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In this paper, a new empirical model for indoor propagation prediction is presented. The inspiration for our model is to enhance existing empirical models for indoor propagation prediction by incorporating additional phenomena suggested by electromagnetic techniques such as the uniform theory of diffraction (UTD), but still retain the straightforwardness of the empirical approach. The advantage is that computation time for indoor propagation prediction is low without greatly compromising prediction accuracy. Comparisons of our predicted results to measurements indicate that improvements in accuracy over conventional empirical models are achieved. Index Terms - Indoor radio communication, propagation.

A capacitively loaded planar inverted-F antenna (PIFA) is proposed and studied. It is found that the capacitive load reduces the resonance length of the PIFA from [Lambda]/4 to less than [Lambda]/8. A design with a bandwidth of 178 MHz centered at 1.8 GHz is provided to demonstrate that compact antennas for mobile telephone handsets can be constructed using this approach. The finite-difference time-domain (FDTD) method is used in the study and experimental verification is also provided. Index Terms - FDTD methods, mobile antennas.

In this paper, a technique for enhancing the reconstruction quality of diffraction tomography for microwave imaging is presented. The technique invokes the WKB approximation in conjunction with utilizing measurement data at more than one frequency to overcome some of the limitations of diffraction tomography. The resulting formulation has a mathematical interpretation which leads to some interesting insights into the limitations of diffraction tomography. Numerical implementation of the technique is also described and actual simulation results using this implementation for a variety of two-dimensional (2-D) objects are provided. These show that indeed significant improvements over conventional diffraction tomography are possible with our enhanced technique.

Planar inverted F antennas (PIFA) have been proposed as possible candidates for mobile telephone handsets. In this letter, we describe the design of a compact PIFA suitable for operation at 900 MHz. In addition, we provide modifications to this design that allow it to operate in dual-frequency bands at 900 and 1800 MHz. Finite-difference time-domain (FDTD) and experimental results are provided. Index Terms - Antennas, mobile communication.