为开发一种适用于无线通信系统且具有天线辐射特性和滤波器带外抑制特性的微带天线。采用滤波器综合设计方法,设计并制作了一种由4个半波开环谐振器、1段传输耦合线和1个型微带天线构成的滤波天线。天线通过作为导纳变换器的耦合线与滤...为开发一种适用于无线通信系统且具有天线辐射特性和滤波器带外抑制特性的微带天线。采用滤波器综合设计方法,设计并制作了一种由4个半波开环谐振器、1段传输耦合线和1个型微带天线构成的滤波天线。天线通过作为导纳变换器的耦合线与滤波器的第4阶谐振器集成在一起,充当滤波器的第5阶谐振器以实现滤波功能。仿真与测试结果表明:滤波天线的阻抗带宽为2. 39~2. 49 GHz,最大增益为3. 71 d B,带内最大增益偏差不超过0. 43 d B,带外100 MHz处增益迅速降为-5 d B并趋于稳定。该滤波天线结构简单,基板轻薄,优化了滤波器与天线的整体尺寸,降低了二者间的传输损耗,可适用于无线通信系统的射频前端。展开更多
Large area YBCO superconductive films prepared by d.c. magnetron sputtering have reached: T c>89 K, J c>3.5×10 6 A/cm 2 (77 K, 0 T), R s=0.25 mΩ, at 77.5 K, 9894 MHz. The microstructure an...Large area YBCO superconductive films prepared by d.c. magnetron sputtering have reached: T c>89 K, J c>3.5×10 6 A/cm 2 (77 K, 0 T), R s=0.25 mΩ, at 77.5 K, 9894 MHz. The microstructure analysis of the film showed it has fine monocrystalline structure and the crystalline perfectness is satisfactory. The oscillator, filter and antenna made from these films are good in performance. Therefore, YBCO superconductive films have great prospect in application.展开更多
The adaptive array antenna may be considered as a general sidelobe canceller. Directional interference suppression is based on a recursive state estimation of Kalman filter. For the stationary filter,this leads to an...The adaptive array antenna may be considered as a general sidelobe canceller. Directional interference suppression is based on a recursive state estimation of Kalman filter. For the stationary filter,this leads to an iterative solution of Wiener Hops matrix equation. The performance of sidelobe canceller are studied by computer simulation. The result of simulation shows that the sidelobe canceller may be regarded as a special case of an adaptive array atenna.展开更多
Adaptive control algorithm ls a key technlque for an adaptive array. It ls necessary to find a fastand efficient aIgorithm ror gaining rapid interrerence suppression. Convergence speed of conventional gradient-based a...Adaptive control algorithm ls a key technlque for an adaptive array. It ls necessary to find a fastand efficient aIgorithm ror gaining rapid interrerence suppression. Convergence speed of conventional gradient-based algoritkms ls extremely slow and very sensitive to elgenvalue spread of autocorrelation matrix. Thispaper presents the Kalman filtering method to adaptlve array processing. It has good transient response andachieves faster convergence speed,so it is msot su1table for complicated adaptive systems. We analyzed itsconvergence performance which proved to be related to initial value for P(0). Computer simulation by applying four elements array to null steering was carrled out. It ls shown that fast convergence needs only 2Mnumbers of iteration. The Iess the value was seIected for P(o),the slower convergence was found. Further,ifP(o) were too, small, the method would not be abIe to converge. On the other hand, bigger values of P(0)can not achieve more lmprovement in convergence per formance. Slmulation aIso discovered steady responsedenoted with SNIR dependent on the power of reference signai. These results demonstrate the validity and effectiveness 0f the Kalman type adaptlve antenna.展开更多
文摘为开发一种适用于无线通信系统且具有天线辐射特性和滤波器带外抑制特性的微带天线。采用滤波器综合设计方法,设计并制作了一种由4个半波开环谐振器、1段传输耦合线和1个型微带天线构成的滤波天线。天线通过作为导纳变换器的耦合线与滤波器的第4阶谐振器集成在一起,充当滤波器的第5阶谐振器以实现滤波功能。仿真与测试结果表明:滤波天线的阻抗带宽为2. 39~2. 49 GHz,最大增益为3. 71 d B,带内最大增益偏差不超过0. 43 d B,带外100 MHz处增益迅速降为-5 d B并趋于稳定。该滤波天线结构简单,基板轻薄,优化了滤波器与天线的整体尺寸,降低了二者间的传输损耗,可适用于无线通信系统的射频前端。
文摘Large area YBCO superconductive films prepared by d.c. magnetron sputtering have reached: T c>89 K, J c>3.5×10 6 A/cm 2 (77 K, 0 T), R s=0.25 mΩ, at 77.5 K, 9894 MHz. The microstructure analysis of the film showed it has fine monocrystalline structure and the crystalline perfectness is satisfactory. The oscillator, filter and antenna made from these films are good in performance. Therefore, YBCO superconductive films have great prospect in application.
文摘The adaptive array antenna may be considered as a general sidelobe canceller. Directional interference suppression is based on a recursive state estimation of Kalman filter. For the stationary filter,this leads to an iterative solution of Wiener Hops matrix equation. The performance of sidelobe canceller are studied by computer simulation. The result of simulation shows that the sidelobe canceller may be regarded as a special case of an adaptive array atenna.
文摘Adaptive control algorithm ls a key technlque for an adaptive array. It ls necessary to find a fastand efficient aIgorithm ror gaining rapid interrerence suppression. Convergence speed of conventional gradient-based algoritkms ls extremely slow and very sensitive to elgenvalue spread of autocorrelation matrix. Thispaper presents the Kalman filtering method to adaptlve array processing. It has good transient response andachieves faster convergence speed,so it is msot su1table for complicated adaptive systems. We analyzed itsconvergence performance which proved to be related to initial value for P(0). Computer simulation by applying four elements array to null steering was carrled out. It ls shown that fast convergence needs only 2Mnumbers of iteration. The Iess the value was seIected for P(o),the slower convergence was found. Further,ifP(o) were too, small, the method would not be abIe to converge. On the other hand, bigger values of P(0)can not achieve more lmprovement in convergence per formance. Slmulation aIso discovered steady responsedenoted with SNIR dependent on the power of reference signai. These results demonstrate the validity and effectiveness 0f the Kalman type adaptlve antenna.
