Jari-Matti Hannula ON THE USE OF INTERMODULATION RESPONSE FOR CHARACTERIZING ANTENNAS

Author: Jari-Matti Hannula Title: On the Use of Intermodulation Response for Characterizing Antennas Date: May 20, 2015 Number of pages: 63 Unit: Department of Radio Science and Engineering Field of research: Radio Science and Engineering Supervisor: Assistant Professor Ville Viikari Advisor: M.Sc. (Tech.) Kimmo Rasilainen The intermodulation measurement technique enables the contactless measurement of transponder antennas by exploiting the inherent nonlinearity of the transponder to generate intermodulation products that can be measured. This intermodulation response can then be used to characterize the antenna. In this master’s thesis, this characterization technique is developed further. The theoretical intermodulation response for a harmonic transponder is derived, and this response is then used in measurements to characterize the transponder antenna. Limitations of the dynamic range of the measurement are discussed. The measurement can be performed using different arrangements of the measurement antennas. Three potential measurement geometries are discussed and compared: monostatic, bistatic, and multistatic. A measurement software is created for controlling the measurement. The derived theory is validated by experiments. The measured intermodulation response of a harmonic transponder is compared with the theoretical response. The measurement technique is then used to measure the gain of the transponder antenna using bistatic geometry. The impedance matching of the transponder is also measured. The results show good agreement between the derived theory and the measurements. Based on the results, it can be said that the technique is well-suited for characterizing harmonic transponders.