毫米波/亚毫米波临边探测仪准光技术

Quasi-optical technology in millimeter/sub-millimeter limb sounder

摘要:

毫米波/亚毫米波临边探测仪中的辐射计通常需要工作在多个频段，如多频段共馈源，则其带宽往往不能达到要求。当多个探测频段共用一个主反射镜，采用准光学技术实现探测频率分离，则可以节省很大的空间。准光极化线栅和准光频率选择器相配合用来分离频率范围在 118 GHz～340 GHz 的4个频带，准光极化线栅是一个准光功率分配/合成器，将4个频段的信号分为(183 GHz/240 GHz)和(118 GHz/340 GHz)2组信号。准光频率选择器是一个高频频率选择表面，可以将高频段的电磁波透射，低频段的电磁波反射。反射和透射的电磁波分别进入2个频段的接收模块，实现信号的接收。本文利用HFSS仿真软件对周期单元的结构参数进行仿真优化，并通过仿真结果完成了准光极化线栅和准光频率选择器的技术实现。实测结果与毫米波/亚毫米波临边探测仪的设计要求一致。

Abstract:

Millimeter/sub-millimeter limb sounder plays an important role in atmospheric science, environmental science and global climate change research. Millimeter/sub-millimeter limb sounding radiometer usually needs to operate in multiple frequency bands, such as multi-band of feed，therefore its bandwidth can not meet the requirements usually. When multiple detection bands share a primary mirror, using quasi-optical technology to achieve the detection of frequency separation can save a lot of space. The combination of quasi-optical polarization wire grid and quasi-optical frequency selector can be used to separate four bands of frequency ranging from 118 GHz to 340 GHz. Quasi-optical polarization wire grid is a quasi-optical power divider/combiner，which separates the four bands signals into 183 GHz/240 GHz and 118 GHz/340 GHz; while quasi-optical frequency selector is a high frequency selective surface, which can transmit high-frequency electromagnetic waves and reflect low frequency electromagnetic waves. Reflected and transmitted electromagnetic waves enter into two receiving modules to achieve signal reception. In this paper, the structural parameters are simulated and optimized in HFSS for the periodic unit. The quasi-optical polarization wire grid and quasi-optical frequency selector technology are implemented according to simulation results. The practically measured results are consistent to the design requirements of millimeter/sub-millimeter limb sounding instrument.