Abstract-A novel antenna configuration for quad-band operation is presented. The quad-band antenna has a directional radiation pattern in four frequency bands, i.e., B1 (800-900 MHz), B2 (1.7-2.5 GHz), B3 (3.3-3.6 GHz), and B4 (5.1-5.9 GHz), covering all spectrums for existing wireless applications, such as GSM, PCS, WCDMA, WiFi, and WiMax. The operating frequency of the quad-band antenna can be adjusted by the use of a MEMS switch, making it suitable for cognitive radio applications. First a switchable quad-band antenna element is introduced. Then a two-element antenna array is developed to increase the antenna gain for base station applications featuring a gain value of about 9-11 dBi over all four frequency bands.Index Terms-Base station antenna, cognitive radio, quad-band antenna, switchable antenna.

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Abstract-The tri-band mobile antenna system for broadband multimedia services in the Ka/K-band and a simultaneous direct broadcast service in the Ku-band has been developed. The radiating part of the antenna consists of a shaped dual reflector system and a tri-band feed of circular polarization. The low-profile offset main reflector has an aperture size of 60 cm 20 cm; therefore, a fan beam is formed which is sharp in azimuth and wide in elevation. The feed system contains a protruding dielectric rod for Ka/K-band and 2 2 active phased array. The latter provides the beam for Ku-band along with four fast electrical beams for stable satellite tracking. The new tracking algorithm based on a fusion technique involving various sensors and fast electrical beams has also been introduced. The antenna system was mounted on a large ship and a test car, and successfully operated via Koreasat-3.Index Terms-Dual reflector, mobile antenna system, satellite tracking, tri-band feed.

Abstract:Microwave image reconstruction is typically based on a regularized least-square minimization of either the complex-valued field difference between recorded and modeled data or the logarithmic transformation of these field differences. Prior work has shown anecdotally that the latter outperforms the former in limited surveys of simulated and experimental phantom results. In this paper, we provide a theoretical explanation of these empirical findings by developing closed form solutions for the field and the inverted electromagnetic property parameters in one dimension which reveal the dependency of the estimated permittivity and conductivity on the absolute (unwrapped) phase of the measured signal at the receivers relative to the source transmission. The analysis predicts the poor performance of complex-valued field minimization as target size and/or frequency and electromagnetic contrast increase. Such poor performance is avoided by logarithmic transformation and preservation of absolute measured signal phase. Two-dimensional experiments based on both synthetic and clinical data are used to confirm these findings. Robustness of the logarithmic transformation to variation in the initial guess of the reconstructed target properties is also shown. The results are generalizable to three dimensions and indicate that the minimization form with logarithmic transformation offers image reconstruction performance characteristics that are much more desirable for medial microwave imaging applications relative to minimizing differences in complex-valued field quantities. 1998-2000 (1982). 2. J. C. Bolomey, L. Jofre, and G. Peronnet, "On the possible use of microwave-active imaging for remote thermal sensing," IEEE Trans. Microwave Theory Tech. 31, 777-781 (1983 ed. 24. Q. Lin, J. F. Vesecky, and H. A. Zebker, "New approaches in interferometric SAR data processing," IEEE Trans.Geosci. Remote Sens. 30, 560-567 (1992). 25. R. Gens and J. L. V. Genderen, "Review article SAR interferometry -issues, techniques, applications," Int. J.Remote Sensing 17, 1803-1835 (1996). 26. G. E. P. Box and D. R. Cox, "An analysis of transformation," J. Royal Stat. Soc. Serie B 26, 211-252 (1964 496-507 (1999).

This study is a computational study on focused microwave thermotherapy for knee pathological treatment using the time reversal (TR) principle in musculoskeletal disorders. The authors presented a modified TR algorithm with amplitude compensation for an accurate beam focusing of the knee tumour location in a lossy medium. Furthermore, they proposed a new approach called the truncated threshold method, which could be used to apply an effective beam focusing on a tumour location in the knee while the unwanted hot spots are controlled in the normal tissue region. Compared to the other existing methods, this new approach has the advantages of being implemented simply in the unwanted hot spot control and having a similar performance to the beam focusing on the target location. The application of the proposed algorithm and the new hot spot control method to knee pathological tissue achieved acceptable electromagnetic (EM) and thermal results. The anatomical based two‐dimensional (2D) knee model for the simulation analysis was implemented using a segmentation result of the Korean human body model obtained from magnetic resonance imaging. 2D finite‐difference time‐domain electromagnetic and thermal solvers were developed and applied to conduct the 915 MHz focused microwave thermotherapy for knee pathological treatment.