High performance high-temperature superconducting (HTS) filters have been designed and constructed for satellite application. The filters are actually a superconducting integration of an 8-pole band-pass filter with a...High performance high-temperature superconducting (HTS) filters have been designed and constructed for satellite application. The filters are actually a superconducting integration of an 8-pole band-pass filter with an adjustable band-stop filter onto a single piece of LaAlO3 substrate (with dimension of 0.5×45×20 mm3). Typical results of the filters, i.e., Filters A (made by YBCO) & B (made by TBCCO) will be reported. The measured responses of Filter A showed excellent specifications, e.g., an insertion loss less than 0.1 dB, a return loss better than -22.5 dB in pass-band, band-edge steepness greater than 12 dB/MHz and out-of-band rejection at a certain band deeper than -110 dB. To satisfy the requirement of rocket launch and space operation, three filters of the above design have undergone mechanical environmental simulation tests for space qualification. Detailed analysis of the response curves of Filter B measured before and after the tests showed that no noticeable change in the per-formance can be found. All the filters passed the rigorous ground simulation tests, which is the first time in China for HTS devices and provided a solid foundation for satellite applications of high-temperature superconductors in the near future.展开更多
The acoustic field distributions and the convergent beams generated by the planar-structure Fresnel zone transducers on solid surface are investigated. Because only 0 and 180 degree phase transducers are used, an imag...The acoustic field distributions and the convergent beams generated by the planar-structure Fresnel zone transducers on solid surface are investigated. Because only 0 and 180 degree phase transducers are used, an imaging system with the Fresnel zoom lens could work at very high frequency, which overcomes the frequency limit of the traditional phased array acoustic imaging system. Simulation results are given to illustrate the acoustic field distributions along the focal axis and the whole plane as well. Based on the principle of scanning of the focus with the change of frequency for the excited signal, an experimental imaging system is also built. Acoustic Fresnel zone transducers are fabricated at center frequency of 400 MHz. Measurements and detections of the known hole flaws at different depths of the fused quartz sample are presented to show that the imaging system with Fresnel zoom lens could move its focus by only changing the frequency of the excited signal.展开更多
A high Q HTS cavity resonator with resonating frequency f0=5.624 GHz was fabricated using high quality HTS film and high purity sapphire. The unloaded quality factor of the HTS resonator was as high as QU=1.09×10...A high Q HTS cavity resonator with resonating frequency f0=5.624 GHz was fabricated using high quality HTS film and high purity sapphire. The unloaded quality factor of the HTS resonator was as high as QU=1.09×106 at the nitrogen temperature, 77 K. A HTS local oscillator combining the high Q cavity resonator with a C-band low noise GaAs HEMT amplifier was then designed and constructed. The phase noise of the oscillator, measured by a HP 3048A noise measurement system, is -134 dBc/Hz at 10 kHz offset when the temperature is 77 K. This result is close to the best level reported by other groups in the world.展开更多
基金the Chinese Academy of Sciences (KJCX2-SW-W01)Beijing Mu-nicipal Science & Technology Commission (H010410050111)+1 种基金the Ministry of Sci-ence and Technology of China (2002AA306181)the National Natural Science Foundation of China (Grant No.10474127)
文摘High performance high-temperature superconducting (HTS) filters have been designed and constructed for satellite application. The filters are actually a superconducting integration of an 8-pole band-pass filter with an adjustable band-stop filter onto a single piece of LaAlO3 substrate (with dimension of 0.5×45×20 mm3). Typical results of the filters, i.e., Filters A (made by YBCO) & B (made by TBCCO) will be reported. The measured responses of Filter A showed excellent specifications, e.g., an insertion loss less than 0.1 dB, a return loss better than -22.5 dB in pass-band, band-edge steepness greater than 12 dB/MHz and out-of-band rejection at a certain band deeper than -110 dB. To satisfy the requirement of rocket launch and space operation, three filters of the above design have undergone mechanical environmental simulation tests for space qualification. Detailed analysis of the response curves of Filter B measured before and after the tests showed that no noticeable change in the per-formance can be found. All the filters passed the rigorous ground simulation tests, which is the first time in China for HTS devices and provided a solid foundation for satellite applications of high-temperature superconductors in the near future.
文摘The acoustic field distributions and the convergent beams generated by the planar-structure Fresnel zone transducers on solid surface are investigated. Because only 0 and 180 degree phase transducers are used, an imaging system with the Fresnel zoom lens could work at very high frequency, which overcomes the frequency limit of the traditional phased array acoustic imaging system. Simulation results are given to illustrate the acoustic field distributions along the focal axis and the whole plane as well. Based on the principle of scanning of the focus with the change of frequency for the excited signal, an experimental imaging system is also built. Acoustic Fresnel zone transducers are fabricated at center frequency of 400 MHz. Measurements and detections of the known hole flaws at different depths of the fused quartz sample are presented to show that the imaging system with Fresnel zoom lens could move its focus by only changing the frequency of the excited signal.
文摘A high Q HTS cavity resonator with resonating frequency f0=5.624 GHz was fabricated using high quality HTS film and high purity sapphire. The unloaded quality factor of the HTS resonator was as high as QU=1.09×106 at the nitrogen temperature, 77 K. A HTS local oscillator combining the high Q cavity resonator with a C-band low noise GaAs HEMT amplifier was then designed and constructed. The phase noise of the oscillator, measured by a HP 3048A noise measurement system, is -134 dBc/Hz at 10 kHz offset when the temperature is 77 K. This result is close to the best level reported by other groups in the world.
