Underwater visible light communication can be used to measure the quality of the transmission medium not only for communication. We used three different LEDs for communication and measured the amplitude of the detected signal. The measured value can be compared to a reference point and the transmission medium caused attenuation can be calculated. There is a connection between the attenuation and the pollution of the water. We will show that the type of the water can be identify if only the attenuation is measured.

The efficient design of electrically small antennas (ESA) has recently evolved to an outstandingly active area of research. This paper aims to present an improved performance electrically small on-chip antenna design, for the 920 MHz UHF-RFID frequency. Performance improvement is based on creating a slow-wave structure with threedimensional spiral meandering and dielectric loading of the complete antenna structure. A single layer spiral on-chip antenna simulation is presented first, based on a commercially available product, then an improved single layer spiral antenna and finally an alternative 3D multi-layer spiral on-chip antenna is investigated. The proposed alternative on-chip antenna structure fills a 2.5 x 2.5 x 1.3 mm 3 volume and has significantly improved radiation performance compared to the single layer solution.

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During the analytical design process of wideband impedance matching major problems may arise, that might lead to non-realizable matching networks, preventing the successful impedance matching. In this paper two practical design rules and a simplified equation is presented, supporting the design of physically realizable impedance matching networks. The design rules and calculation technique introduced by this paper is summarized, and validated by microwave circuit simulation examples.

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