The goal of this Master's thesis was the design and manufacturing of a high-frequency power meter, which is useful for various antenna measurements and laboratory experiments. Special emphasis was placed on the ability to measure antenna radiation pattern diagrams up to the Ku, K and Ka frequency bands as well as capturing and interfacing the measured data for further processing.
The introduction analyzes different techniques of measuring signal power at high frequencies. A brief description of the most common implementations of high-frequency power meters is included. The measurement principles and advantages as well as limitations of different techniques are presented.
The main part of the thesis involves design and manufacturing of the power meter itself. The radio-frequency sensing head is based on the ADL6010 diode-detector chip as the power sensor. The latter is installed on a printed-circuit board feeding the input signal using a coplanar waveguide. The most important parameters of the input coaxial connector, coplanar waveguide, ADL6010 and additional components are carefully characterized.
The interface unit is designed to capture and display the measured signal from two radio-frequency sensing heads. The LPC2138/01 32bit ARM microcontroller enables digital processing (filtering) of the measured signals and correcting the response of ADL6010 chip, thus achieving a higher measurement accuracy at low signal levels. The program code is written in assembler and, among other things, it allows selective detection of high-frequency signals based on amplitude modulation, which enables more accurate measurements of antennas in the presence of interferences in an uncontrolled environment.
The final part of the thesis presents the characteristics of designed power meter. Sample measurements of radiation patterns and antenna directivities in the X and Ku frequency bands are included.
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