Določanje kapacitivnosti standardnega kondenzatorja po metodi štirih priključkov

Štibernik, Klemen (author), Ponikvar, Dušan (mentor)

V zaključni nalogi je predstavljena merilna metoda, s katero lahko izračunamo kapacitivnost štiriportnih etalonov kapacitivnosti v odvisnosti od frekvence in sicer do frekvenc višjih od 10 MHz. Namen merilne metode je pridobiti etalonske vrednosti kapacitivnosti etalonov pri frekvencah, kjer neposredna meritev z kapacitivnostnim mostom ni mogoča. Točne vrednosti kapacitivnosti etalonov so potrebne za kalibracijo novejših LCR merilnikov, ki so sposobni meriti kapacitivnost pri frekvencah, večjih od 1 MHz. V zaključni nalogi bom uporabil merilno metodo, ki je bila razvita v Nacionalnem metrološkem inštitutu v Turčiji, kjer so izpopolnili delo, ki je bilo opravljeno v Hewlett-Packard raziskovalni ustanovi na Japonskem. Pri merilnem postopku bom uporabil poenostavljen model vezja kondenzatorja in predpostavil teoretični model frekvenčne odvisnosti kapacitivnosti kondenzatorja. Vrednosti elementov poenostavljenega vezja, ki nastopajo v modelu, bom določil z meritvami. Pri meritvah kapacitivnostih elementov modela bo uporabljen kapacitivnostni most. Vrednost induktivnih elementov bom določil z meritvijo sipalnih parametrov, ki so kompleksna razmerja vpadnih in odbitih valov harmonskega napetostnega valovanja, merjena z vektorskim analizatorjem vezja. Rezultate bom primerjal z vrednostmi, ki so objavljene v literaturi in z etalonskimi vrednostmi kondenzatorjev, ki so bile pridobljene na kalibraciji v LNE (Laboratoire national de métrologie et d'essais) inštitutu. Merilno negotovost bom ocenil po splošnih vodilih, ki veljajo v metrologiji.

• Language: Slovenian
• Keywords: kapacitivnost, impedanca, etalon kapacitivnosti
• Work type: Final paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: FMF - Faculty of Mathematics and Physics
• Year: 2019
• PID: 20.500.12556/RUL-111381
• COBISS.SI-ID: 3374180
• Publication date in RUL: 29.09.2019

Secondary language

• Language: English
• Title: Determination of capacitance of a standard capacitor by the four-terminal method

Abstract

In this final assignment, I will present a measuring method with which we can calculate the capacitance of four port capacitance standards with relation to frequencies beyond 10 MHz. The purpose of this measuring method is to obtain accurate capacitance values for capacitance standards at frequencies where traditional measurement with capacitance bridge is not possible. Accurate values for the capacitance of standards are needed for calibration of newer LCR meters which are capable of measuring the capacitance at frequencies greater than 1 MHz. This measuring procedure was developed at the National Metrology Institute in Turkey where researchers had built on the work that was done in Hewlett-Packard research facility in Japan. Using this measuring procedure, I will use a simplified model of a standard capacitor and using this model I will calculate the frequency dependence of capacitance. Values of parameters which are represented in the simplified model will be determined through measurements. Capacitive parameters will be measured with a capacitance bridge. Inductive parameters will be calculated from scattering parameter measurements, which are complex ratios of the incident and reflected harmonic voltage waves, obtained by a vector network analyzer. I will compare the results with the values reported in the literature and with the standard values of the capacitors obtained at the LNE (Laboratoire national de métrologie et d'essais) calibration. I will evaluate the measurement uncertainty according to the general guidelines that apply in metrology.

• Keywords: Capacitance, Impedance, Capacitance standard