【摘要】：相對介電常數(shù)和損耗角正切是微波介質材料的兩個重要性能參數(shù),近幾十年來,隨著微波技術的發(fā)展,微波電路以及天線正在向小型化方向發(fā)展,同時對微波介質材料的性能也提出了更高的要求,由此對微波介質材料電磁參數(shù)的精準測量也提出了更高的要求。本文針對電磁參數(shù)測量儀器存在價格昂貴、測量復雜、測量精度不高等問題,設計了一套寬帶電磁參數(shù)測量系統(tǒng)。文章首先介紹了比較成熟的電磁參數(shù)的測量方法,其次對本文所采用的測量方法與系統(tǒng)各個模塊的設計進行了詳細的介紹。本文主要工作如下：1、根據(jù)測量放置待測介質前后天線輸入阻抗的變化反演出介質的電磁參數(shù)的方法研發(fā)了一個寬帶電磁參數(shù)測量系統(tǒng),該系統(tǒng)可實現(xiàn)在1 GHz-3.5 GHz的頻率范圍內(nèi)對中、低介電常數(shù)介質材料和中、高損耗介質材料的相對介電常數(shù)和損耗角正切的測量；2、天線設計：由于系統(tǒng)利用的是近場微擾法而且測量帶寬較寬,故需要設計一款寬帶定向天線。通過對平面微帶天線的研究,并借助天線寬帶化技術,設計并制作了一款寬帶平面定向天線。該天線尺寸為90 mmx90 mm×1 mm,工作頻率范圍為1 GHz～4 GHz,極化方式為線極化。實測和仿真結果表面,該天線在測量系統(tǒng)頻段內(nèi)定向性良好,且實測最大增益可達到8dBi,能夠滿足寬帶電磁參數(shù)測量系統(tǒng)的要求；3、射頻電路的設計：設計了一款由表貼器件組成的寬頻帶射頻電路。并且為了提高測量系統(tǒng)的測量精度,減小電路帶來的誤差,針對射頻電路的特點專門設計了一套校準方法。在測量前首先使用所設計的校準方法對系統(tǒng)進行校準,然后對介質材料進行測量。實驗結果表明,所設計的校準方法能夠有效提高測量精度。4、基帶信號處理：采用STM32單片機采集射頻電路下變頻后的中頻信號,并通過對算法的編程處理,最終實現(xiàn)對介質材料的電磁參數(shù)的測量。
[Abstract]:Relative dielectric constant and loss angle tangent are two important performance parameters of microwave dielectric materials. In recent decades, with the development of microwave technology, microwave circuits and antennas are developing towards miniaturization. At the same time, higher requirements for the performance of microwave dielectric materials are put forward, and higher requirements for accurate measurement of electromagnetic parameters of microwave dielectric materials are put forward. Aiming at the problems of high price, complex measurement and low precision of electromagnetic parameter measuring instrument, a wideband electromagnetic parameter measuring system is designed in this paper. This paper first introduces the more mature measurement methods of electromagnetic parameters, and then introduces the measurement methods and the design of each module of the system in detail. The main work of this paper is as follows: 1. A wideband electromagnetic parameter measurement system is developed according to the method of measuring the variation of the input impedance of the antenna before and after placing the medium under test. The system can measure the relative dielectric constant and loss angle tangent of medium, low dielectric constant dielectric material and medium and high loss dielectric material in the frequency range of 1 GHz-3.5 GHz. 2. Antenna design: because the near field perturbation method is used in the system and the measurement bandwidth is wide, it is necessary to design a wideband directional antenna. Based on the research of planar microstrip antenna and wideband antenna technology, a broadband planar directional antenna is designed and fabricated. The antenna size is 90 mmx90 mm 脳 1 mm, operating frequency range is 1 GHz~4 GHz, polarization mode is linear polarization. The measured and simulated results show that the antenna has good orientation in the frequency band and the maximum gain can reach 8dBi. it can meet the requirements of wideband electromagnetic parameter measurement system. 3. Design of RF circuit: a wide band RF circuit is designed. In order to improve the measurement accuracy and reduce the error caused by the circuit, a calibration method is designed for the characteristics of RF circuits. The designed calibration method is used to calibrate the system before measurement, and then the dielectric material is measured. The experimental results show that the proposed calibration method can effectively improve the accuracy of measurement .4. baseband signal processing: STM32 single-chip microcomputer is used to collect if signals after down-conversion of RF circuits, and the algorithm is programmed to deal with them. Finally, the measurement of electromagnetic parameters of dielectric material is realized.
【學位授予單位】：南京信息工程大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：TM937
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本文編號：2227084