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A passive wireless temperature sensor with identification capabilities based on a phase modulation scheme is discussed in this paper. The approach presented utilizes a pulse backscatter technique based on slow wave (metamaterial) transmission lines. The focus of the work are the material engineering for the temperature-sensitive element and the integration of this element into a passive phase modulation circuit and the entire sensor tag. The approach makes use of temperature-sensitive bariumstrontium-titanate thick film capacitances. The discussed principle has been experimentally verified with a prototype.

For the realization of tunable matching networks, different approaches based on functional materials or micromechanical devices with varying performances has been presented in the past. The dynamic control of these devices requires the measurement of the transmitted power. This paper evaluates different methods for adequate power measurement within the context of mobile communication devices in the frequency range of 500 MHz to 5 GHz. The circuits are analyzed and compared concerning their insertion loss, integrability, size and multiband-capability.

In this paper we present the impact of acoustic resonances excited by electrostriction in BST thin-films on the Q-factor of a varactor in the GHz range. By changing the process-parameter substrate to target distance while sputtering the thin-films, we observe a change in the acoustic resonance frequencies. To characterize the material properties which determine the acoustic resonance frequencies a model based on a 1D acoustic transmission line is used. The extracted material properties results in a proportional dependency to the changed process parameter. For verification of the acoustic transmission line model 3D simulations have been performed which show good agreement to the line model for lower resonance frequencies, where the difference at higher frequencies becomes significant due to additional higher order modes.