Applied Electromagnetism in Mobile Communications: antenna design, biological effects and diversity system performance

The use of the electromagnetic fields at different frequencies and intensities, like mobile phones, wireless communications and wearable communications, received a lot of attention from many researchers from different fields. The development of mobile phones and the miniaturization of portable electronic devices also stimulated many related research studies, like biological effects of electromagnetic fields, design of proper antennas for mobile terminals of satellite broadband communication systems, on-body communications. The purpose of the first part of this thesis is to provide an understanding of the non thermal biological effects of electromagnetic fields. The objective was to evaluate the intensity of the electric field within different geometrical biological cells. The cell models have been simulated using CST MWS, and they have been exposed to a linearly polarized electromagnetic plane wave. Evaluations of the mutual interaction and transmembrane potential have been performed. On the second part of this thesis the attention has been focused on a different application which regards the design of a rectangular dielectric resonator antenna operating in Ku frequency band. This new antenna is proposed to be used as a radiating element of a TX phased array of active integrated antennas (AIAs). Since in a transmitting AIA, the radiator has to provide a proper load for the power amplifier, two new techniques have been implemented in order to optimize the system performance at the fundamental frequency and first harmonics as well. The first technique is based on the use of the two additional slots. These two slots have been introduced parallel to the main coupling slot. The second harmonic tuning technique is based on a proper choice of the rectangular dielectric resonator dimensions, namely the shape factor. By using these techniques it is possible to control the input impedance at the second and third harmonic without influencing the impedance behaviour at the fundamental frequency. The antenna has been ...