Microwave Exposure Impairs Synaptic Plasticity in the Rat Hippocampus and PC12 Cells through Over-activation of the NMDA Receptor Signaling Pathway

Objective The aim of this study is to investigate whether microwave exposure would affect the N-methyI-D-aspartate receptor （NMDAR） signaling pathway to establish whether this plays a role in synaptic plasticity impairment. Methods 48 male Wistar rats were exposed to 30 mW/cm^2 microwave for 10 min every other day for three times. Hippocampal structure was observed through H＆E staining and transmission electron microscope. PC12 cells were exposed to 30 mW/cm^2 microwave for 5 min and the synapse morphology was visualized with scanning electron microscope and atomic force microscope. The release of amino acid neurotransmitters and calcium influx were detected. The expressions of several key NMDAR signaling molecules were evaluated. Results Microwave exposure caused injury in rat hippocampal structure and PC12 cells, especially the structure and quantity of synapses. The ratio of glutamic acid and gamma-aminobutyric acid neurotransmitters was increased and the intracellular calcium level was elevated in PC12 cells. A significant change in NMDAR subunits （NR1, NR2A, and NR2B） and related signaling molecules （CaZ＋/calmodulin-dependent kinase II gamma and phosphorylated cAMP-response element binding protein） were examined. Conclusion 30 mW/cm^2 microwave exposure resulted in alterations of synaptic structure, amino acid neurotransmitter release and calcium influx. NMDAR signaling molecules were closely associated with impaired synaptic plasticity.

Tunable microwave signal generation based on an Opto-DMD processor and a photonic crystal fiber

Frequency-tunable microwave signal generation is proposed and experimentally demonstrated with a dual-wavelength single-longitudinal-mode （SLM） erbium-doped fiber ring laser based on a digital Opto-DMD processor and four-wave mixing （FWM） in a high-nonlinear photonic crystal fiber （PCF）. The high-nonlinear PCF is employed for the generation of the FWM to obtain stable and uniform dual-wavelength oscillation. Two different short passive sub-ring cavities in the main ring cavity serve as mode filters to make SLM lasing. The two lasing wavelengths are electronically selected by loading different gratings on the Opto-DMD processor controlled with a computer. The wavelength spacing can be smartly adjusted from 0.165 nm to 1.08 nm within a tuning accuracy of 0.055 nm. Two microwave signals at 17.23 GHz and 27.47 GHz are achieved. The stability of the microwave signal is discussed. The system has the ability to generate a 137.36-GHz photonic millimeter signal at room temperature.

Low-intensive Microwave Signals in Biology and Medicine

Millimeter range signals have been widely used in biology and medicine over the 20-30 years of the last century.At this time in Ukraine have been developed and implemented treatment technologies,the main ones are millimeter therapy(MMT),microwave resonance therapy(MRT),information-wave therapy(IWT).The features of this technologies are the use of signals in the frequency band 40-78 GHz with extremely low signal levels-10-9-10-11 W/cm2,the parameters are immanent to own communication signals of the human body.The author of the article attempts to conduct a combined analysis of hardware and software of these treatment technologies with mm-band signals.Thus the specialized equipment used for the treatment,technologies and the statistical results of its use for various diseases are considered.The problems of metrological support and measuring the weak signals of the mm range are proposed to solve by creating highly sensitive radiometric systems.The results of measurements of microwave signals of natural objects that can be used for physiotherapy and physical bodies that are in contact with or in human environment are submitted.Promising areas of the using the highly sensitive radiometric measurement equipment for research in biology and medicine are presented.

Control of microwave signals using bichromatic electromechanically induced transparency in multimode circuit electromechanical systems

We theoretically investigate the tunable delay and advancement of microwave signals based on bichromatic electromechanically induced transparency in a three-mode circuit electromechanical system, where two nanomechanical resonators with closely spaced frequencies are independently coupled to a common microwave cavity. In the presence of a strong microwave pump field, we obtain two transparency windows accompanied by steep phase dispersion in the transmitted microwave probe field. The width of the transparency window and the group delay of the probe field can be controlled effectively by the power of the pump field. It is shown that the maximum group delay of 0.12 ms and the advancement of0.27 ms can be obtained in the current experiments.

Human Brain Microwave Imaging Signal Processing: Frequency Domain (S-parameters) to Time Domain Conversion

The paper presents the microwave signal processing method using MATLAB based on the result of microwave imaging system simulation developed using Computer Simulation Technology (CST). The simulation system contains a transmitting/receiving antenna, human brain and a tumor inside the brain model. The source signal, microwave signal operates from 1 to 10 GHz. The generated scattering parameters (S-parameters) are in frequency domain form. This paper describes in detail regarding the signal conversion from frequency domain to time domain through proposed Inverse Fast Fourier Transform (IFFT) method as well as the noise filtering process. Peaks detection process was performed in order to identify the time delay of the reflection points at different Y-axis

Tunable photonic microwave generated by multi-wavelength Brillouin fiber laser

Aimed at the problem of narrow tunability and low frequency microwave signal generated by the optical method,a novel approach to stabilizing the tunable photonic microwave generated by the multi-wavelength Brillouin fiber laser is proposed and is experimentally demonstrated.A singlelongitudinal-mode Brillouin fiber laser is designed,and by using the laser,a multi-wavelength Brillouin fiber laser with more than eleven orders of Stokes wave is observed.The wavelength spacing of the adjacent Stokes wave is 0.085 nm.If the Brillouin pump power is increased,the number of Stokes wave output can be further increased.The tunable microwave signals of 10.8 and 21.6 GHz are obtained by heterodyning the Rayleigh wave and Stokes wave of the multiwavelength Brillouin fiber laser.In the experiment,by tuning the pump wavelength and temperature of the gain fiber,microwave signals at different frequencies are generated.The tunable frequency range can be further expanded by using a temperature controller with a wider adjustment range,and the generated microwave signal exhibits high stability on frequency.

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.

Multifunctional mixed analog/digital signal processor based on integrated photonics

Photonic signal processing offers a versatile and promising toolkit for contemporary scenarios ranging from digital optical communication to analog microwave operation.Compared to its electronic counterpart,it eliminates inherent bandwidth limitations and meanwhile exhibits the potential to provide unparalleled scalability and flexibility,particularly through integrated photonics.However,by far the on-chip solutions for optical signal processing are often tailored to specific tasks,which lacks versatility across diverse applications.Here,we propose a streamlined chip-level signal processing architecture that integrates different active and passive building blocks in silicon-on-insulator(SOI)platform with a compact and efficient manner.Comprehensive and in-depth analyses for the architecture are conducted at levels of device,system,and application.Accompanied by appropriate configuring schemes,the photonic circuitry supports loading and processing both analog and digital signals simultaneously.Three distinct tasks are facilitated with one single chip across several mainstream fields,spanning optical computing,microwave photonics,and optical communications.Notably,it has demonstrated competitive performance in functions like image processing,spectrum filtering,and electro-optical bandwidth equalization.Boasting high universality and a compact form factor,the proposed architecture is poised to be instrumental for next-generation functional fusion systems.

一种采用斜波比较的精细步进延时系统

为了实现高频信号在欠采样条件下的波形重构,步进延迟脉冲信号的产生成为顺序等效时间采样技术用于触发取样系统进行高频信号采样的关键。为此,对精细延时方法进行研究,采用斜波比较的方法设计了一种精细步进延时系统,该系统基于微波三极管的开关特性,结合恒流源、充放电电路、高速电压比较器以及可编程DAC产生可调步进延迟时间的触发序列。对该系统进行仿真分析以及实验测试。实验结果表明,电容放电的线性区域下降沿时间为10 ns,幅度为4~7 V,与DAC比较后输出延迟脉冲的步进范围为10 ns,单位步进延迟精度可达1 ps。该斜波比较精细步进延迟系统可应用于取样示波器、矢量网络分析仪等测试仪器中,实现通信、雷达等信号探测与分析,对于高频信号的获取与分析具有重要意义。

On Differentiation Among Pilot Signals of Multiple Mobile Targets in Retro-Reflective Beamforming for Wireless Power Transmission

An experimental study is conducted on several retro-reflective beamforming schemes for wireless power transmission to multiple wireless power receivers(referred to herein as“targets”).The experimental results demonstrate that,when multiple targets broadcast continuous-wave pilot signals at respective frequencies,a retro-reflective wireless power transmitter is capable of generating multiple wireless power beams aiming at the respective targets as long as the multiple pilot signals are explicitly separated from one another by the wireless power transmitter.However,various practical complications are identified when the pilot signals of multiple targets are not appropriately differentiated from each other by the wireless power transmitter.Specifically,when multiple pilot signals are considered to be carried by the same frequency,the wireless power transmission performance becomes heavily dependent on the interaction among the pilot signals,which is highly undesirable in practice.In conclusion,it is essential for a retro-reflective wireless power transmitter to explicitly discriminate multiple targets’pilot signals among each other.

基于反馈机制的光子微波信号级联滤波方法

光子微波通信过程中,受噪声影响造成带宽变窄,降低了通信效率。为了优化光子微波通信质量,提出基于反馈机制的光子微波信号级联滤波方法。利用形态学腐蚀和膨胀去除信号模糊程度后,将相似度较高的信号聚集为连续区域,完成微波信号去噪。选用卡尔曼滤波器对微波信号测量噪声初次滤波,使用均值滤波以及双门限输出方案二次滤波双路光电反馈下生成的微波信号。通过两种滤波器的级联处理,去除微波信号中不同的杂波,实现窄线宽光子微波信号级联滤波。实验结果表明,所提方法级联滤波波动幅度小,能够平稳输出滤波结果,且不同温度下的级联滤波衰减特性相对平稳。

微波含水率检测技术在复杂油水混合形态下的应用研究

在油水混合物中会出现不同的乳化形态,不同的乳化形态对应的电导率和介电常数也具有显著差异,从而导致通过检测电导率和介电常数值间接测量含水率的测量结果不准确。针对复杂油水混合状态下含水率难以测准的问题,提出一种基于微波技术的复杂油水两相流含水率检测技术,建立了基于微波技术的“油包水”和“水包油”状态分析方法。首先通过检测微波信号穿过不同介质后信号幅值的衰减和相位的偏移,推测油水混合物的含水率值。再利用不同输入功率的微波信号在不同介电常数下功率衰减比不同的原理,来区分油水混合物的乳化状态,优化含水率的测量。室内验证和矿场试验结果表明,该系统可有效区分乳化液的混合状态,通过含水率标定值对实测数据进行修正,最终测量的含水率误差可控制在1个百分点以内,实现了复杂油水混合形态下含水率的高精度测量。

基于新型高功率微波的雷达探测技术研究

本文研究提出一种新型高功率微波窄脉冲,能够具备雷达探测能力,适用于解决单脉冲探测雷达功率不足的问题。新型高功率微窄脉冲为ns级脉冲信号,具备中心载频信息并且具有超高重频、超高功率、超高带宽的特性。根据该脉冲特性,本文深入探索提出一种基于新型高功率微波的雷达探测方法,该方法采用基于脉冲路径编码压缩的物理脉冲压缩方式获得一种新型高功率微波窄脉冲,通过单脉冲探测的方式实现对目标探测侦察。经数值仿真模拟与实际测量对比分析表明,对于探测雷达系统而言,基于脉冲路径编码压缩方法能够在现有功率源基础上提高20 dB以上的信号增益。通过多目标探测实验验证,新型高功率微波雷达系统能够有效探测目标,其系统距离测量精度误差小于5‰。实验证明:新型高功率微波窄脉冲具有雷达探测能力,能有效提高系统探测功率,提升系统探测距离。

基于DP-MZM调制交/直流功率检测的瞬时频率测量

提出了一种基于双平行马赫-曾德尔调制器(DP-MZM)调制单支路交/直流功率检测的瞬时频率测量(IFM)方案。通过引入可调的射频时延将射频频率信息映射到光场相位,再经光电转换传递至交/直流功率比函数,即幅度比较函数(ACF),再利用ACF映射关系实现射频信号的瞬时频率测量。对方案进行了理论分析与计算,结果表明,ACF曲线仅与射频时延差有关,通过调节延迟线引入的时延差可实现测频范围的大范围可调。对系统进行了仿真验证,结果表明,测频范围为0~16.7 GHz的IFM系统方案的误差范围为±200 MHz。最后,对影响测频精度的调制系数、调制器偏置电压漂移、调制器消光比进行了讨论,得到了各自的容差范围。

Background-free pulsed microwave signal generation based on spectral shaping and frequency-to-time mapping

A novel scheme for the generation of background-free pulsed microwave signals is proposed and experimentally demonstrated based on spectral shaping,frequency-to-time mapping,and balanced photodetection.In the proposed scheme,the optical spectral shaper,which consists of a differential group delay(DGD)element,two polarization controllers,and a polarization beam splitter,has two outputs with complementary power transfer functions.By passing a short optical pulse through the spectral shaper and a dispersive element(DE),a pulsed microwave signal is obtained after balanced photodetection.Thanks to the balanced photodetection,the lowfrequency components(i.e.,the background signal)in the electrical spectrum is suppressed,leading to the generation of a background-free pulsed microwave signal.Meanwhile,the spectral power of the obtained microwave signal is enhanced compared to that obtained by single-end detection.Experimental results for the generation of a pulsed microwave signal centered at 12.46 GHz show that the background signal can be suppressed by more than 30 dB,and the spectral power is increased by 5.5 dB.In addition,the central frequency of the obtained background-free pulsed microwave signal can be tuned by changing the DGD introduced by the DGD element,and/or by changing the dispersion of the DE.

IP微波通信在广播电视信号传输中的应用

网际互连协议(Internet Protocol,IP)微波通信作为一种新兴技术,具有广阔的应用前景,尤其在广播电视信号传输领域。从IP微波通信技术的概念入手,探讨了IP微波通信的主要技术类型,分析了IP微波通信在广播电视信号传输中的具体应用。

集成互注入半导体激光器的微波光子学应用

光源是微波光子(microwave photonic,MWP)系统的“发动机”,从根本上决定了系统性能的上限。光注入半导体激光器集聚诸多优势,但离散器件引发的系统集成度低、结构复杂、体积大、稳定性差等弊端明显,大大限制了MWP系统的工程化应用。集成化是解决目前MWP技术实用化等瓶颈问题的关键,轻量级、高性能、多功能的激光器光源是集成MWP系统的关键。基于此,本文综述了近年来集成互注入半导体激光器在高效电光转换、微波信号产生、MWP变频、弱信号探测以及光学频率梳源等MWP应用方面的创新研究,期望为集成MWP系统提供可行的高性能集成光源,推动集成MWP技术的工程化应用尽快实现。

High-power linear-polarization burst-mode all-fibre laser and generation of frequency-adjustable microwave signal

Narrowband microwave generation with tuneable frequency is demonstrated by illuminating a photoconductive semiconductor switch(PCSS)with a burst-mode fibre laser.The whole system is composed of a high-power linearly polarized burst-mode pulsed fibre laser and a linear-state PCSS.To obtain a high-performance microwave signal,a desired envelope of burst is necessary and a pulse pre-compensation technique is adopted to avoid envelope distortion induced by the gain-saturation effect.Resulting from the technique,homogenous peak power distribution in each burst is ensured.The maximum energy of the laser burst pulse reaches 200μJ with a burst duration of 100 ns at the average power of 10 W,corresponding to a peak power of 4 kW.When the PCSS is illuminated by the burst-mode fibre laser,narrowband microwave generation with tuneable frequency(0.80-1.12 GHz)is obtained with a power up to 300 W.To the best of the authors’knowledge,it is the first demonstration of frequency-tuneable narrowband microwave generation based on a fibre laser.The high-power burst-mode fibre laser reported here has great potential for generating high-power arbitrary microwave signals for a great deal of applicable demands such as smart adaptive radar and intelligent high-power microwave systems.

省级广电微波机房的安播监控系统设计与实现

本文设计一套广播电视信号监控系统,实现对全省微波台站信号传输的有效监控。文章通过分析广播电视信号监控需求,介绍搭建信号监控系统的架构方案和具体软硬件配置要点,从而进一步完善安播信号监管能力,保障广播电视信号安全播出。

频域宽带阵列波束形成技术优化设计

为提高宽带相控阵系统的波束合成性能,文章针对宽带相控阵系统中的延时补偿问题,采用频域宽带阵列波束形成的方法,分析了宽带相控阵中应用交叠FFT进行时延补偿的原理和误差造成的原因;基于一个接收信号带宽为600 MHz的64阵元的宽带相控阵系统,研究了子阵规模、FFT点数、交叠率、位宽、采样率等交叠FFT参数对延时精度、信号保真度和波束性能的影响,在满足工程应用要求的同时对频域宽带阵列波束合成技术进行了优化;经研究确定子阵规模不超过9个天线阵元、FFT点数不小于512、交叠率不小于1/16、位宽不小于采用12 bit时可以达到指标的要求,为交叠FFT方法应用在实际工程中提供了依据与参考,并使其工程实现复杂度降低。