Transmission Performance of the Optical Millimeter-wave Up-conversion Link Using a Phase Modulator

Numerically analyzed is the transmission performance of the optical millimeter （mm）-wave generated by frequency up-conversion via a phase modulator along the dispersive fiber. 60 GHz ram-wave subcarrier（SC） signals can be obtained after fiber transmission, simultaneously, the phase-modulated signals can be converted to the intensity-modulated ones. The numerical results show that the optical ram-wave at fading loops has better performance, and the eye diagram still keeps open when optical mm-wave signal is transmitted over 98 km.

Wide-Angle Scanning Antennas for Millimeter-Wave 5G Applications

The fifth generation(5G)network communication systems operate in the millimeter waves and are expected to provide a much higher data rate in the multi-gigabit range,which is impossible to achieve using current wireless services,including the sub-6 GHz band.In this work,we briefly review several existing designs of millimeter-wave phased arrays for 5G applications,beginning with the low-profile antenna array designs that either are fixed beam or scan the beam only in one plane.We then move on to array systems that offer two-dimensional(2D)scan capability,which is highly desirable for a majority of 5G applications.Next,in the main body of the paper,we discuss two different strategies for designing scanning arrays,both of which circumvent the use of conventional phase shifters to achieve beam scanning.We note that it is highly desirable to search for alternatives to conventional phase shifters in the millimeter-wave range because legacy phase shifters are both lossy and costly;furthermore,alternatives such as active phase shifters,which include radio frequency amplifiers,are both expensive and power-hungry.Given this backdrop,we propose two different antenna systems with potential for the desired 2D scan performance in the millimeter-wave range.The first of these is a Luneburg lens,which is excited either by a 2D waveguide array or by a microstrip patch antenna array to realize 2D scan capability.Next,for second design,we turn to phased-array designs in which the conventional phase shifter is replaced by switchable PIN diodes or varactor diodes,inserted between radiating slots in a waveguide to provide the desired phase shifts for scanning.Finally,we discuss several approaches to enhance the gain of the array by modifying the conventional array configurations.We describe novel techniques for realizing both one-dimensional(1D)and 2D scans by using a reconfigurable metasurface type of panels.

A Novel Millimeter-Wave Channel Measurement Platform for 6G Intelligent Railway Scenarios

This paper presented a novel millimeterwave channel measurement platform for the 6G intelligent railway.This platform used phased array antenna with 64 elements and can support instant bandwidth up to 1 GHz.Combined with improved multi-tone sounding signals,the platform can enhance dynamic measurement capability in high-speed railway scenarios.We performed calibration works about frequency flatness,frequency offset and proved platform reliability with channel emulator based closed-loop verification.We also carried out field trials in high-speed railway carriage scenarios.Based on measurement results,we extracted channel characteristic parameters of path loss,power delay profile and delay spread to further verify the field measurement performance of the platform.

Low phase noise and quasi-tunable millimeter-wave generator using a passively In As/InP mode-locked quantum dot laser

A low phase noise millimeter-wave(MMW) signal generator is proposed and experimentally demonstrated with a C-band passively Fabry-Pérot(F-P) quantum dot mode-locked laser. A novel method is proposed to generate low phase noise MMW signal, which is simply based on a commercial off-the-shelf dual-driven Li Nb O3 Mach-Zehnder modulator and a passively F-P quantum dot mode-locked laser. MMW signal with the frequency of 30 GHz, 45 GHz and 90 GHz respectively is obtained experimentally. Single-sideband phase noise of the 30 GHz and 45 GHz MMW signal is-112 d Bc/Hz and-106 d Bc/Hz at an offset of 1 k Hz, respectively. The linewidth of the 30 GHz and 45 GHz MMW signal is about from 225 Hz and 239 Hz. This is considered a very simple MMW generator with a quasi-tunable broadband and ultra-low phase noise.

Beam squint effect on high-throughput millimeter-wave communication with an ultra-massive phased array

An ultra-massive phased array can be deployed in high-throughput millimeter-wave(mmWave)communication systems to increase the transmission distance.However,when the signal bandwidth is large,the antenna array response changes with the frequency,causing beam squint.In this paper,we investigate the beam squint effect on a high-throughput mmWave communication system with the single-carrier frequency-domain equalization transmission scheme.Specifically,we first view analog beamforming and the physical channel as a spatial equivalent channel.The characteristics of the spatial equivalent channel are analyzed which behaves like frequency-selective fading.To eliminate the deep fading points in the spatial equivalent channel,an advanced analog beamforming method is proposed based on the Zadoff-Chu(ZC)sequence.Then,the low-complexity linear zero-forcing and minimum mean squared error equalizers are considered at the receiver.Simulation results indicate that the proposed ZC-based analog beamforming method can effectively mitigate the performance loss by the beam squint.

相位连续可调毫米波MEMS移相器的研制

MEMS毫米波相移器是MEMS毫米波相控阵天线的关键部件之一,它的性能直接决定了毫米波相控阵天线的性能。该文介绍毫米波MEMS相移器的设计,研究低损耗衬底,Au,AlxSi1-x可动膜对下拉电压和传输损耗的影响,测试表明:21桥相位连续可调的分布式压控开关阵列一毫米波相移器在35GHz时,启动电压5V,20V时相移量达到372°/3.5 mm,并能在不同的控制电压下根据要求改变相移量。

差异模式视差检测模型与特征视差

视差检测细胞都会在某一刺激视差值处有最大响应 ,这表明细胞响应只对刺激的视差敏感 ,而与具体的刺激特征无关 .利用接受差异模式简单细胞输入的复杂细胞能量模型的响应公式 ,对特征视差的机制进行了研究 ,认为适合于视差检测的细胞类型 ,其本质是细胞具有空间频率选择特性 ;复杂细胞接受位置差编码方式的简单细胞输入时 ,具有精确的特征视差 ,而接受相位差编码方式的简单细胞输入时 。

相差变化率的无模糊测量

首先,描述了基于多通道相差测量的相差变化率表示式,通过将对应于基线长度的时差项从相差变化率中剥离出来,提取得到了一个在单位长度上表征波长整周数和相差的差分特性的函数。随后所做的模拟计算发现,单位长度上的程差差分函数的变化是极有规律的,直接通过对实测获得的相差差分值域的判别,就能确定相应的校正数,由此得到的与波长整周数差分项无关的、且与原程差差分函数等值的函数表示式。本文的研究结果无疑为与相位测量相关的工程实用化设计提供了一种很有力的技术支撑。

极化效应作用下长方体各向同性电光晶体中光束相移的解析计算

电光晶体中光束相移的计算对光学电场传感器的研究至关重要,但空间电场作用下晶体极化效应对光束相移的影响尚未得到深入理解。该文提出极化效应作用下长方体各向同性电光晶体中光束相移的计算方法,定义电场变换张量以描述极化效应作用下晶体内部电场与空间电场之间的关联关系,推导出引入电场变换张量的光束相移公式。该方法同时考虑空间电场作用下电光晶体和环境介质的极化效应,可用于计算具有任意三维尺寸和介电特性的长方体各向同性电光晶体中的光束相移。结果表明:电光晶体与环境介质的介电常数之比是关键因素,该比例的增加会引起光束相移的非线性衰减;晶体三维尺寸的变化均会对光束相移产生显著影响;光束在晶体中的传播路径也是影响光束相移的重要因素。最后,以BGO晶体为例开展实验,验证相移公式的有效性。该文研究可为电光晶体中光束相移的计算评估以及光学电场传感器的优化设计提供理论依据。

调制域分析技术中一种新颖的提高测量精度方法

本文提出了一种新颖的调制域分析中提高测量精度的方法,即时标移相法,并且进行了改进。时标移相法通过对时标信号进行等相位移相,然后对移相后的各时标分别计数,使等效时标频率为实际时标频率移相次数的倍数,因此测时分辨率也提高到移相次数的倍数,从而提高测量精度。该方法与传统的模拟内插、数字游标及延迟内插法比较,电路简单,系统频率低,对电路设计和元器件的要求低,在工程上容易实现,并且调试测试方便,但又能达到同样的测量精度。本方法在某型调制域分析项目中进行了验证,提高测量精度的结果符合预期,在工程实现上切实可行。