Research And Analysis Of Rectangular Horn Antenna's Measurement And Noises

In this dissertation, using new noise mechanisms and new calculation methods, the rectangular horn antenna which has found the 3K background radiation is analyzed and researched, it can improve the accuracy of antenna measurements. The dissertation is divided into the following sections to study:(1) The dissertation introduces the elementary knowledge of the horn antenna, and the aperture field and the radiation field of horn antenna are analyzed by theoretical methods, and on the basis of the radiation field, the radiation characteristics of horn antenna are analyzed, such as antenna pattern, directivity, antenna efficiency, antenna gain, and antenna input impedance.(2) The dissertation analyses the noise sources of impacting the antenna temperature, such as noise sources within the system and external noise sources. And it also describes the two-calibration method of the radiometer standard method, which consists of step by step method calibration and aperture-calibration method, and the two methods of calibration are analyzed.(3) The composition and the works of the modules in the rectangular horn antenna are analyzed and researched, besides, with new noise mechanisms and new calculation methods to calculate the internal noises and external noises which impact the antenna temperature, and using the aperture-calibration method to calculate the total noise temperature.(4) Using the electromagnetic simulation software MATLAB to simulate the radiation characteristics of the rectangular horn antenna, to obtain the radiation characteristics of the antenna.In the dissertation, using the aperture-calibration method to calculate the rectangular horn antenna's noise temperature, the aperture-calibration method considers radiometer receiver and antenna and feeder as a whole, determines both high and low temperature points, can calculate the antenna temperature calibration equation directly, so it can reduce the noise analysis of each modules, reduce the unnecessary calculation and the errors which caused in the calculated process, to improve the measurement accuracy.