 7×4 and 10×5 Zero-index SRR MTM element that acts as a superstrate plane to the antenna.Apart from that,Rogers(RT5880)substrate material is employed to fabricate the designed MTM unit cell,with the following characteristics:0.51mm thickness,the loss tangent of 0.02,as well as the relative permittivity of 2.2,with Computer Simulation Technology(CST)performing the simulation and design.Both MTM unit cells of 7×4 and 10×5 attained 0°with respect to the reflection phase at the 2.70 GHz frequency band.The first design,MTM Antenna Design 1,consists of a 7×4 MTM unit cell that observed a rise of 5.70 dB with a return loss(S11)−20.007 dB at 2.70 GHz frequency.The second design,MTM Antenna Design 2,consists of 10×5 MTM unit cells that recorded a gain of 5.66 dB,having the return loss(S11)−19.734 dB at 2.70 GHz frequency.Comparing these two MTM elements superstrates with the antenna,one can notice that the 7×4 MTM element shape has a low number of the unit cell with high gain and is a better choice than the 10×5 MTM element in realizing MTM element superstrates antenna for MWI.

Nonlinear Properties of an Inhomogeneous Diode Structure in a Strong Microwave Field

Results of experimental investigation of detection (rectification) of high power X-band microwave signal in diodes of various design (semiconductor p-n-junction, point-contact, Schottky, Metal-Isolator-Metal—MIM) are reported. The maximum of the detected direct voltage V vs. power P of microwave signal and subsequent polarity reversal, previously found in MIM diodes in the optical and microwave bands, have found to be characteristic of all investigated diodes as well. After the reversal of polarity, this dependence comes linear, and the sign of the voltage corresponds to thermoEMF. In some diodes, the hysteresis on V(P) was observed. All 5 types of V(P) of MIM diodes (have made from different pairs of metals), reported earlier, were reproduced on same p-n-junction diode by variable external DC bias. These results joined with abnormal frequency cutoff forced to suggest that there is an unknown mechanism for direct flow of charge carriers (and for generate direct current) in the high-frequency electrical field, which differs from the conventional rectification.

An Overview of Active Microwave Imaging for Early Breast Cancer Detection

First,this article reviews the background of microwave imaging for early breast cancer detection,with a focus on active methods.Then active approaches,namely microwave tomography and radar-based microwave imaging,to microwave breast cancer detection are overviewed briefly,where there are recent developments in imaging algorithms as well as antennas,models,phantom and experimental systems.Lastly,we give concluding remarks and future research.In a word,the main objective of this article is to provide an overview of the principles,development,and current research status of these approaches.

Wireless Communication Based on Microwave Photon-Level Detection with Superconducting Devices:Achievable Rate Prediction

Future wireless communication systemembraces physical-layer signal detection with highsensitivity, especially in the microwave photon level.Currently, the receiver primarily adopts the signal detection based on semi-conductor devices for signal detection, while this paper introduces high-sensitivityphoton-level microwave detection based on superconducting structure. We first overview existing works onthe photon-level communication in the optical spectrum as well as the microwave photon-level sensingbased on superconducting structure in both theoreticaland experimental perspectives, including microwavedetection circuit model based on Josephson junction,microwave photon counter based on Josephson junction, and two reconstruction approaches under background noise. In addition, we characterize channelmodeling based on two different microwave photondetection approaches, including the absorption barrierand the dual-path Handury Brown-Twiss (HBT) experiments, and predict the corresponding achievablerates. According to the performance prediction, it isseen that the microwave photon-level signal detectioncan increase the receiver sensitivity compared withthe state-of-the-art standardized communication system with waveform signal reception, with gain over 10dB.

Contour Detection-Based Realistic Finite-Difference-Time-Domain Models for Microwave Breast Cancer Detection

In this paper, a collection of three-dimensional(3D)numerical breast models are developed based on clinical magnetic resonance images(MRIs). A hybrid contour detection method is used to create the contour, and the internal space is filled with different breast tissues, with each corresponding to a specified interval of MRI pixel intensity. The developed models anatomically describe the complex tissue structure and dielectric properties in breasts. Besides, they are compatible with finite-difference-time-domain(FDTD)grid cells. Convolutional perfect matched layer(CPML)is applied in conjunction with FDTD to simulate the open boundary outside the model. In the test phase, microwave breast cancer detection simulations are performed in four models with varying radiographic densities. Then, confocal algorithm is utilized to reconstruct the tumor images. Imaging results show that the tumor voxels can be recognized in every case, with 2 mm location error in two low density cases and 7 mm─8 mm location errors in two high density cases, demonstrating that the MRI-derived models can characterize the individual difference between patients' breasts.

Preliminary research and scheme design of deep underground in situ geo-information detection experiment for Geology in Time

The deep earth,deep sea,and deep space are the main parts of the national“three deep”strategy,which is in the forefront of the strategic deployment clearly defined in China’s 14th Five-Year Plan(2021-2025)and the Long-Range Objectives Through the Year 2035.It is important to reveal the evolutionary process and mechanism of deep tectonics to understand the earth’s past,present and future.The academic con-notation of Geology in Time has been given for the first time,which refers to the multi-field evolution response process of geological bodies at different time and spatial scales caused by geological processes inside and outside the Earth.Based on the deep in situ detection space and the unique geological envi-ronment of China Jinping Underground Laboratory,the scientific issue of the correlation mechanism and law between deep internal time-varying and shallow geological response is given attention.Innovative research and frontier exploration on deep underground in situ geo-information detection experiments for Geology in Time are designed to be carried out,which will have the potential to explore the driving force of Geology in Time,reveal essential laws of deep earth science,and explore innovative technologies in deep underground engineering.

SDH-FCOS:An Efficient Neural Network for Defect Detection in Urban Underground Pipelines

Urban underground pipelines are an important infrastructure in cities,and timely investigation of problems in underground pipelines can help ensure the normal operation of cities.Owing to the growing demand for defect detection in urban underground pipelines,this study developed an improved defect detection method for urban underground pipelines based on fully convolutional one-stage object detector(FCOS),called spatial pyramid pooling-fast(SPPF)feature fusion and dual detection heads based on FCOS(SDH-FCOS)model.This study improved the feature fusion component of the model network based on FCOS,introduced an SPPF network structure behind the last output feature layer of the backbone network,fused the local and global features,added a top-down path to accelerate the circulation of shallowinformation,and enriched the semantic information acquired by shallow features.The ability of the model to detect objects with multiple morphologies was strengthened by introducing dual detection heads.The experimental results using an open dataset of underground pipes show that the proposed SDH-FCOS model can recognize underground pipe defects more accurately;the average accuracy was improved by 2.7% compared with the original FCOS model,reducing the leakage rate to a large extent and achieving real-time detection.Also,our model achieved a good trade-off between accuracy and speed compared with other mainstream methods.This proved the effectiveness of the proposed model.

Large Scale Analysis of Complex Permittivity of Breast Cancer in Microwave Band

To obtain some prior knowledge of breast cancer detection by microwave imaging, we have measured and analyzed the complex permittivity of tissues extracted from over 140 breast cancer surgeries. The relative permittivity and conductivity of tumor at 1.6 GHz were 17.5% and 16.2% higher than those of mammary gland tissue, respectively. In invasive ductal carcinoma of scirrhous type, 8 out of 64 had higher relative permittivity and conductivity of mammary gland than those of tumor. However, when evaluated by the Debye parameter considering the frequency dependence of the tissue, it is rare that ε∞ and Δε of cancer are simultaneously lower than those of mammary gland. The relative permittivity and conductivity of fibroadenoma are almost the same as those of mammary glands. The relative permittivity and conductivity of each tissue showed strong linearity. Microwave imaging requires accurate reconstruction of ε∞ and Δε to distinguish cancer from normal tissue.

Response surface optimization of microwave-assisted extraction for HPLC-fluorescence determination of puerarin and daidzein in Radix Puerariae thomsonii

Microwave-assisted extraction was optimized with response surface methodology for HPLC-fluorescence determination of puerarin and daidzein in Radix Puerariae thomsonii.The optimized extraction procedure was achieved by soaking the sample with 70% methanol（1∶15,v/v）for 30 min,and then microwave irradiation for 11 min at a power of 600 W.Coupling the extraction process with HPLC-fluorescence presented good recovery,satisfactory precision,and good linear relation.Compared with a method from the Chinese Pharmacopoeia,the proposed method enables higher extraction efficiency and more accurate analytical results.It can be of potential value in quality assessment of Radix Puerariae thomsonii medicinal materials.

A broadband integrated microwave photonic mixer based on balanced photodetection

An integrated microwave photonic mixer based on silicon photonic platforms is proposed,which consist of a dual-drive Mach–Zehnder modulator and a balanced photodetector.The modulated optical signals from microwave photonic links can be directly demodulated and down-converted to intermediate frequency(IF)signals by the photonic mixer.The converted signal is obtained by conducting of-chip subtraction of the outputs from the balanced photodetector,and subsequent fltering of the high frequency items by an electrical low-pass flter.Benefting from balanced detection,the conversion gain of the IF signal is improved by 6 dB,and radio frequency leakage and common-mode noise are suppressed signifcantly.System-level simulations show that the frequency mixing system has a spurious-free dynamic range of 89 dB·Hz^(2/3),even with deteriorated linearity caused by the two cascaded modulators.The spur suppression ratio of the photonic mixer remains higher than 40 dB when the IF varies from 0.5 to 4 GHz.The electrical-electrical 3 dB bandwidth of frequency conversion is 11 GHz.The integrated frequency mixing approach is quite simple,requiring no extra optical flters or electrical 90°hybrid coupler,which makes the system more stable and with broader bandwidth so that it can meet the potential demand in practical applications.

Microstrip Patch Antenna with an Inverted T-Type Notch in the Partial Ground for Breast Cancer Detections

This study designs a microstrip patch antenna with an inverted T-type notch in the partial ground to detect tumorcells inside the human breast.The size of the current antenna is small enough(18mm×21mm×1.6mm)todistribute around the breast phantom.The operating frequency has been observed from6–14GHzwith a minimumreturn loss of−61.18 dB and themaximumgain of current proposed antenna is 5.8 dBiwhich is flexiblewith respectto the size of antenna.After the distribution of eight antennas around the breast phantom,the return loss curveswere observed in the presence and absence of tumor cells inside the breast phantom,and these observations showa sharp difference between the presence and absence of tumor cells.The simulated results show that this proposedantenna is suitable for early detection of cancerous cells inside the breast.

Development and Initial Assessment of a New Land Index for Microwave Humidity Sounder Cloud Detection

This paper describes a new quality control （QC） scheme for microwave humidity sounder （MHS） data assimilation. It consists of a cloud detection step and an O-B （i.e., differences of brightness temperatures between observations and model simulations） check. Over ocean, cloud detection can be carried out based on two MHS window channels and two Advanced Microwave Sounding Unit-A （AMSU-A） window channels, which can be used for obtaining cloud ice water path （IWP） and liquid water path （LWP）, respectively. Over land, cloud detection of microwave data becomes much more challenging due to a much larger emission contribution from land surface than that from cloud. The current MHS cloud detection over land employs an 0-]3 based method, which could fail to identify cloudy radiances when there is mismatch between actual clouds and model clouds. In this study, a new MHS observation based index is developed for identifying MHS cloudy radiances over land. The new land index for cloud detection exploits the large variability of brightness temperature observations among MHS channels over different clouds, It is shown that those MHS cloudy radiances that were otherwise missed by the current O-B based QC method can be successfully identified by the new land index. An O-B check can then be employed to the remaining data after cloud detection to remove additional outliers with model simulations deviated greatly from observations. It is shown that MHS channel correlations are significantly reduced by the newly proposed QC scheme.

Microwave Detection, Disruption, and Inactivation of Microorganisms

This paper reviews three complex interactions between microwave energy and microorganisms (bacteria, fungi, and viruses). The first interaction comprises the detection of viruses within human blood using a 50-Ohm transmission-line vector net-analyzer (typically 0 to 10 dBm @ 2 to 8.5 GHz) where the blood is placed within a test chamber that acts as a non-50-Ohm discontinuity. The second interaction employs 1 to 6.5 W @ 8 to 26 GHz for microwave feed-horn illumination to inactivate microorganisms at an applied power density of 10 to 100 mW-2. The third interaction is within multi-mode microwave ovens, where microorganism cell membrane disruption occurs at a few 100 s of W @ 2.45 GHz and microorganism inactivation between 300 to 1800 W @ 2.45 GHz. Within the first microwave interaction, blood relaxation processes are examined. Whereas in the latter two microwave interactions, the following disruption, and inactivation mechanisms are examined: chemical cellular lysis and, microwave resonant absorption causing cell wall rupture, and thermodynamic analysis in terms of process energy budget and suspension energy density. In addition, oven-specific parameters are discussed.

Assimilation of FY-3D MWTS-Ⅱ Radiance with 3D Precipitation Detection and the Impacts on Typhoon Forecasts

Precipitation detection is an essential step in radiance assimilation because the uncertainties in precipitation would affect the radiative transfer calculation and observation errors.The traditional precipitation detection method for microwave only detects clouds and precipitation horizontally,without considering the three-dimensional distribution of clouds.Extending precipitation detection from 2D to 3D is expected to bring more useful information to the data assimilation without using the all-sky approach.In this study,the 3D precipitation detection method is adopted to assimilate Microwave Temperature Sounder-2(MWTS-Ⅱ)onboard the Fengyun-3D,which can dynamically detect the channels above precipitating clouds by considering the near-real-time cloud parameters.Cycling data assimilation and forecasting experiments for Typhoons Lekima(2019)and Mitag(2019)are carried out.Compared with the control experiment,the quantity of assimilated data with the 3D precipitation detection increases by approximately 23%.The quality of the additional MWTS-Ⅱradiance data is close to the clear-sky data.The case studies show that the average root-mean-square errors(RMSE)of prognostic variables are reduced by 1.7%in the upper troposphere,leading to an average reduction of4.53%in typhoon track forecasts.The detailed diagnoses of Typhoon Lekima(2019)further show that the additional MWTS-Ⅱradiances brought by the 3D precipitation detection facilitate portraying a more reasonable circulation situation,thus providing more precise structures.This paper preliminarily proves that 3D precipitation detection has potential added value for increasing satellite data utilization and improving typhoon forecasts.

道路地下空洞探地雷达波场和时频特性

根据城市道路地下介质的分布特征和电性参数设计模型,采用时域有限差分法和广义S变换,对道路地下存在的充气空洞、充水空洞、回填不密实、埋藏金属物状态进行探地雷达正演模拟和时频特征提取。结果表明,地下空洞顶界面的反射波同相轴均呈弧形反射形态,但充气空洞的反射波能量强于充水空洞;地下空洞发育区域的中心频率集中在某个低频区间,其余频率成分分布较均匀;埋藏金属物区域出现两簇高幅值能量团,频率分布较分散;回填不密实区域频率未能显示出较明显的规律。最后,通过工程实测验证了数值模拟的可靠性。

微波消解-电感耦合等离子体质谱法测定有机肥中镉、砷、汞、铅、铬含量

采用电感耦合等离子体质谱法(ICP-MS)测定,比较湿法消解30 min,湿法消解至近干和微波消解等不同前处理方法对有机肥料中镉、砷、汞、铅、铬元素的提取效果,建立了一种基于ICP-MS测定有机肥料多种重金属元素含量的方法。结果表明:湿法消解至近干和微波消解法对有机肥多元素成分分析标准物质(RMH-F001)中5项重金属含量的测试结果均满足标准要求,方法定量值、标准值偏差分别低于6.3%、5.7%;硝酸/过氧化氢体系-微波消解处理下,样品结果稳定性最佳,相对标准偏差为0.8%~6.8%,相对偏差为1.1%~9.0%,相对相差为2.2%~18.0%,加标回收率为99.4%~102.9%。硝酸/过氧化氢体系-微波消解-ICP-MS法可作为有机肥中5项重金属统一化测定的常规方法。

虚实结合的传输线工作状态仿真与应用实验设计

针对传统微波实验少、教学难和设备维护成本较大、实验与工程脱节等问题,以同轴电缆故障检测为应用背景,将传输线理论与工程应用结合,设计虚实结合的传输线工作状态仿真与应用实验。采取工程问题引入、虚实结合、软硬搭配的方式,从传输线工作状态分析入手,利用终端短路和开路传输线模拟存在短路或断路故障的同轴电缆,通过仿真完成故障建模分析,掌握不同工作状态下电压、电流、阻抗和反射系数特性,自主设计方案完成故障检测。实践结果表明,传输线工作状态仿真与应用实验有利于学生深化对理论的理解、明晰理论的应用和提升解决工程问题能力,较好地满足实验教学要求。

基于弱磁探测的三相电缆路径快速定位方法

城市地下电缆的快速定位对于城市的安全稳定发展具有重要的意义,然而目前城市内地下电缆探测精度较差,可探测区域较小。针对上述难点问题,该文提出一种基于弱磁探测的三相电缆路径快速定位方法,并推导三相电缆磁场辐射的基本规律,通过测量空间中任意五点的磁场幅值信息,结合粒子群数值迭代计算方法,利用五点定位原理,推算得到地下三相电缆的路径。最后,通过仿真和实验验证该方法的可行性,并进行定位误差分析。该方法对于提高地下电缆探测精度和深埋电缆的探测能力有一定的参考价值。