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宽带相控阵宽角扫描波束形成中,常用模拟延时线技术解决复包络偏移问题,但硬件的高代价阻碍其实际应用。本文在基于跟踪状态及发射线性调频信号的假设下,提出一种二次下变频方法实现宽带数字波束形成,本方法首先对阵元级接收数据进行模拟混频实现去斜,数字域再进行二次下变频,相位补偿后实现波束形成,最终通过傅氏变换获得散射点信息。 相似文献
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Sara Ferrara Juan P. Fernandéz-Blázquez Juan Pablo Fuenzalida Werner Rubén D. Costa 《Advanced functional materials》2023,33(24):2300350
Although protein-polymer phosphors are an emerging photon-management filter concept for hybrid light-emitting diodes, deep-red-emitting devices based on archetypal fluorescent proteins (FPs; mCherry) are still poorly performing with lifetimes <50 h under high photon-flux excitation and ambient conditions. Here, the challenge is two-fold: i) understanding the deactivation mechanism of red-emitting FP-polymer coatings and, in turn, ii) identifying the best polymer design for highly stable devices. This study first provides comprehensive photophysical/thermal/structural studies and device degradation (ambient/inert) analysis, revealing the presence of photo-induced cis–trans isomerization and the effect of oxygen and water on the deactivation of mCherry in reference polymer coatings. Based on these findings, a new bio-phosphor configuration using polyvinyl alcohol derivatives, in which crystallinity and amount of trapped water (stiffness and oxygen/moisture barriers) are easily controlled by the hydroxylation degree, is successfully achieved. Compared to the prior art, these devices significantly outperform the reference stability (>50-fold enhancement), showing a brightness loss of <5% over the first 2000 h and a final device lifetime of 2600 h. Hence, this study describes a unique rationale toward designing polymers to stabilize FPs for lighting, overpassing stability frontiers in deep-red hybrid light-emitting diodes (HLEDs) going from hours to months. 相似文献
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