In this paper, we propose an ultra-wideband reflective linear cross-polarization converter based on anisotropic metasurface. Its unit cell is composed of a square-shaped resonator with intersectant diagonal and metall...In this paper, we propose an ultra-wideband reflective linear cross-polarization converter based on anisotropic metasurface. Its unit cell is composed of a square-shaped resonator with intersectant diagonal and metallic ground sheet separated by dielectric substrate. Simulated results show that the converter can generate resonances at four frequencies under normal incident electromagnetic（EM） wave, leading to the bandwidth expansion of cross-polarization reflection. For verification,the designed polarization converter is fabricated and measured. The measured and simulated results agree well with each other, showing that the fabricated converter can convert x- or y-polarized incident wave into its cross polarized wave in a frequency range from 7.57 GHz to 20.46 GHz with a relative bandwidth of 91.2%, and the polarization conversion efficiency is greater than 90%. The proposed polarization converter has a simple geometry but an ultra wideband compared with the published designs, and hence possesses potential applications in novel polarization-control devices.展开更多
An ultrathin micro-split Jerusalem-cross metasurface is proposed in this paper, which can efficiently convert the linear polarization of electromagnetic （EM） wave into the circular polarization in ultra-wideband. By...An ultrathin micro-split Jerusalem-cross metasurface is proposed in this paper, which can efficiently convert the linear polarization of electromagnetic （EM） wave into the circular polarization in ultra-wideband. By symmetrically employing two micro-splits on the horizontal arm （in the x direction） of the Jerusalem-cross structure, the bandwidth of the proposed device is significantly extended. Both simulated and experimental results show that the proposed metasurface is able to convert linearly polarized waves into circularly polarized waves in a frequency range from 12.4 GHz to 21 GHz, with an axis ratio better than 1 dB. The simulated results also show that such a broadband and high-performance are maintained over a wide range of incident angle. The presented polarization converter can be used in a number of areas, such as spectroscopy and wireless communications.展开更多
A kind of architecture of Time-to-Digital Converter(TDC) for Ultra-WideBand(UWB) application is presented. The proposed TDC is based on pulse shrinking, and implemented in a Field Programmable Gate Array(FPGA) device....A kind of architecture of Time-to-Digital Converter(TDC) for Ultra-WideBand(UWB) application is presented. The proposed TDC is based on pulse shrinking, and implemented in a Field Programmable Gate Array(FPGA) device. The pulse shrinking is realized in a loop containing two Programmable Delay Lines(PDLs) or a two-channel PDL. One line(channel) delays the rising edge and the other line(channel) delays the falling edge of a circulating pulse. Delay resolution of PDL is converted into a digital output code under known conditions of pulse width. This delay resolution measurement mechanism is different from the conventional time interval measurement mechanism based on pulse shrinking of conversion of unknown pulse width into a digital output code. This mechanism automatically avoids the influence of unwanted pulse shrinking by any circuit element apart from the lines. The achieved relative errors for four PDLs are within 0.80%–1.60%.展开更多
In order to solve the cross-channel signal problem caused by the uniform channelized wideband digital receiver when processing wideband signal and the problem that the sensitivity of the system greatly decreases when ...In order to solve the cross-channel signal problem caused by the uniform channelized wideband digital receiver when processing wideband signal and the problem that the sensitivity of the system greatly decreases when the bandwidth of wideband digital receiver increases,which both decrease the wideband radar signal detection performance,a new wideband digital receiver based on the modulated wideband converter(MWC)discrete compressed sampling structure and an energy detection method based on the new receiver are proposed.Firstly,the proposed receiver utilizes periodic pseudo-random sequences to mix wideband signals with baseband and other sub-bands.Then the mixed signals are low-pass filtered and downsampled to obtain the baseband compressed sampling data,which can increase the sensitivity of the system.Meanwhile,the cross-channel signal will all appear in any subbands,so the cross-channel signal problem can be solved easily by processing the baseband compressed sampling data.Secondly,we establish the signal detection model and formulate the criterion of the energy detection method.And we directly utilize the baseband compressed sampling data to carry out signal detection without signal reconstruction,which decreases the complexity of the algorithm and reduces the computational burden.Finally,simulation experiments demonstrate the effectiveness of the proposed receiver and show that the proposed signal detection method is effective in low signal-to-noise ratio(SNR)compared with the conventional energy detection and the probability of detection increases significantly when SNR increases.展开更多
In this paper,a distributed compressive spectrum sensing scheme in wideband cognitive radio networks is investigated.An analog-to-information converters（AIC） RF front-end sampling structure is proposed which use par...In this paper,a distributed compressive spectrum sensing scheme in wideband cognitive radio networks is investigated.An analog-to-information converters（AIC） RF front-end sampling structure is proposed which use parallel low rate analog to digital conversions（ADCs） and fewer storage units for wideband spectrum signal sampling.The proposed scheme uses multiple low rate congitive radios（CRs） collecting compressed samples through AICs distritbutedly and recover the signal spectrum jointly.A general joint sparsity model is defined in this scenario,along with a universal recovery algorithm based on simultaneous orthogonal matching pursuit（S-OMP）.Numerical simulations show this algorithm outperforms current existing algorithms under this model and works competently under other existing models.展开更多
针对软件无线电架构的导航接收机对模数转换器的高输入带宽、高速及低功耗的需求,通过集成低功耗宽带采样保持电路及新型非二进制权重的电容阵列数模转换器电路,采用逐次逼近型模数转换器架构,设计实现了一款射频直接采样SAR模数转换器...针对软件无线电架构的导航接收机对模数转换器的高输入带宽、高速及低功耗的需求,通过集成低功耗宽带采样保持电路及新型非二进制权重的电容阵列数模转换器电路,采用逐次逼近型模数转换器架构,设计实现了一款射频直接采样SAR模数转换器。采用55 nm CMOS工艺电路设计、版图设计、仿真及硅流片验证,测试结果表明,该ADC实现了34 dB SNDR、36 dB SFDR和1.6 GHz的模拟输入信号带宽。该ADC的版图面积为670μm×390μm,功耗为9.6 mW。展开更多
This Letter demonstrates the effectiveness of a high-speed high-resolution photonic analog-to-digital converter （PADC） for wideband signal detection. The PADC system is seeded by a high-speed actively mode locked la...This Letter demonstrates the effectiveness of a high-speed high-resolution photonic analog-to-digital converter （PADC） for wideband signal detection. The PADC system is seeded by a high-speed actively mode locked laser, and the sampling rate is multiplied via a time-wavelength interleaving scheme. According to the laboratory test, an X-band linear frequency modulation signal is detected and digitized by the PADC system. The channel mismatch effect in wideband signal detection is compensated via an algorithm based on a short-time Fourier transform. Consequently, the signal-to-distortion ratio （SDR） of the wideband signal detection is enhanced to the comparable SDR of the single-tone signal detection.展开更多
随着雷达信号处理技术的发展,对于宽带线性调频(Linear Frequency Modulation)信号发生器的需求也变得十分迫切。基于Xilinx公司的直接数字频率合成(Direct Digital frequency Synthesis,DDS)IP核和高速数模转换器(Digital-to-Analog Co...随着雷达信号处理技术的发展,对于宽带线性调频(Linear Frequency Modulation)信号发生器的需求也变得十分迫切。基于Xilinx公司的直接数字频率合成(Direct Digital frequency Synthesis,DDS)IP核和高速数模转换器(Digital-to-Analog Converter,DAC)的架构,设计了一种可实时切换参数的多相宽带线性调频信号发生器,并完成仿真和上板验证。经仿真和上板验证,该信号发生器能够根据任务要求实时切换线性调频信号的参数,生成的信号指标准确,实现方法可靠,具有一定的实用价值。展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.61471387,61271250,and 61571460)
文摘In this paper, we propose an ultra-wideband reflective linear cross-polarization converter based on anisotropic metasurface. Its unit cell is composed of a square-shaped resonator with intersectant diagonal and metallic ground sheet separated by dielectric substrate. Simulated results show that the converter can generate resonances at four frequencies under normal incident electromagnetic（EM） wave, leading to the bandwidth expansion of cross-polarization reflection. For verification,the designed polarization converter is fabricated and measured. The measured and simulated results agree well with each other, showing that the fabricated converter can convert x- or y-polarized incident wave into its cross polarized wave in a frequency range from 7.57 GHz to 20.46 GHz with a relative bandwidth of 91.2%, and the polarization conversion efficiency is greater than 90%. The proposed polarization converter has a simple geometry but an ultra wideband compared with the published designs, and hence possesses potential applications in novel polarization-control devices.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61461016 and 61661012)the Natural Science Foundation of Guangxi Zhuang Autonomous Region,China(Grant Nos.2014GXNSFAA118366,2014GXNSFAA118283,and 2015jj BB7002)the Innovation Project of Graduate Education of Guilin University of Electronic Technology,China(Grant No.2016YJCX82)
文摘An ultrathin micro-split Jerusalem-cross metasurface is proposed in this paper, which can efficiently convert the linear polarization of electromagnetic （EM） wave into the circular polarization in ultra-wideband. By symmetrically employing two micro-splits on the horizontal arm （in the x direction） of the Jerusalem-cross structure, the bandwidth of the proposed device is significantly extended. Both simulated and experimental results show that the proposed metasurface is able to convert linearly polarized waves into circularly polarized waves in a frequency range from 12.4 GHz to 21 GHz, with an axis ratio better than 1 dB. The simulated results also show that such a broadband and high-performance are maintained over a wide range of incident angle. The presented polarization converter can be used in a number of areas, such as spectroscopy and wireless communications.
基金Supported by the National High Technology Research and Development Program(No.2012AA121901)
文摘A kind of architecture of Time-to-Digital Converter(TDC) for Ultra-WideBand(UWB) application is presented. The proposed TDC is based on pulse shrinking, and implemented in a Field Programmable Gate Array(FPGA) device. The pulse shrinking is realized in a loop containing two Programmable Delay Lines(PDLs) or a two-channel PDL. One line(channel) delays the rising edge and the other line(channel) delays the falling edge of a circulating pulse. Delay resolution of PDL is converted into a digital output code under known conditions of pulse width. This delay resolution measurement mechanism is different from the conventional time interval measurement mechanism based on pulse shrinking of conversion of unknown pulse width into a digital output code. This mechanism automatically avoids the influence of unwanted pulse shrinking by any circuit element apart from the lines. The achieved relative errors for four PDLs are within 0.80%–1.60%.
基金supported by the National Natural Science Foundation of China(No.61571146)the Fundamental Research Funds for the Central Universities(HEUCF1608)
文摘In order to solve the cross-channel signal problem caused by the uniform channelized wideband digital receiver when processing wideband signal and the problem that the sensitivity of the system greatly decreases when the bandwidth of wideband digital receiver increases,which both decrease the wideband radar signal detection performance,a new wideband digital receiver based on the modulated wideband converter(MWC)discrete compressed sampling structure and an energy detection method based on the new receiver are proposed.Firstly,the proposed receiver utilizes periodic pseudo-random sequences to mix wideband signals with baseband and other sub-bands.Then the mixed signals are low-pass filtered and downsampled to obtain the baseband compressed sampling data,which can increase the sensitivity of the system.Meanwhile,the cross-channel signal will all appear in any subbands,so the cross-channel signal problem can be solved easily by processing the baseband compressed sampling data.Secondly,we establish the signal detection model and formulate the criterion of the energy detection method.And we directly utilize the baseband compressed sampling data to carry out signal detection without signal reconstruction,which decreases the complexity of the algorithm and reduces the computational burden.Finally,simulation experiments demonstrate the effectiveness of the proposed receiver and show that the proposed signal detection method is effective in low signal-to-noise ratio(SNR)compared with the conventional energy detection and the probability of detection increases significantly when SNR increases.
基金Project supported by the National Fundamental Research (Grant Nos.2009CB3020402,2010CB731803)the National Natural Science Foundation of China (Grant Nos.60702046,60832005,60972050,60632040)the Natural High-Technology Research and Development Program of China (Grant Nos.2007AA01Z267,2009AA01Z248,2009AA011802)
文摘In this paper,a distributed compressive spectrum sensing scheme in wideband cognitive radio networks is investigated.An analog-to-information converters（AIC） RF front-end sampling structure is proposed which use parallel low rate analog to digital conversions（ADCs） and fewer storage units for wideband spectrum signal sampling.The proposed scheme uses multiple low rate congitive radios（CRs） collecting compressed samples through AICs distritbutedly and recover the signal spectrum jointly.A general joint sparsity model is defined in this scenario,along with a universal recovery algorithm based on simultaneous orthogonal matching pursuit（S-OMP）.Numerical simulations show this algorithm outperforms current existing algorithms under this model and works competently under other existing models.
文摘针对软件无线电架构的导航接收机对模数转换器的高输入带宽、高速及低功耗的需求,通过集成低功耗宽带采样保持电路及新型非二进制权重的电容阵列数模转换器电路,采用逐次逼近型模数转换器架构,设计实现了一款射频直接采样SAR模数转换器。采用55 nm CMOS工艺电路设计、版图设计、仿真及硅流片验证,测试结果表明,该ADC实现了34 dB SNDR、36 dB SFDR和1.6 GHz的模拟输入信号带宽。该ADC的版图面积为670μm×390μm,功耗为9.6 mW。
基金partially supported by the National Natural Science Foundation of China(Nos.61571292and 61535006)
文摘This Letter demonstrates the effectiveness of a high-speed high-resolution photonic analog-to-digital converter （PADC） for wideband signal detection. The PADC system is seeded by a high-speed actively mode locked laser, and the sampling rate is multiplied via a time-wavelength interleaving scheme. According to the laboratory test, an X-band linear frequency modulation signal is detected and digitized by the PADC system. The channel mismatch effect in wideband signal detection is compensated via an algorithm based on a short-time Fourier transform. Consequently, the signal-to-distortion ratio （SDR） of the wideband signal detection is enhanced to the comparable SDR of the single-tone signal detection.
文摘随着雷达信号处理技术的发展,对于宽带线性调频(Linear Frequency Modulation)信号发生器的需求也变得十分迫切。基于Xilinx公司的直接数字频率合成(Direct Digital frequency Synthesis,DDS)IP核和高速数模转换器(Digital-to-Analog Converter,DAC)的架构,设计了一种可实时切换参数的多相宽带线性调频信号发生器,并完成仿真和上板验证。经仿真和上板验证,该信号发生器能够根据任务要求实时切换线性调频信号的参数,生成的信号指标准确,实现方法可靠,具有一定的实用价值。
文摘调制宽带转换器(modulated wideband converter,MWC)采样方法针对稀疏宽带信号实现了可精确重构的亚奈奎斯特采样,缓解了采样率高的压力。然而现有重构算法所需的最小通道数和采样率与理论下限值仍存在较大差距。针对该问题基于奇异值分解(singular value decomposition,SVD)和多信号分类(multiple signal classification,MUSIC)思想提出一种间接重构算法。该算法首先利用SVD思想通过降维变换在不改变未知矩阵支撑集的前提下将MWC采样模型转化为低维的多测量向量(multiple measurement vector,MMV)问题,然后利用MUSIC思想获取支撑集,最后通过伪逆实现重构。实验结果表明,与传统重构算法相比,该算法可以进一步降低采样率要求,在较少的通道数下实现高概率重构,在一定条件下,重构所需的最低通道数已接近理论下限值。
