In order to better understand the variation mechanism of ozone abundance in the middle atmosphere, the simultaneous monitoring of ozone and other minor molecular species, which are related to ozone depletion, is the most fundamental and critical method. A waveguide-type multiplexer was developed for the expansion of the observation frequency range of a millimeter-wave spectroradiometer, for the simultaneous observation of multiple molecular spectral lines. The proposed multiplexer contains a cascaded four-stage sideband-separating filter circuit. The waveguide circuit was designed based on electromagnetic analysis, and the pass frequency bands of stages 1–4 were 243–251 GHz, 227–235 GHz, 197–205 GHz, and 181–189 GHz. The insertion and return losses of the multiplexer were measured using vector network analyzers, each observation band was well-defined, and the bandwidths were appropriately specified. Moreover, the receiver noise temperature and the image rejection ratio (IRR) using the superconducting mixer at 4 K were measured. As a result, the increase in receiver noise due to the multiplexer compared with that of only the mixer can be attributed to the transmission loss of the waveguide circuit in the multiplexer. The IRRs were higher than 25 dB at the center of each observation band. This indicates that a high and stable IRR performance can be achieved by the waveguide-type multiplexer for the separation of sideband signals.

为了更好地理解中层大气中臭氧丰度的变化机理，与臭氧消耗有关的同时监测臭氧及其他小分子物质是最基本，最关键的方法。开发了一种波导型多路复用器，以扩展毫米波光谱仪的观察频率范围，以便同时观察多条分子光谱线。拟议的多路复用器包含一个级联的四级边带分离滤波器电路。波导电路是基于电磁分析而设计的，1-4级的通过频带为243-251 GHz，227-235 GHz，197-205 GHz和181-189 GHz。使用矢量网络分析仪测量了多路复用器的插入和回波损耗，每个观察带均已明确定义，并且带宽已适当指定。此外，使用超导混合器在4 K下测量了接收机噪声温度和镜像抑制比（IRR）。结果，与仅混频器相比，由复用器引起的接收机噪声的增加可以归因于复用器中的波导电路的传输损耗。在每个观察带的中心，IRR均高于25 dB。这表明通过用于分离边带信号的波导型多路复用器可以实现高而稳定的IRR性能。与仅混频器相比，由复用器引起的接收机噪声的增加可归因于复用器中波导电路的传输损耗。在每个观察带的中心，IRR均高于25 dB。这表明通过用于分离边带信号的波导型多路复用器可以实现高而稳定的IRR性能。与仅混频器相比，由复用器引起的接收机噪声的增加可归因于复用器中波导电路的传输损耗。在每个观察带的中心，IRR均高于25 dB。这表明通过用于分离边带信号的波导型多路复用器可以实现高而稳定的IRR性能。