In this paper, based on a tangential interpolation function and an adaptively increasing penalty-factor strategy(TIPS), a novel parameterization method with a self-penalization scheme aimed for the topology optimizati...In this paper, based on a tangential interpolation function and an adaptively increasing penalty-factor strategy(TIPS), a novel parameterization method with a self-penalization scheme aimed for the topology optimization of metallic antenna design is proposed. The topology description is based on the material distribution approach.The proposed tangential interpolation function aims to associate the material resistance with design variables, in which the material resistance is expressed in the arctangent scale and the arctangent resistance is interpolated with the design variables using the rational approximation of material properties. During the optimization process, a strategy with an adaptively increasing penalty factor is used to eliminate the remaining gray scale elements, as illustrated in examples,in the topology optimization based on the proposed tangential interpolation function. Design results of typical examples express the effectiveness of the proposed TIPS parameterization.展开更多
Design of ultra-wideband antennas is challenging in the stringent requirements that are often conflicting to achieve a wide impedance bandwidth while maintaining high radiation efficiency, uniform gain and compact siz...Design of ultra-wideband antennas is challenging in the stringent requirements that are often conflicting to achieve a wide impedance bandwidth while maintaining high radiation efficiency, uniform gain and compact size. A Multiple-Input Multiple-Output (MIMO) antenna system can enhance the overall antenna performance but at having to overcome new challenges such as reducing the mutual coupling and the correlation between the elements. A printed circular disc compact planar antenna is selected in this work due to its UWB performance and compact size for the MIMO antenna system. A parametric analysis is carried out to achieve an optimal design. The system developed consists of two elements with an overall size of 59 × 27 mm. The designed antenna system operates over the whole of the UWB bandwidth from 3.1 to 10.6 GHz with radiation efficiency up to 85% and reflection coefficients less that ?10 dB. The envelope correlation is less than ?60 dB throughout the UWB band while the diversity gain approaches 10 throughout the entire UWB bandwidth and Total Active Reflection Coefficient (TARC) between the antenna elements is less ?11 dB. Thus the proposed MIMO antenna outperforms similar antenna systems reported in the literature.展开更多
Patch antennas are small in size and suitable for microwave transmission,so they are widely used in small portable wireless devices.Multiple patch antennas are connected together to form an array antenna.Compared with...Patch antennas are small in size and suitable for microwave transmission,so they are widely used in small portable wireless devices.Multiple patch antennas are connected together to form an array antenna.Compared with the patch antenna,the array antenna has a higher directivity gain and can achieve better transmission performance.In this project,I will test the single patch antenna first,and then move to 2×1 antenna array.Finally,built a 2×2 antenna array,test and record their performance respectively.展开更多
With the explosive growth and need for high-speed wireless communications, more and more energy is consumed to support the required quality of service. Therefore, energy efficient or green communication has become a v...With the explosive growth and need for high-speed wireless communications, more and more energy is consumed to support the required quality of service. Therefore, energy efficient or green communication has become a very hot topic under the ground of limited energy resource and environmentally friendly transmission schemes. MIMO technique is capable of reducing the transmission power thanks to its diversity and multiplexing gain. Moreover, antenna selection(AS) is an alternative to extract many of the benefits in MIMO systems with a reduced cost of complexity and power. Although many works including several survey papers have investigated AS in MIMO systems, the goal of these works is only the capacity maximization or error rate minimization, which fails to guarantee the optimality of the energy efficiency in MIMO systems. In this paper, we overview the state of the art in the AS schemes in energy efficient MIMO systems, the goal of which is to optimize the energy efficiency of the whole system. Specifically, we introduce energy efficient AS in point-to-point MIMO, cooperative MIMO, multiuser MIMO and largescale MIMO systems, respectively. Several challenging and practical issues in this area are also addressed.展开更多
Considering that perfect channel state information(CSI) is difficult to obtain in practice,energy efficiency(EE) for distributed antenna systems(DAS) based on imperfect CSI and antennas selection is investigated in Ra...Considering that perfect channel state information(CSI) is difficult to obtain in practice,energy efficiency(EE) for distributed antenna systems(DAS) based on imperfect CSI and antennas selection is investigated in Rayleigh fading channel.A novel EE that is defined as the average transmission rate divided by the total consumed power is introduced.In accordance with this definition,an adaptive power allocation(PA) scheme for DAS is proposed to maximize the EE under the maximum transmit power constraint.The solution of PA in the constrained EE optimization does exist and is unique.A practical iterative algorithm with Newton method is presented to obtain the solution of PA.The proposed scheme includes the one under perfect CSI as a special case,and it only needs large scale and statistical information.As a result,the scheme has low overhead and good robustness.The theoretical EE is also derived for performance evaluation,and simulation result shows the validity of the theoretical analysis.Moreover,EE can be enhanced by decreasing the estimation error and/or path loss exponents.展开更多
The surface accuracy of a radio telescope is directly related to its operational efficiency and detection sensitivity.This is crucial under high-frequency observation conditions,where surface shape errors need to be c...The surface accuracy of a radio telescope is directly related to its operational efficiency and detection sensitivity.This is crucial under high-frequency observation conditions,where surface shape errors need to be controlled to within 1/16 of the working wavelength.In addition,the primary reflector of large radio telescopes is subject to dynamic deformation,caused by factors such as gravity and thermal effects.This paper presents a method for detecting the surface shape of radio telescopes using radio interferometry techniques combined with active reflector adjustment technology.This enables accurate assessment and correction of surface errors,ensuring the electrical performance of the radio telescope.This study investigates the practical applications of high-precision measurement techniques,such as microwave holography,out-of-focus holography,and wavefront distortion methods at the Tianma 65 m radio telescope(TMRT).Furthermore,the study presents the construction method of gravity models at different elevation angles and demonstrates the efficacy of the active reflector model.The results of the measurements indicate that the application of these methods to the TMRT has led to a notable enhancement of the accuracy of the primary reflector and a substantial improvement in efficiency in the Q-band.Through a process of iterative measurements and adjustments,the surface shape error is ultimately reduced to 0.28 mm root mean square(RMS).展开更多
In this work,we introduce a novel Micro Circular Log-Periodic Antenna(MCLPA)optimized with an advanced Evolutionary Neural Network(ENN)algorithm,specifically designed to enhance terahertz(THz)radiation detection.By le...In this work,we introduce a novel Micro Circular Log-Periodic Antenna(MCLPA)optimized with an advanced Evolutionary Neural Network(ENN)algorithm,specifically designed to enhance terahertz(THz)radiation detection.By leveraging the adaptive capabilities of the ENN framework,the antenna design efficiency is significantly improved,enabling rapid prototyping and yielding highly optimized structures tailored for practical THz applications.Extensive characterization confirms that the proposed MCLPA achieves outstanding performance,including an ultra-broad operational bandwidth of 372 GHz(0.135-0.507 THz),a peak gain of 5.51 dBi,an optimal S-parameter(S11)of−13.68 dB,and a maximum radiation efficiency of 82.39%.In addition,the MCLPA exhibits superior sensitivity,low noise susceptibility,and fast response,which are key attributes for reliable and precise THz detection.When configured in array form,the design further enhances gain and directional responsiveness,demonstrating the scalability and deployment potential of the MCLPA.This ENN-driven MCLPA represents a significant breakthrough in THz antenna engineering,introducing a transformative design paradigm that synergistically integrates algorithmic intelligence with structural innovation.By substantially reducing design time and cost while achieving exceptional performance,the proposed ENN framework sets a new benchmark for the development of next-generation THz detection and communication systems,offering broad implications for future high-frequency technologies.展开更多
A novel frequency-selective metamaterial with negative permittivity and permeability for improving directivity and gain of a helix antenna is presented in this paper.The proposed metamaterial is composed of two Z-shap...A novel frequency-selective metamaterial with negative permittivity and permeability for improving directivity and gain of a helix antenna is presented in this paper.The proposed metamaterial is composed of two Z-shape resonators printed on opposite sides of a dielectric substrate.Two forms of multilayered cells are found to be suitable for antennas and waveguides applications.In addition,a new method of designing a metamaterial-based helix antenna is presented with high directivity and gain.A comparison on radiation properties is given between the conventional and the new metamaterial-based helix antennas.Two comparisons on radiation properties are performed:(1) the effect of proposed Z-structure on monopole,dipole,and helix antennas;(2) the effect of OE3,split-ring resonator (SRR),and proposed Z-structure unit cells on the performance of helix antennas.The results show improvement of parameters such as directivity,gain,and radiation power of the new metamaterial-based helix antenna.Therefore,the combination of Z-structure with the helix antenna shows the best performance.展开更多
基金supported by the National Natural Science Foundation of China (Grants 11332004, 11372063, and 11572073)the 111 Project (Grant B14013)
文摘In this paper, based on a tangential interpolation function and an adaptively increasing penalty-factor strategy(TIPS), a novel parameterization method with a self-penalization scheme aimed for the topology optimization of metallic antenna design is proposed. The topology description is based on the material distribution approach.The proposed tangential interpolation function aims to associate the material resistance with design variables, in which the material resistance is expressed in the arctangent scale and the arctangent resistance is interpolated with the design variables using the rational approximation of material properties. During the optimization process, a strategy with an adaptively increasing penalty factor is used to eliminate the remaining gray scale elements, as illustrated in examples,in the topology optimization based on the proposed tangential interpolation function. Design results of typical examples express the effectiveness of the proposed TIPS parameterization.
文摘Design of ultra-wideband antennas is challenging in the stringent requirements that are often conflicting to achieve a wide impedance bandwidth while maintaining high radiation efficiency, uniform gain and compact size. A Multiple-Input Multiple-Output (MIMO) antenna system can enhance the overall antenna performance but at having to overcome new challenges such as reducing the mutual coupling and the correlation between the elements. A printed circular disc compact planar antenna is selected in this work due to its UWB performance and compact size for the MIMO antenna system. A parametric analysis is carried out to achieve an optimal design. The system developed consists of two elements with an overall size of 59 × 27 mm. The designed antenna system operates over the whole of the UWB bandwidth from 3.1 to 10.6 GHz with radiation efficiency up to 85% and reflection coefficients less that ?10 dB. The envelope correlation is less than ?60 dB throughout the UWB band while the diversity gain approaches 10 throughout the entire UWB bandwidth and Total Active Reflection Coefficient (TARC) between the antenna elements is less ?11 dB. Thus the proposed MIMO antenna outperforms similar antenna systems reported in the literature.
文摘Patch antennas are small in size and suitable for microwave transmission,so they are widely used in small portable wireless devices.Multiple patch antennas are connected together to form an array antenna.Compared with the patch antenna,the array antenna has a higher directivity gain and can achieve better transmission performance.In this project,I will test the single patch antenna first,and then move to 2×1 antenna array.Finally,built a 2×2 antenna array,test and record their performance respectively.
基金supported by NSFC under grant No. 61322111 and No. 61401249the National Basic Research Program of China (973 Program) No. 2013CB336600+1 种基金Specialized Research Fund for the Doctoral Program of Higher Education (SRFDP) under Grant No. 20130002120001Chuanxin Funding, and Beijing nova program No.Z121101002512051
文摘With the explosive growth and need for high-speed wireless communications, more and more energy is consumed to support the required quality of service. Therefore, energy efficient or green communication has become a very hot topic under the ground of limited energy resource and environmentally friendly transmission schemes. MIMO technique is capable of reducing the transmission power thanks to its diversity and multiplexing gain. Moreover, antenna selection(AS) is an alternative to extract many of the benefits in MIMO systems with a reduced cost of complexity and power. Although many works including several survey papers have investigated AS in MIMO systems, the goal of these works is only the capacity maximization or error rate minimization, which fails to guarantee the optimality of the energy efficiency in MIMO systems. In this paper, we overview the state of the art in the AS schemes in energy efficient MIMO systems, the goal of which is to optimize the energy efficiency of the whole system. Specifically, we introduce energy efficient AS in point-to-point MIMO, cooperative MIMO, multiuser MIMO and largescale MIMO systems, respectively. Several challenging and practical issues in this area are also addressed.
基金partially supported by the National Natural Science Foundation of China(61571225,61271255,61232016,U1405254)the Open Foundation of Jiangsu Engineering Center of Network Monitoring(Nanjing University of Information Science and Technology)(Grant No.KJR1509)+2 种基金the PAPD fundthe CICAEET fundShenzhen Strategic Emerging Industry Development Funds(JSGG20150331160845693)
文摘Considering that perfect channel state information(CSI) is difficult to obtain in practice,energy efficiency(EE) for distributed antenna systems(DAS) based on imperfect CSI and antennas selection is investigated in Rayleigh fading channel.A novel EE that is defined as the average transmission rate divided by the total consumed power is introduced.In accordance with this definition,an adaptive power allocation(PA) scheme for DAS is proposed to maximize the EE under the maximum transmit power constraint.The solution of PA in the constrained EE optimization does exist and is unique.A practical iterative algorithm with Newton method is presented to obtain the solution of PA.The proposed scheme includes the one under perfect CSI as a special case,and it only needs large scale and statistical information.As a result,the scheme has low overhead and good robustness.The theoretical EE is also derived for performance evaluation,and simulation result shows the validity of the theoretical analysis.Moreover,EE can be enhanced by decreasing the estimation error and/or path loss exponents.
基金supported by the National Key R&D Program of China(2018YFA0404702,2019YFA0708904,2021YFC2203501)Shanghai Key Laboratory of Space Navigation and Positioning Techniques,the National Natural Science Foundation of China(12273097,11903068).
文摘The surface accuracy of a radio telescope is directly related to its operational efficiency and detection sensitivity.This is crucial under high-frequency observation conditions,where surface shape errors need to be controlled to within 1/16 of the working wavelength.In addition,the primary reflector of large radio telescopes is subject to dynamic deformation,caused by factors such as gravity and thermal effects.This paper presents a method for detecting the surface shape of radio telescopes using radio interferometry techniques combined with active reflector adjustment technology.This enables accurate assessment and correction of surface errors,ensuring the electrical performance of the radio telescope.This study investigates the practical applications of high-precision measurement techniques,such as microwave holography,out-of-focus holography,and wavefront distortion methods at the Tianma 65 m radio telescope(TMRT).Furthermore,the study presents the construction method of gravity models at different elevation angles and demonstrates the efficacy of the active reflector model.The results of the measurements indicate that the application of these methods to the TMRT has led to a notable enhancement of the accuracy of the primary reflector and a substantial improvement in efficiency in the Q-band.Through a process of iterative measurements and adjustments,the surface shape error is ultimately reduced to 0.28 mm root mean square(RMS).
基金support from the Natural Sciences and Engineering Research Council of Canada(NSERC)and the Micro-Nano Technology(MNT)program facilitated by CMC Microsystems.
文摘In this work,we introduce a novel Micro Circular Log-Periodic Antenna(MCLPA)optimized with an advanced Evolutionary Neural Network(ENN)algorithm,specifically designed to enhance terahertz(THz)radiation detection.By leveraging the adaptive capabilities of the ENN framework,the antenna design efficiency is significantly improved,enabling rapid prototyping and yielding highly optimized structures tailored for practical THz applications.Extensive characterization confirms that the proposed MCLPA achieves outstanding performance,including an ultra-broad operational bandwidth of 372 GHz(0.135-0.507 THz),a peak gain of 5.51 dBi,an optimal S-parameter(S11)of−13.68 dB,and a maximum radiation efficiency of 82.39%.In addition,the MCLPA exhibits superior sensitivity,low noise susceptibility,and fast response,which are key attributes for reliable and precise THz detection.When configured in array form,the design further enhances gain and directional responsiveness,demonstrating the scalability and deployment potential of the MCLPA.This ENN-driven MCLPA represents a significant breakthrough in THz antenna engineering,introducing a transformative design paradigm that synergistically integrates algorithmic intelligence with structural innovation.By substantially reducing design time and cost while achieving exceptional performance,the proposed ENN framework sets a new benchmark for the development of next-generation THz detection and communication systems,offering broad implications for future high-frequency technologies.
基金Project (No.8711109001) supported by the Office of Brilliant Talents at Semnan University,Iran
文摘A novel frequency-selective metamaterial with negative permittivity and permeability for improving directivity and gain of a helix antenna is presented in this paper.The proposed metamaterial is composed of two Z-shape resonators printed on opposite sides of a dielectric substrate.Two forms of multilayered cells are found to be suitable for antennas and waveguides applications.In addition,a new method of designing a metamaterial-based helix antenna is presented with high directivity and gain.A comparison on radiation properties is given between the conventional and the new metamaterial-based helix antennas.Two comparisons on radiation properties are performed:(1) the effect of proposed Z-structure on monopole,dipole,and helix antennas;(2) the effect of OE3,split-ring resonator (SRR),and proposed Z-structure unit cells on the performance of helix antennas.The results show improvement of parameters such as directivity,gain,and radiation power of the new metamaterial-based helix antenna.Therefore,the combination of Z-structure with the helix antenna shows the best performance.
