The generation of RF/microwave power is required not only in wireless communications, but also in applications such as jamming, imaging, RF heating, and miniature dc/dc converters. Each application has its own unique requirements for frequency, bandwidth, load, power, efficiency, linearity, and cost. RF power is generated by a wide variety of techniques, implementations, and active devices. Power amplifiers are incorporated into transmitters in a similarly wide variety of architectures, including linear, Kahn, envelope tracking, outphasing, and Doherty. Linearity can be improved through techniques such as feedback, feedforward, and predistortion.
The field penetration of electromagnetic hyperthermia applicators in 2.5-29 g l-1 saline (NaCl) solutions over a range of frequencies is investigated. Calculated field penetration based on the current-element method agrees well with measurement at frequencies above about 100 MHz, but at lower frequencies measured field penetration becomes progressively less than calculated as conductivity is reduced. Experimental results and finite-difference time-domain (FDTD) method modelling show that the electromagnetic field produces circulating currents. The effect of these circulating currents on the heating pattern of the applicators should be considered when planning hyperthermia treatment.
Abs~uct-An enhanced three-dimensional Finite-Difference Time-Domain (FDTD) technique is applied to the characterization of the fundamental and higher order modes of single and coupled image guide structures. The basic FDTD algorithm is modified to include multidimensional changes of permittivity and an irregular mesh is used for computational efficiency. In this paper FDTD calculations are compared with experimental and theoretical results found in the literature and good agreement is found.
Abstract-Microwave cooking, tempering, and pasteurizing of foods involves several complex and interacting physical phenomena. Although such processes are widely used, the interactions between the food product, packaging, and the microwave oven itself are particularly complicated, are not well understood, and applicable simulation tools are lacking. In this contribution we describe a combined finite difference time domain model for the electromagnetic and the heat transfer processes which include temperature dependence of the electrical and thermal properties of the food product. This model is validated by comparison to experiment.
In this contribution we present results for a combined electromagnetic and thermal model which calculates the three-dimensional time-temperature distributioln as a1function of electromagnetic energy dissipation. In this paper an enhanced version of the Finite-Difference Time-Domain (FDTD) method is used in conjunction with a heat transfer model specifitally for the thermal analysis of current sheet hyperthermia applicators. However, the general algorithm is applicable; to a wide range of industrial, scientific, medical and communication applications which involve high frequency electromagnetic waves.
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