最新刊期
卷 42 ， 期 1 ， 2014
- 摘要：A frequency modulated continue wave (FMCW) rotating synthetic aperture radar (ROSAR) imaging mode and corresponding imaging algorithm are presented.Firstly,the separated transmit antenna and receive antenna system are equalized to the case of system configuration with antenna both for transmitting and receiving signals according to the equivalent phase center principle.Based on this,by approximating the slant equation with the higher order model,one can obtain accurate two-dimensional frequency spectrum via the series reversion method.The Doppler frequency shift effect,induced by the platform's continuous motion while radar transmits and receives signals,is analyzed and the approximate compensation method is shown.Finally,efficient Chirp-Z transform (CZT) is applied to correct the range-variant range cell migration (RCM) and well-focused SAR image is obtained.Simulation results verify the correctness of the analysis and the validity of the proposed algorithm.关键词：helicopter-borne rotating synthetic aperture radar;frequency modulated continuous wave;Chirp-Z transform;two-dimension spectrum2|2|1更新时间：2025-07-16
- 摘要：In this paper,a new similarity measure for SAR imagery based on local gradient ratio pattern is proposed.Firstly,we extract the gradient ratio pattern for each pixel.Secondly,the local gradient ratio pattern histogram(LGRPH)is computed.Finally,the similarity is obtained by utilizing K-L discrepancy to measure the distance of LGRPH.Experimental results based on simulated and real SAR images demonstrate that the proposed similarity measure is robust to the speckle noise and local gradient variation in SAR images.关键词：SAR image;local gradient ratio;similarity measure;target recognition3|4|1更新时间：2025-07-16
- 摘要：Computation burden and the processing complexity of interpolation operation are the problems Keystone formatting faces.Especially in STAP,where Keystone formatting should be applied to each of the element,which makes it unfeasible for real time processing.Based on these,a new practical method with low computation burden is given,which removes the clutter firstly,and a space domain beam forming is done;after that,Keystone formatting is applied to the beam domain data for range walk compensation.By the proposed method,only one Keystone formatting is needed compared with the KF-STAP method,therefore,the computation burden can be reduced dramatically.Besides,a compressed sensing (CS) based targets' parameter estimation method is proposed for the targets' velocity estimation of STAP.Effectiveness of the proposed methods is verified via simulation examples.关键词：airborne radar;space-time adaptive processing (STAP);moving target detection;keystone formatting;compressed sensing (CS)2|3|3更新时间：2025-07-16
- 摘要：Splitting a whole large file into some small blocks and distributedly deploying these block replications on severs can improve their application efficiency and meet users' demands.How to split a file,how many replications of a block should be created,and how to deploy these replications become the most critical issures in this field.In this paper,considering client's demands for each block,we introduce block-popularity and present a block deployment strategy according to it,called minimum cost of storing blocks (MCSB),which can satisfy users' requirement and minimum storage cost.In our strategy,through introducing cost adjustment factors of blocks,not only that lower hot blocks are assured to deploy earlier,but also the practical total storage cost are not exceed than the original case.To maintain the performance of service system,we study resource management methods in-depth among severs with different workloads and propose an adaptive MCSB strategy (AMCSB).We implement the MCSB (and AMCSB) in Hadoop and compare their performance with other related strategies.The experiment results show that MCSB fulfills minimum service cost and shortens average response time,and AMCSB realizes load balance among target servers.关键词：cloud storage;data block;MCSB;AMCSB;big data2|2|9更新时间：2025-07-16
- 摘要：A novel hierarchical access control scheme for perceptual layer of the IoT is presented based on resources hierarchies,which could conform to the secure and efficient access requirement of multi-user.In the scheme,every hierarchical node is composed of perceptual nodes which provide resources with the same levels of security.More hierarchical nodes can be modeled as a set of partially ordered classes.With this mode,a deterministic key derivation algorithm is designed,which makes every user and perceptual node possesses a single key material to get some keys,and obtains the resources at the presented class and all descendant classes in the hierarchy.Furthermore,a mechanism of Merkle tree is introduced to guarantee secure and efficient multi-user key material derivation by independent of each hash link.Compared with previous proposals,the scheme is more suitable for multi-user to access resources of perceptual layer in IoT.关键词：Internet of Things;perceptual layer;access control;resources hierarchies;provable security2|4|3更新时间：2025-07-16
- 摘要：The performance of a multi-antenna two-hop amplify-and-forward (AF) relay system with feedback delay over mixed fading channels is studied,where the source-relay and relay-destination links follow Rayleigh and Rician fading,respectively.Based on the beamforming (BF) model with feedback delay,we first obtain the equivalent output signal-to-noise ratio (SNR) for the AF relaying.With the help of infinite-series representation,we then derive the analytical expressions for the outage probability (OP) and probability density function (PDF) of the output SNR.Furthermore,the theoretical formulas of the Ergodic capacity and average symbol error rates (ASERs) of the system are also developed.Finally,the analytical results are verified through comparison with Monte Carlo simulations,where the effects of antenna number,feedback delay and channel parameters on the system performance are also investigated.关键词：amplify-and-forward relaying;mixed fading channels;beamforming;performance analysis3|4|0更新时间：2025-07-16
- 摘要：Momentum term technology is an effective solution to improve the performance of the adaptive blind source separation (BSS) algorithm,but the convergence property of the momentum term based BSS algorithm is very sensitive to the fixed momentum factor,and its performance in steady state is also restricted by the step size. Firstly,the principle of the momentum term based BSS algorithm as well as its two disadvantages were presented and analyzed in this paper. Then,in order to eliminate the first disadvantage of the momentum term based algorithm using the fixed momentum factor,we structured a variable momentum factor algorithm with the adaptive adjustment property based on the gradient descent method. On this basis,by virtue of the convex combination theory,an adaptive combination of tow variable momentum factor algorithms with different step size was proposed to alleviate the performance restriction caused by the step size. The simulation results in different conditions demonstrate that the proposed modified strategies got the optimization balance between the fast convergence speed and small steady-state error,and effectively avoid the two drawbacks of the momentum term based BSS algorithm.关键词：blind source separation;momentum term;momentum factor;convex combination;step size2|2|7更新时间：2025-07-16
- 摘要：With the limitation of the error function used in adaptive notch filter (ANF),the convergence speed of the adaptive frequency estimation method is slow and the setting of initial iteration frequency value is also restrained.Especially for the signal whose frequency is close to 0 or π,the frequency estimation accuracy is not satisfied and the stability of ANF is poor,so a new frequency estimation method of ANF based on new error function is proposed.Firstly,the reasons for low accuracy,slow convergence speed and poor stability of ANF frequency estimation methods are analyzed,and a new error function is proposed to improve the convergence speed;secondly,according to the reasons of the bias generated by ANF,a bias removing technique is adopted to improve the accuracy of the frequency estimation and the unbiased frequency estimation results are obtained,meanwhile the discrete kalman filtering is used to improve stability of ANF,then the performance analysis of ANF frequency estimation methods at steady state is also given;thirdly,the frequency estimation results of ANF are acquired.The impacts of the parameters on the accuracy of ANF for frequency estimation are discussed.Consequently,the calculated experiment results are provided to confirm the effectiveness and correctness of the algorithm.关键词：adaptive notch filter;frequency estimation;error function;Kalman filtering2|2|3更新时间：2025-07-16
- 摘要：Tag hierarchies generated from social tagging systems can be used in various fields.Current research works mainly focus on the detection of tag relations,but pay much less attention on how to generate high quality tag hierarchy with these relations.This paper studies relation recognition and hierarchy composition methods for Web 2.0 tag hierarchy construction.By analyzing and recognizing the types of the tag relation detected by available methods,quality of tag relation is improved.Moreover,a semantic flow analysis based hierarchy composition method is proposed to acquire tag hierarchy with higher quality.Experimental results measured by various evaluation metrics have shown that by applying relation recognition and semantic flow analysis based hierarchy composition,hierarchies with higher quality with respect to other evaluated methods can be yielded.关键词：Web 2.0;social tagging;tag hierarchy;relation recognition;hierarchy composition2|2|0更新时间：2025-07-16
- 摘要：Community identification has been a hot spot and a cutting-edge topic among researchers.Since none of the present community identification methods simultaneously meets the requirements,such as lower time complexity,independence of expertise or experiences,allowance for overlapping nodes and so on,an overlapping community identification method is proposed based on topological potential theory.This method can also identify the structural holes in communities at the same time by the presented uncertainty measure of the community identity of the overlapping nodes,and its effectiveness is verified by experiments.In addition,an influence factor optimization algorithm is proposed and network fragility is discussed and prooved from the perspective of structural hole theory.关键词：network;overlapping community;structural holes;identification;topological potential;influence factor;uncertainty measure;fragility2|2|4更新时间：2025-07-16
- 摘要：This paper studies the problem of odor source localization in noise environment,and proposes a cooperative search method of multi-robot based on particle swarm optimization.In this method,a robot is defined as a particle,odor concentration detected by sensors of this robot is regarded as the fitness of this particle,and all robots form the swarm of PSO.Using an improved bare-bones PSO to lead the particles search cooperatively odor source,a dynamical statistic method is proposed to estimate noise degree of odor concentration detected by sensors;a probability domination relationship suitable to interval fitness is defined to compare particles and update the local leaders of particles.Moreover,a Gauss sampling method based on the global and local leaders is used to update the positions of particles.Finally,the proposed method is applied to two scenarios with odor sources,and experimental results confirmed its effectiveness on solving the problem of odor source localization in noise environment.关键词：odor source localization;multi-robot;particle swarm optimization;noise;probability domination2|2|5更新时间：2025-07-16
- 摘要：Previous methods are difficult to tackle a many-objective optimization problem since it contains many objectives.A set-based evolutionary algorithm was proposed to effectively solve the above problem in this study.In the proposed method,the original optimization problem was first transformed into a tri-objective one by taking such indicators as hyper-volume,distribution and spread as three new objectives;thereafter,a set-based Pareto dominance relation was defined,and a fitness function reflecting a user's preference was designed;additionally,set-based evolutionary strategies were suggested.The proposed method was applied to four benchmark many-objective optimization problems and compared with the other two methods.The experimental results show its advantages.关键词：evolutionary algorithm;many-objective optimization;set-based evolution;user preference3|3|20更新时间：2025-07-16
- 摘要：Aiming at remote sensing image data having properties of high-dimension and small amount of labeled samples,a dimensionality reduction algorithm called semi-supervised discriminative locality alignment based on graph is proposed.At first,a similarity graph and a penalty graph are constructed according to all labelled and unlabelled samples.Then,based on the principle that the dispersion between neighbours of the same class is minimum and that the dispersion between neighbours of different class is maximum,optimization goals on the similarity graph and on the penalty graph are respectively determined.At last,an optimal mapping from the high-dimensional space to a low-dimensional subspace can be obtained by simultaneously optimizing the two objective functions,which makes the dimensionality reduction of high-dimensional remote sensing images realized.Experimental results on ROSIS hyperspectral data show that the proposed algorithm can effectively improved the overall accuracy and Kappa coefficient of high-dimensional remote sensing images.关键词：semi-supervised;discriminative locality alignment;graph;dimensionality reduction;remote sensing image2|2|3更新时间：2025-07-16
- 摘要：Central Force Optimization(CFO)is a new deterministic multi-dimensional search metaheuristic based on the metaphor of gravitational kinematics.CFO is a deterministic algorithm that explores a decision space by"flying"a group of probes whose trajectories are governed by Newton's laws.But it may be local trapping.This paper makes a thorough research on the probes move governed by the equations of gravitational motion through the Celestial Mechanics,establishing the relationship between CFO algorithm and Celestial Mechanics,using the perturbation theory of Celestial Mechanics to improve CFO algorithms and deducing the new iterative equation.Finally,simulation results show that CFO based on perturbation theory avoids local trap.The enhanced algorithm has great advantage of convergence property and robustness compared to stochastic algorithms.关键词：probe;central force optimization;deterministic algorithm;perturbation theory2|2|1更新时间：2025-07-16
- 摘要：In this paper,a class of hybrid bidirectional associative memory neural networks with proportional delays is studied.In virtue of Brouwer fixed point theorem,the existence and uniqueness of equilibrium of the system are proved.The transformation transforms the neural networks with proportional delays into the neural networks with unequal constant delays and variable coefficients.By applying inequality techniques,a system of the quasi Halanay-type inequalities is established,and a delay-independent sufficient condition is derived for ensuring the global exponential stability of equilibrium of the system.And two examples are given to illustrate the effectiveness of obtained results.关键词：bidirectional associative memory;neural networks;proportional delays;Brouwer fixed point theorem;global exponential stability2|2|3更新时间：2025-07-16
- 摘要：An innovative approach of proton exchange membrane fuel cell (PEMFC) modeling based on dynamic neural networks is proposed to improve approximating and self-adaptive ability of the existing PEMFC models.To evaluate the rationality of networks structure,sensitivity analysis (SA) of the model output was introduced.The hidden nodes were pruned or inserted according to the result of SA to optimize the networks structure and parameters,so that the networks could adapt the PEMFC data processing automatically.The approach was validated using operation data from a commercial dual-system fuel cell test platform.The result shows the proposed PEMFC model with more compact structure,higher accuracy and faster convergence rate compared with the common models,have the capability to be applied to engineering simulation applications.关键词：proton exchange membrane fuel cell (PEMFC);modeling;dynamic neural network;sensitivity analysis2|2|1更新时间：2025-07-16
- 摘要：This paper proposes a multidimensional (multi-mode) tensor model for the electromagnetic vector-sensor (EMVS) array to make full use of the multidimensional structure of the data.The mode-R signal subspace is defined based on this model.With the projection to the mode-R signal subspaces,a novel algorithm,which incorporates the refined signal subspace and the traditional MUSIC algorithm,is then presented.The proposed technique exploits the inherent multidimensional structure information for increased parameter estimation accuracy.Simulations show the superiority of the proposed algorithm to the traditional one.关键词：direction-of-arrival estimation;array signal processing;electromagnetic vector-sensor2|2|0更新时间：2025-07-16
- 摘要：Due to the limited energy and communication ability of nodes in Wireless Sensor Network (WSN),it is especially important to design a good routing method (protocol) for WSN in order to make sensed data be transmitted to the receiver effectively.A kind of routing protocol based on Forward-Aware Factor for Energy Balance (FAF-EBRP) is proposed in this paper.In FAF-EBRP,the next-hop node is selected according to the awareness of link weight and forward energy density.Furthermore,a spontaneous reconstruction mechanism for local topology is designed additionally.Based on many experiments,FAF-EBRP is compared with classic LEACH and EEUC method.Experimental results show that FAF-EBRP outperforms LEACH and EEUC,which can balance the energy consumption,prolong the function lifetime of WSN.关键词：wireless sensor networks;routing protocol;forward-aware Factor;energy balance2|2|5更新时间：2025-07-16
- 摘要：Compared with traditional malicious codes detection mechanisms,detecting malicious codes in virtual desktop system faces serious performance challenge,multiple virtual desktops on a physical server conduct malicious code detection in parallel will face serious bottlenecks in the hardware devices with poor performance,such as hard disks.In this paper,we propose a malicious code detection mechanism for virtual desktop system,a malicious code detection mechanism based on mother-clone technology(MCIDS).Based on the characteristics of virtual desktops,MCIDS is designed to reduce the scope of mal-code detection by system image network storage clone technique and the mal-code detection engine deployed in network storage system,and this method effectively decreases the amount of disk IO operation caused by the detection of malicious codes,so that the performance of the system is improved greatly;In addition,MCIDS overcomes the semantic gap problem which often exists in traditional out-of-the-box security detection mechanisms.Experiments conducted on the prototype show that our method is technicallyfeasibleand the performance of MCIDS is better than other methods.关键词：malicious code detection;virtual desktop;network storage;storage clone2|2|1更新时间：2025-07-16
- 摘要：In this article,we got the 8- intersection model by extending the classic 4-intersection model,to represent the topological relation among three simple regions,and we specially obtained 109 kinds of topological relations among three simple regions.By researching 109 kinds of topological relations among three simple regions,we established the reasoning system of topological relation and gave the composite table.Further,we gave the conceptual neighborhood graph of 109 kinds of topological relations.The proposed topological relation model can be applied to qualitatively simulate the spatial relations between robots with two designated obstacles,which is useful to some extent in developing robot obstacle avoidance mechanism.关键词：qualitative spatial reasoning;three simple regions;robot obstacle avoidance2|2|0更新时间：2025-07-16
- 摘要：Transactional memory is an attractive technology to improve programmability of multi-core processors.However,there still exist challenges for hardware transactional memory including efficient transaction nesting.To support closed nesting efficiently without increasing hardware complexities significantly,this paper proposes a CPR scheme which supports conditional partial rollback on conflict.In stead of rolling back to the outermost transaction as in commonly-used flattening model,the CPR scheme just rolls back to the conflicted transaction itself or one of its outer-level transactions if given condition is satisfied.By adding a series of hardware bits in transactional buffer to record read/write status of each nested transaction,the CPR scheme only maintains a global data set for all of the nested transactions rather than independent data set for each nested transaction as in nested LogTM.Evaluation results show that the CPR scheme achieves similar performance with the nested LogTM,and is better than the flattening model.关键词：transactional memory;chip multiprocessor;programmability;transaction nesting;partial rollback2|2|0更新时间：2025-07-16
- 摘要：Formal specification techniques are very useful and important for improving quality and productivity of software.But acquisition of formal software specification is a quite difficult task in requirement engineering.The research objective aims to the important problem about automating conversion from problem requirement into a formal specification.This paper studies the automatic generation system from structural requirement language (SRL) into formal specification-Radl and its high reliability theory.We design a controlled natural language-SRL to describe the problem requirement.Using rule-based method,convert SRL into Radl by analysis-transformation-synthesis three stages.Under the guidance of the rule-based generation method,we design and implement the generation system SRLtoRadl from SRL to Radl.Furthermore,establish the generation process semantic model of SRLtoRadl using category theory framework.Practical effects manifest it can effectively generate formal software specification of high quality.关键词：structural requirement language;formal software specification;automatic generation system;high reliability;category semantics3|2|3更新时间：2025-07-16
- 摘要：To clarify secondary electron (SE) yield and current characteristics of dielectrics due to low-energy electron beam irradiation,we propose an electron scattering,trapping,transport and self-consistent numerical model by combining the Monte Carlo method and the finite difference method.By establishing an improved SE detection platform,we measure the emission SE current of dielectric samples.Results show that,comparing with the impulse electron beam irradiation,the SE yield will decrease evidently under the continuous electron beam irradiation.With irradiation,the SE current and yield reduce to a stable value gradually.Moreover,the SE yield varies slightly with electron beam current,but increases with the increase in the sample thickness.The results provide the theoretical guidance to improve the imaging quality and suppress the charging effect in modern scanning electron microscopy and a new thought for the parameter measurement of dielectrics according to SE characteristics.关键词：dielectrics;electron beam irradiation;secondary electron current;secondary electron yield2|2|5更新时间：2025-07-16
- 摘要：In cloud computing,clients put the large data files on the untrusted cloud storage server.As clients no longer physically possess the storage of their data,how to efficiently verify the correctness of outsourced cloud data becomes a big challenge for data storage security in cloud computing.In order to solve the problem of data integrity checking,many schemes are proposed.We first propose the notion of the known-proofs forgery attack,i.e.,the adversary who has a certain number of proofs can forge a new legal proof.We point out that some known schemes cannot resist the known-proofs forgery attack.After that we propose an improved data integrity checking protocol with full data dynamics and public verifiability for cloud storage by manipulating rank-based authenticated skip list.关键词：cloud storage;integrity authentication;public auditability;data dynamics4|2|8更新时间：2025-07-16
- 摘要：Based on discriminative component analysis(DCA)algorithm,a local discriminative component analysis(LDCA)algorithm for facial expression recognition is proposed.First,LDCA algorithm chooses a number of nearest neighbors of a test sample from a training set to capture the local data structure.Then,the facial expression features of each testing sample are extracted by maximizing the total variance between the discriminative data chunklets and minimizing the total variance of data instances in the same chunklets.The experimental results on several representative facial expression datasets show that proposed method not only improves the recognition rate of DCA algorithm,but also exhibits strong robustness.关键词：facial expression recognition;discriminative component analysis;chunklet2|3|9更新时间：2025-07-16
- 摘要：In networked multi-sensor systems,the measurements sampled by sensors are transmitted to the fusion center through communication network with various time-varying delay phenomenons.The existing methods on the filtering problems of these systems either lost the real time property of the filtering process or lost the optimality of the filtering accuracy.In this paper,a real-time recursive optimal sequential fusion filter is proposed in the sense of linear minimum mean square error (LMMSE),based on the relationship of system states at different sampled instants and a novel noise estimation method.Firstly,based on the relationship of system states at different sampled instants,the measurement received by the fusion center at different time,is re-modeled as a pseudo measurement of the current state.Secondly,a noise estimation method is presented to estimate the gain noises in the pseudo measurement and solve the filtering gain matrix in the filtering process.Thirdly,the optimal estimate of the current state is obtained based on the re-modeled pseudo measurement and the solved filtering gain matrix.A real-time recursive optimal sequential fusion filter is obtained to deal with all the received measurement in the current fusion period according to the above proposed method.Finally,a simulation example is exploited to show the effectiveness of the proposed method.关键词：networked multi-sensor system;fusion filtering;linear minimum mean square error;noise estimation2|2|0更新时间：2025-07-16
- 摘要：In this paper,we propose a Directional Antenna based RouTing (DART) protocol that utilizes direction information to route packets.The direction information is more robust to mobility than the path information.The overhead scales linearly with the network size and does not vary with mobility and network loads.The simulations show that DART can offer a high packet delivery ratio in scenarios with high mobility.关键词：mobile ad-hoc network;routing;directional antenna;high mobility;Bloom filter2|2|0更新时间：2025-07-16
- 摘要：To improve the efficiency under high false alarms probability conditions,an infrared dim point target trajectory detection algorithm based on short trajectories detection is proposed in this paper.The short trajectories are detected in consecutive frames at first,and then the trajectory association which builds a new trajectory depends on the result of short trajectory is applied to detect the target trajectory.The relationship between false alarms probability and detection probability is deduced,and the detection performance is proved to be better than algorithm based on trajectory association combining with segmentation in single frame.The experimental results indicate that the amount of invalid trajectories can be decreased effectively while the target trajectory is being detected accurately,and the efficiency of target detection is improved.关键词：dim point target;trajectory detection;short trajectory;trajectory association3|3|0更新时间：2025-07-16
- 摘要：Pixel reset circuit is an important component of CMOS image sensor,whose characteristics affect the image quality directly.The performances of CMOS image sensor,such as dynamic range,anti-blooming,image lag and non-linearity,are analyzed.This paper also discusses the methods to improve performance through reset circuit.In this paper,two kinds of hard reset circuit with anti-blooming circuit are designed,one is the use of conventional cross-coupled configuration to implement reset level shift,the other is based on improved latch configuration with adding compensation transistor of threshold value,both schemes with different advantages and disadvantages adapt for different applications.The simulations reveal that both circuits implement can enhance dynamic range by 2dB~3dB,increase the ability of anti-blooming,and remove image lag and non-linearity at low-light level.关键词：CMOS image sensor;hard reset;dynamic range;anti-blooming;image lag;non-linearity3|2|5更新时间：2025-07-16
- 摘要：This paper proposes a broadband omnidirectional circularly polarized (CP) antenna based on a loop-dipole configuration.The antenna consists of four pairs of titled dipoles and a broadband feeding network.The four pairs of titled dipoles are wrapped around a cylinder.Each pair of titled dipoles includes a driven dipole and a parasitic element which is introduced to enhance the bandwidth.The feeding network is composed of four broadband baluns and an impedance matching circuit.Experimental results show that this CP antenna has a 15-dB return loss bandwidth of 31%(1.68-2.31GHz) and a 3-dB axial ratio bandwidth of 30%(1.7-2.3GHz).The gain variation in the horizontal plane is less than 1dB关键词：omnidirectional antenna;circularly polarized antenna;broadband antenna4|3|2更新时间：2025-07-16
- 摘要：Recording device identification is a kind of blind digital audio forensic technique,which extracts digital evidence of device mechanism involved in the generation of the speech recording by analyzing the acoustic signal.This paper proposes a recording device identification algorithm which is based on improved PNCC feature and two-step discriminative training.Due to the fact that silence periods contain the device information and is not affected by speaker and texture factors,this paper extracts improved PNCC from silence periods,which uses long term analysis to remove the effect of background noise.GMM-UBM is set as the baseline system,which is improved by two steps discriminative training.The experimental result indicates that the average accuracy of recording device identification on 30 devices is 90.23%;for 15 inset and 15 outset devices testing,the EER is 15.17% and ACC is 96.65%,which proves the effectiveness of the proposed algorithm.关键词：digital audio forensics;recording device identification;GMM-UBM;discriminative training;PNCC2|2|7更新时间：2025-07-16
- 摘要：In this paper,analysis of three-port T-junction based on the admittance matrix is presented.This method extracts parameters of the equivalent circuit model with high accuracy in ultra wideband.In order to control the effect of the parasitic capacitance,two improved T-junctions with concave and convex segments are proposed.The effect in the equivalent circuit model and parasitic capacitance due to different connection ways of three-port T-junction is also investigated.Then the improved T-junctions are applied to design a high-performance branch-line coupler with center frequency of 12GHz.The return loss and isolation are both better than -26dB at the center frequency,while the total insertion losses are below 1 dB and amplitude imbalance is within 0.1dB.关键词：T-junction;branch-line coupler;admittance matrix;equivalent circuit model2|3|1更新时间：2025-07-16
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