A W-Band Radiometer with the Offset Parabolic Antenna for Radiometric Measurements

Li Wu,Jian-Zhong Xu,Ze-Long Xiao,Shu-Sheng Peng

doi:10.1155/2016/4705072

Abstract

This paper deals with the development of a W-band noise-adding radiometer which combines the millimeter-wave (MMW) radiometric measurements with a high-resolution imager. The offset parabolic antenna is presented to achieve an accurate measurement and a high resolution. To reduce the cross-polarization level of the antenna, a multimode feed horn with a multistep structure is proposed to match the focal region fields of the reflector. It has advantages over the corrugated horns in lower mass and easier manufacturing. In addition, due to an unavoidable settling time for the noise-adding radiometer output signal passing through the low-pass filter, a theoretical criterion for the optimum duty cycle determination to reject extraneous contributions from the transient is proposed in this paper. The appropriate duty cycle threshold is 0.33 for the developed W-band radiometer. Also, a geometric correction method is presented to correct the obtained passive image suffering from a distortion for a better image interpretation. Preliminary experimental results are given to illustrate and verify the presented techniques.

Highlights

Due to the advantages of passive and convert operations and smog penetration, the MMW radiometer systems are often used for short to mid-range observations and detections in surveillance, reconnaissance, and target tracking on seekers or unmanned aerial vehicle platforms [1, 2]
Several groups of data samples chosen from the digitalized video amplifier output signal with different duty cycles were processed to retrieve the brightness temperature of the absorber
We have demonstrated a W-band noise-adding radiometer system with the large aperture offset parabolic antenna for radiometric measurements

Summary

Introduction

Due to the advantages of passive and convert operations and smog penetration, the MMW radiometer systems are often used for short to mid-range observations and detections in surveillance, reconnaissance, and target tracking on seekers or unmanned aerial vehicle platforms [1, 2]. A similar application is the improved surveillance and protection of sensitive infrastructures of nuclear power plants or mass events [3, 4]. It is employed for remote sensing of volcanic terrain at active lava domes in almost all weather conditions from ground-based survey points [5]. An accurate radiometric measurement of interested items is necessary to evaluate the performances of MMW imaging systems and to offer database for the contraband items detection, classification, and identification [8, 9].

Methods

Results

Conclusion