用于国家球形环实验（NSTX）的Ka波段可调谐直接变频相关反射计。

A Ka-band tunable direct-conversion correlation reflectometer for NSTX.

作者信息

Kubota S, Peebles W A, Nguyen X V, Crocker N A, Roquemore A L, Holoman T, Guttadora L, Kaita R

机构信息

Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA.

出版信息

Rev Sci Instrum. 2010 Oct;81(10):10D917. doi: 10.1063/1.3490024.

DOI:10.1063/1.3490024

PMID:21033949

Abstract

The recent availability of broadband microwave quadrature mixers in the Ka-band (28-40 GHz) of frequencies has allowed the fabrication of low-cost direct-conversion detection circuits for use in the variable-frequency correlation reflectometer on the National Spherical Torus eXperiment (NSTX). The quadrature receiver in this case can be implemented as a simple homodyne circuit, without the complication of a single-sideband modulator or a feedforward tracking circuit present in more typical designs. A pair of direct-conversion receivers is coupled with broadband microwave voltage-controlled oscillators to construct a flexible dual-channel radar system with a fast frequency settling time of ∼160 μs. A detailed description of the design and a full characterization of the hardware are provided. Examples of turbulence measurements from radial and poloidal correlation reflectometry on NSTX using a poloidal array of antennas (oriented normal to the magnetic flux surfaces for conventional reflectometry) are presented.

摘要

最近在Ka波段（28 - 40GHz）频率范围内出现的宽带微波正交混频器，使得能够制造低成本的直接转换检测电路，用于国家球形环面实验（NSTX）的变频相关反射计。在这种情况下，正交接收器可以实现为一个简单的零差电路，而没有更典型设计中存在的单边带调制器或前馈跟踪电路的复杂性。一对直接转换接收器与宽带微波压控振荡器耦合，以构建一个灵活的双通道雷达系统，其频率稳定时间约为160μs。文中提供了设计的详细描述和硬件的全面特性表征。还给出了在NSTX上使用一组极向天线（垂直于传统反射计的磁通量表面定向）进行径向和极向相关反射测量的湍流测量示例。