Dual polarized and balanced receivers at millimeter and submillimeter wavelengths
Dual polarized and balanced receivers at millimeter and submillimeter wavelengths
复制标题
毫米和亚毫米波长的双偏振和平衡接收器
DOI：
10.7907/rmvx-0619
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发表时间：
2000
影响因子：
4.3
通讯作者：
G. Chattopadhyay
中科院分区：
文献类型：
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作者：
G. Chattopadhyay
近年来，毫米波和亚毫米波接收机的巨大进步源于超导体绝缘体超导体（SIS）混频器的发展，该混频器现在提供70 GHz至1 THz的卓越性能。为了在这些频率上进一步增加接收器的灵敏度，需要使用双极化和平衡接收器。当同时接收两个极化时，信噪比（SNR）有2的平方根的改善。平衡混频器通过抑制本地振荡器（LO）幅度调制（AM）噪声和抑制LO热噪声来提高接收机的灵敏度。本论文描述了毫米波和亚毫米波低噪声双极化平衡接收机混频器和器件的设计、制作和性能。准光接收机采用了一种新的交叉槽天线的硅超半球形透镜，两个结调谐电路，铌三层结，和IF电路包含一个集总元件180度的混合。天线有四个馈电点，每个极化两个，每个馈电点耦合到一个双结SIS混频器。对于双偏振操作，混频器以这样的方式安装，即单个LO可以泵浦两个偏振的结。对于平衡接收器，LO和RF信号使用线栅偏振器以正交偏振耦合到混频器。针对波导双极化接收机，设计了一种中等宽带的隔片正交模换能器（OMT），并给出了毫米波段的实验结果。研究了宽带鳍线OMT在毫米波段的应用，给出了X波段鳍线OMT的实验结果。
Dramatic advances in millimeter and submillimeter wave receivers in recent years have resulted from the development of superconductor insulator superconductor (SIS) mixers, which now offer unsurpassed performance from 70 GHz to 1 THz. To increase the sensitivity of the receivers further at these frequencies, one needs to use dual-polarized and balanced receivers. When both the polarizations are received simultaneously, there is a square root of two improvement in the signal to noise ratio (SNR). Balanced mixers improve the sensitivity of receivers by suppressing local oscillator (LO) amplitude modulation (AM) noise and rejecting LO thermal noise. This thesis describes the design, fabrication and performance of mixers and components for low noise dual-polarized and balanced receivers at millimeter and submillimeter wavelengths both in quasi-optical and waveguide configurations. The quasi-optical receiver utilizes a novel cross-slot antenna on a silicon hyperhemispherical lens, two junction tuning circuits, niobium trilayer junctions, and an IF circuit containing a lumped element 180 degree hybrid. The antenna has four feed points, two for each polarization; and each feed point is coupled to a two-junction SIS mixer. For dual polarization operation, the mixer is mounted in such a way that a single LO can pump the junctions for both the polarizations. For the balanced receiver, the LO and the RF signals are coupled to the mixer in orthogonal polarizations using a wire-grid polarizer. For waveguide dual polarization receivers, a moderately broadband septum ortho-mode transducer (OMT) is designed and experimental results are presented at millimeter wavelengths. Broadband finline OMTs are investigated for possible use at millimeter wavelengths, and experimental results of a finline OMT is presented at X-band.