K-頻段輻射計量測及近場成像

Abstract

本論文係依據普朗克黑體輻射定律，使用K 頻段輻射計量測物體產生之雜訊功率。第一章介紹輻射計基本原理，第二章敘述輻射計之天線及接收機中頻及射頻模組量測結果，並計算天線解析度及接收機等效雜訊溫度。第三章第一節敘述接收機連接 20 dB 導波管天線為一輻射計，量測 50 歐姆負載、吸收體、鋁板及人手之雜訊功率，並計算物體之雜訊溫度。第二節則敘述接收機連接 85 cm 碟形天線為一輻射計，並安裝於二維平面掃描器，量測 1.38 公尺距離之近場物體 18 公分 X 18 公分所計算之雜訊功率，量測數值經 Visual Basic 程式控制及量測，並以MATLAB程式顯示物體之成像，量測物體包含吸收體、20 dB 增益天線之輻射低功率以及發熱之陶瓷電阻。

In this thesis, a K-band radiometer is developed to measure the noise power coming from an object based on Plank’s blackbody radiation law. The basic radiometer theory is briefly introduced in Chapter 1. The measured results of a 85 cm dish antenna, IF and RF stages of a receiver are presented in Chapter 2 to give the antenna spatial resolution and receiver noise temperature. In Sec. 3.1 of Chapter 3, the receiver is connected with a 20 dB horn antenna as a radiometer to measure the noise power of four different objects to calculate their noise temperatures. In Sec. 3.2.2, a radiometer is developed to connect the receiver and a 85 cm dish antenna. The radiometer is mounted on a 18 cm x 18 cm scanner as a near-field imaging system to measure the noise power from the test object at 1.385 m distance. The recorded result and image are controlled through a personal computer using Visual Basic and MATLAB programs. The near-field imaging several objects includes a low-power antenna, absorber and heated ceramic resistors.