Synthesis and Design of 5G Duplexer Based on Optimization Method

A new optimization method is proposed to realize the synthesis of duplexers.The traditional optimization method takes all the variables of the duplexer into account,resulting in too many variables to be optimized when the order of the duplexer is too high,so it is not easy to fall into the local solution.In order to solve this problem,a new optimization strategy is proposed in this paper,that is,two-channel filters are optimized separately,which can reduce the number of optimization variables and greatly reduce the probability of results falling into local solutions.The optimization method combines the self-adaptive differential evolution algorithm(SADE)with the Levenberg-Marquardt(LM)algorithm to get a global solution more easily and accelerate the optimization speed.To verify its practical value,we design a 5 G duplexer based on the proposed method.The duplexer has a large external coupling,and how to achieve a feed structure with a large coupling bandwidth at the source is also discussed.The experimental results show that the proposed optimization method can realize the synthesis of higher-order duplexers compared with the traditional methods.

Research of electromagnetic field in different length left-handed material slab

Finite-difference time-domain(FDTD) method is used to simulate the propagation of electromagnetic wave in left-handed material slab(LHMs) with cold plasma model The effects of optical propagation in the left-handed material compared to convex lens are discussed.The wider the LHMs is,the stronger electric field of focusing image in left-handed material slab is confirmed by the simulation with various slab length.However,the outer image point location would slightly moves to the LHMs side when the length of LHMs is reduced.

Compact Dual-Band Zeroth-Order Resonance Antenna

A novel microstrip zeroth-order resonator (ZOR) antenna and its equivalent circuit model are exploited with two zeroth-order resonances.It is constructed based on a resonant-type composite right/left handed transmission line (CRLH TL) using a Wunderlich-shaped extended complementary single split ring resonator pair (W-ECSSRRP) and a series capacitive gap.The gap either can be utilized for double negative (DNG) ZOR antenna or be removed to engineer a simplified elision-negative ZOR (ENG) antenna.For verification,a DNG ZOR antenna sample is fabricated and measured.Numerical and experimental results agree well with each other,indicating that the omnidirectional radiations occur at two frequency bands which are accounted for by two shunt branches in the circuit model.The size of the antenna is 49% more compact than its previous counterpart.The superiority of WECSSRRP over CSSRRP lies in the lower fundamental resonance of the antenna by 38.2% and the introduction of a higher zeroth-order resonance.

Electrodynamic Analysis of Dissipative Electromagnetic Materials Based on Fractional Derivative

The generalized Lagrangian is defined in a dissipative electromagnetic medium on the basis of the combination of dynamical analysis and fractional derivative. Lorentz medium models are obtained by formulating relevant Euler-Lagrange equations. The invariance is obtained subsequently by investigating the invariance of time variation in the system, and then the relation between the related Hamiltonian and electromagnetic energy density is investigated. Canonical equations are obtained eventually. The electrodynamic interpretation on dissipative electromagnetic systems is revealed.

EFFECT OF FEED ARRAY CONFIGURATION ON THE FIELD-OF-VIEW OF RADIO TELESCOPE ANTENNA

Phased Array Feed (PAF) is a small two-dimensional phased array antenna, playing a role as the multi-beam feed for the reflector antenna. The prominent capability of large continuous Field-of-View (FoV) coverage and fast survey speed makes PAF the promising feed for radio telescopes. In this paper, the effect of feed array of PAF on the gain fluctuations over FoV is analyzed on a sim- plified model of the Five-hundred-meter Spherical Aperture radio Telescope (FAST), including illu- mination pattern edge taper, element spacing, element arrangement and element amount. And the differences between rectangular and hexagonal array arrangements are compared. The relationship between the FoV and array configuration are concluded at last.

舰载多天线系统电磁兼容性分析

针对舰载多天线系统电磁兼容性(EMC)分析计算量大、耗时过长问题,提出了自动分层的多层快速多极子方法(MLFMA)。采用BiCGStab(l)结合近场预条件方法进行求解,进一步提高了MLFMA的综合效率。为了分析天线间的近场耦合特性,运用微波网络理论结合互易定理给出了任意天线间的隔离度表达式。计算并分析了尺度与真实尺寸相当的某舰船模型上多根超短波天线的辐射方向图和天线间的隔离度。数值结果表明算法准确有效,并且对于电大运载平台中天线布局优化具有一定的指导意义。

Convolution neural network and 77 GHz millimeter wave radar based intelligent liquid classification system

An intelligent liquid classification system based on 77 GHz millimeter wave radar and convolution neural network are proposed in this paper.The data are collected by the AWR1843 radar platform and processed by the neural network on the host PC in real-time.The doppler heatmap generated by radar signal processing is tried for the first time as the input of the system.The information carried by the heatmap in 2 dimensions is analyzed and the reason why the doppler heatmap could be used for classification is explained.The feasible experiment proved that the proposed method can successfully classify 8 kinds of common liquid with high accuracy.The result of the experiment is explained and the limitations of the experiment are discussed.It can be drawn that the combination of FMCW millimeter wave radar and convolution neural network is a method with great potential for liquid classification.The advantages of real time,non-invasive and unilateral measurement can also be used for the detection of dangerous liquids.

Wideband and low sidelobe graphene antenna array for 5G applications

The upcoming fifth-generation(5G)mobile communication with low-latency,high-speed and high-data-capacity[1]can realize innovative services such as remote intelligent medical care,smart cities,Internet of Vehicles,and ultra-high-definition video[2,3].Compared with current mobile communications,5G services require a 5G network with 1000 times the capacity and 10–100 times the data transmission rate[4].5G communication can also realize large-scale connections between people and machines[5].It will be the era of Internet of Everything.The realization of the interconnection of all things is essentially the communication between the transmitting antenna and the receiving antenna.

Optimal design of a large dual-polarization microstrip reflectarray with China-coverage patterns for satellite communications

A large dual-polarization microstrip reflectarray with China-coverage patterns in two operating bands is designed.To sufficiently compensate for the spatial phase delay differences in two operating bands separately,a three-layer rectangular patch element is addressed,which is suitable for the large dual-polarization reflectarray.Due to the complexly shaped areas and high gain requirements,there are more than 25000 elements in the reflectarray,making it difficult to design,due to more than 150000 optimization variables.First,the discrete fast Fourier transform(DFFT)and the inverse DFFT are used to establish a one-to-one relationship between the aperture distribution and the far field,which lays a foundation for optimizing the shaped-beam reflectarray.The intersection approach,based on the alternating projection,is used to obtain the desired reflection phases of all the elements at some sample frequencies,and a new method for producing a suitable initial solution is proposed to avoid undesired local minima.To validate the design method,a dual-polarization shaped-beam reflectarray with 7569 elements is fabricated and measured.The measurement results are in reasonable agreement with the simulation ones.Then,for the large broadband reflectarray with the minimum differential spatial phase delays in the operating band,an approach for determining the optimal position of the feed is discussed.To simultaneously find optimal dimensions of each element in two orthogonal directions,we establish a new optimization model,which is solved by the regular polyhedron method.Finally,a dual-band dual-polarization microstrip reflectarray with 25305 elements is designed to cover the continent of China.Simulation results show that patterns of the reflectarray meet the China-coverage requirements in two operating bands,and that the proposed optimization method for designing large reflectarrays with complexly shaped patterns is reliable and efficient.

Optic eikonal, Fermat’s principle and the least action principle

A generalized refractive index in the form of optic eikonal is defined through com- paring frame definitions of left-handed and right-handed sets and indicates the sign of the refractive index covered by the quadratic form of the eikonal equation. Fer- mat’s principle is generalized, and the general refractive law is derived directly. Under this definition, the comparison between Fermat’s principle and the least ac- tion principle is made through employing path integral and analogizing L. de Broglie’s theory.

A novel wideband ring antenna for polarization/pattern diversity

We present a novel wideband ring antenna for polarization/pattern diversity.The proposed antenna consists of eight printed dipole elements in the form ofacircular array.The arms of adjacent elements overlap for capacitive loading Unlike traditional circular arrays,a method of exciting elements in the form of every two intervals is first introduced.

Wideband Circularly Polarized Sequentially Rotated Microstrip Antenna Array with Sequential-Phase Feeding Network

A wideband 2×2 sequential-phase fed circularly polarized(CP)microstrip antenna array(MAA)with sequentially rotated elements is proposed.Firstly,the antenna element loaded with shorting pins is studied as compared to the traditional counterpart.Then,a feeding network is designed to be connected together in a sequential rotation manner,resulting in forming a four-port network to allow symmetrical positioning of CP microstrip patch elements.After that,straight strips are added to the feeding network in order to increase the distance and reduce coupling between array elements.They also play a role in improving the impedance matching of the array.Finally,the proposed antenna array is designed and simulated.The results are presented that its impedance bandwidth is about 36.3%at 24.1~34.8 GHz for|S_(11)|<10 dB and axial-ratio(AR)bandwidth is about 20.4%at 24.2~29.7 GHz for AR【3 dB.Besides,a peak gain of 11.1 dBic is simulated over the operating frequency range,which is significantly improved compared to the classic and existing works.

Analysis of airborne antenna using a FEM-UTD hybrid method

In this paper,the near-field vector components were used to combine the FEM method and the uniform-geometrical theory of diffraction(UTD)method for analyzing phased array antenna mounted on an airborne platform.First,HFSS,a set of software based on finite element method(FEM),was utilized to find the near-field vector components of the phased array antennas,and then these vector components were used as the source of the UTD method to get the disturbed radiation pattern.Numerical results show that the hybrid of the two methods not only extends the use of the UTD program,but also effectively solves this type of challenging problems.

Ultra-high conductive graphene assembled film for millimeter wave electromagnetic protection

轻质、高效、耐腐蚀、易于大规模制备的电磁防护材料正受到越来越多的关注.本文提出了一种二次高温退火工艺,大规模制备具有超高电导率的石墨烯组装膜,并应用于毫米波频段电磁防护.二次退火工艺提高了石墨烯组装膜的结晶度和层间规则性,使片层间接触电阻降低,电导率得到显著提升.石墨烯组装膜在超宽频带内都具备优异的电磁屏蔽性能,远高于目前所报道的相同厚度的各类碳基材料.另外,本文还研制了一种超低面密度且具有良好角度稳定性的毫米波石墨烯频率选择表面.石墨烯频段选择表面继承了石墨烯组装膜的特性,具有良好的柔韧性、高导热性和优异的机械稳定性.本研究采用标准方法证明了石墨烯组装膜用于毫米波电磁屏蔽和频率选择表面等电磁防护的新概念,从而开辟了一个新的研究方向.