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Frequency diverse arrays (FDA) are recently introduced. Not only the phased array and frequency scanning arrays, but also FDA provides electronic beam scanning ability. Moreover, electronic beam scanning is provided without the use of phase shifters or vector modulators. Nevertheless, reported studies on this concept do not provide practically implementable results. In this paper, fundamental expressions of the FDA operation and its typical implementation schemes are reviewed, and an ultimately useful scheme for implementing and FDA is introduced based on linear frequency modulated continuous waveform (LFMCW). The mathematical foundations of LFMCW FDA are developed and used to design a basic proof of concept structure. This structure is also implemented and the measurements related to the implementation are presented with discussions on the results.Index Terms-Frequency diverse arrays (FDA), linear frequency modulated continuous waveform (LFMCW), phased array structures.

Abstract-This paper proposes the configuration of a dualpolarized wide-band patch antenna system suitable for indoor mobile communication applications. This configuration consists of two patch antennas, which have different feed structures from classical patch antenna configuration. These antennas, which are separated by a thin absorber to have a good isolation, are fed independently to obtain dual polarization. The antenna structure is designed, simulated, manufactured and measured. The operation bandwidth spans 1900-2700 MHz covering Bluetooth, Wireless Local Area Networks (WLAN) and Universal Mobile Telecommunications System (UMTS) bands. The simulations show good agreement with the measurement results that the antennas have return losses higher than 15 dB, and the coupling between two antennas is below −20 dB within the operation band.

With a view to calculating depolarization and differential attenuation of microwaves by rain, with allowance for the variable shape and orientation of raindrops, the theory of P. C. Waterman is applied to the calculation of cross sections and depolarization ratios of spheroids, and drops of the shapes determined by H. R. Pruppacher and R. L. Pitter. Use of Waterman's extended boundary condition facilitates computation. The scattering characteristics of spheroids appear similar in nature to those of spheres, in the regimes considered. Marked singularities in the characteristics of backscattering depolarization appear at optical size 1.5. The Pruppacher and Pitter drops scatter similarly to equivalent oblate spheroids. Implications for weather radar measurements are briefly discussed.

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