scholarly journals Calibration of a Polarimetric Microwave Radiometer Using a Double Directional Coupler

2021 ◽  
Vol 13 (11) ◽  
pp. 2109
Author(s):  
Luisa de la Fuente ◽  
Beatriz Aja ◽  
Enrique Villa ◽  
Eduardo Artal
Keyword(s):  
Directional Coupler ◽  
Microwave Radiometer ◽  
Calibration Method ◽  
Calibration Procedure ◽  
Stokes Parameters ◽  
Microwave Background ◽  
Feed System ◽  
Polarimetric Microwave Radiometer ◽  
Full Band ◽  
Linearly Polarized

This paper presents a built-in calibration procedure of a 10-to-20 GHz polarimeter aimed at measuring the I, Q, U Stokes parameters of cosmic microwave background (CMB) radiation. A full-band square waveguide double directional coupler, mounted in the antenna-feed system, is used to inject differently polarized reference waves. A brief description of the polarimetric microwave radiometer and the system calibration injector is also reported. A fully polarimetric calibration is also possible using the designed double directional coupler, although the presented calibration method in this paper is proposed to obtain three of the four Stokes parameters with the introduced microwave receiver, since V parameter is expected to be zero for the CMB radiation. Experimental results are presented for linearly polarized input waves in order to validate the built-in calibration system.

A New Linearly Polarized Microwave Radiometer Calibration Source

2012 ◽  
Vol 500 ◽  
pp. 341-347
Author(s):  
Xin Biao Wang ◽  
Chang Zeng ◽  
Jing Li ◽  
Jing Shan Jiang
Keyword(s):  
Real Time ◽  
Microwave Radiometer ◽  
Noise Temperature ◽  
Calibration Method ◽  
Calibration Source ◽  
Radiometer Calibration ◽  
Time Calibration ◽  
Linearly Polarized ◽  
Calibration Device

This paper introduces a calibration device for microwave (millimeter and submillimeter) radiometer. The device can provide the microwave radiometer continuously variable linearly polarized noise temperature. The paper also introduces a real-time calibration method to achieve the microwave radiometer calibration, and the test of microwave radiometer sensitivity and linearity.

scholarly journals Effect Analysis of the Digital Spectrometer FFT Algorithm on THz Atmospheric Limb Sounder (TALIS) System Sensitivity

2021 ◽  
Vol 13 (15) ◽  
pp. 2921
Author(s):  
Haowen Xu ◽  
Hao Lu ◽  
Zhenzhan Wang ◽  
Wenming He ◽  
Wenyu Wang
Keyword(s):  
Chemical Constituents ◽  
Microwave Radiometer ◽  
Mean Value ◽  
Integration Time ◽  
Science Center ◽  
Effect Analysis ◽  
System Sensitivity ◽  
Full Band ◽  
Digital Spectrometer ◽  
The Ideal

THz Atmospheric Limb Sounder (TALIS) is a microwave radiometer designed by the National Space Science Center of the Chinese Academy of Sciences (NSSC, CAS) for measuring the vertical distribution of temperature and chemical constituents in the middle and upper atmosphere. The digital spectrometer is an important part of TALIS’ back end, which mainly realizes the function of spectral analysis. The radix 16 real-time complex fast Fourier transform (FFT) algorithm used in the digital spectrometer was obtained by improving and combining the parallel processing and complex processing of the FFT algorithm. In this study, the digital spectrometer parameter selection is systematically presented, and the effect of the digital spectrometer FFT algorithm on the TALIS system sensitivity is analyzed based on the TALIS system simulation model we established in the previous stage of this research. The results show that the actual full-band sensitivity obtained after using the FFT algorithm is consistent with the ideal full-band sensitivity of TALIS for different integration time, spectral resolutions, and quantization bits. However, the results of the comparison of the actual sub-band sensitivity after using the FFT algorithm with the ideal sub-band sensitivity show that the deterioration of the sub-band sensitivity will be caused by the FFT algorithm. The mean value of the deterioration ratio was found to be approximately 18%, and the maximum value of the deterioration ratio was approximately 33%.

scholarly journals Non-destructive Dielectric Measurements and Calibration for Thin Materials Using Waveguide-Coaxial Adaptors

2014 ◽  
Vol 14 (1) ◽  
pp. 16-24 ◽  
Author(s):  
K. Y. You ◽  
Z. Abbas ◽  
M. F. A. Malek ◽  
E. M. Cheng
Keyword(s):  
Calibration Method ◽  
Calibration Procedure ◽  
Reflection Coefficients ◽  
Dielectric Measurements ◽  
Finite Samples ◽  
Open Standard ◽  
Rectangular Waveguides ◽  
Standard Values ◽  
Calibration Techniques ◽  
Non Destructive

Abstract This paper focuses on the calibration of apertures for rectangular waveguides using open-short-load (OSL) standards and transmission-line (TL) approaches. The reflection coefficients that were measured using both calibration techniques were compared with the coefficients acquired using the thru-reflect-line (TRL) method. In this study, analogous relationships between the results of OSL calibration and TL calibration were identified. In the OSL calibration method, the theoretical, open-standard values are calculated from quasi-static integral models. The proposed TL calibration procedure is a simple, rapid, broadband approach, and its results were validated by using the OSL calibration method and by comparing the results with the calculated integral admittance. The quasi-static integral models were used to convert the measured reflection coefficients to relative permittivities for the infinite samples and the thin, finite samples

Spin-polarization effects in Cherenkov radiation from electrons

2020 ◽  
Vol 98 (7) ◽  
pp. 660-663
Author(s):  
A.A. Peshkov
Keyword(s):  
Spin Polarization ◽  
Cherenkov Radiation ◽  
Stokes Parameters ◽  
Electron Spin Polarization ◽  
Polarized Electrons ◽  
Small Component ◽  
Polarization Effects ◽  
Spin Polarized ◽  
Linearly Polarized ◽  
Spin Polarization Effects

A quantum electrodynamical theory of Cherenkov radiation emitted by spin-polarized electrons moving in an isotropic medium is developed within the density matrix framework. Special attention is paid to the polarization properties of the emitted photons described by means of Stokes parameters. It is demonstrated that, although the Cherenkov radiation is primarily linearly polarized in the plane containing the direction of observation and the path of the electrons, the photons may have a small component of circular polarization of the order of 3 × 10−6 for electron kinetic energy of 500 keV due to the initial electron spin polarization, whose existence can be confirmed by sensitive measurements in the future.

scholarly journals Correlation Functions of CMB Anisotropy and Polarization

1999 ◽  
Vol 183 ◽  
pp. 104-104
Author(s):  
Kin-Wang Ng
Keyword(s):  
Correlation Function ◽  
Stokes Parameters ◽  
Temperature Anisotropy ◽  
Microwave Background ◽  
Signal To Noise ◽  
Polarization Experiment ◽  
Promising Tool ◽  
Cmb Polarization ◽  
Full Analysis ◽  
Cross Correlations

While the temperature anisotropy of the cosmic microwave background is proved to be a promising tool for probing the early Universe, the CMB polarization is another important clue for extracting more cosmic information. We give a full analysis of the auto- and cross-correlations between the CMB Stokes parameters. In particular, we derive the windowing function for an antenna with Gaussian response in polarization experiment, and construct correlation function estimators corrected for instrumental noise. They are applied to calculate the signal to noise ratios for future MAP and Planck anisotropy and polarization measurements.

THE CALIBRATION OF AN ARRAY OF ACCELEROMETERS

2011 ◽  
Vol 35 (2) ◽  
pp. 251-267 ◽  
Author(s):  
Dany Dubé ◽  
Philippe Cardou
Keyword(s):  
Angular Velocity ◽  
Rigid Body ◽  
Least Squares ◽  
Calibration Method ◽  
Calibration Procedure ◽  
Rigid Bodies ◽  
New Method ◽  
Scale Factors ◽  
Array Calibration ◽  
The One

An accelerometer-array calibration method is proposed in this paper by which we estimate not only the accelerometer offsets and scale factors, but also their sensitive directions and positions on a rigid body. These latter parameters are computed from the classical equations that describe the kinematics of rigid bodies, and by measuring the accelerometer-array displacements using a magnetic sensor. Unlike calibration schemes that were reported before, the one proposed here guarantees that the estimated accelerometer-array parameters are globally optimum in the least-squares sense. The calibration procedure is tested on OCTA, a rigid body equipped with six biaxial accelerometers. It is demonstrated that the new method significantly reduces the errors when computing the angular velocity of a rigid body from the accelerometer measurements.

Convenient Calibration Procedure for Structured Light Projection System

2013 ◽  
Vol 662 ◽  
pp. 777-780
Author(s):  
Wen Guo Li ◽  
Shao Jun Duan
Keyword(s):  
Relative Position ◽  
Structured Light ◽  
Calibration Method ◽  
Calibration Procedure ◽  
Shape Measurement ◽  
Projection System ◽  
System Calibration ◽  
3D Shape ◽  
3D Shape Measurement ◽  
Projector Calibration

We present a convenient calibration method for structured light projection system. The proposed clibration approach can realize 3D shape measurement without projector calibration, without system calibration, without precise linear z stage to be used, the relative position between camera and projector can be arbitrary, and the only involved device is a plane board. Experiment results validated that the accuracy of the proposed approach.

Sign in / Sign up

Export Citation Format

Share Document