In this paper, a new design of a broadband planar printed antenna based on the academic log periodic antenna is presented. The antenna consists of a series of printed dipoles, distributed on both faces of the substrate. Some configurations are explored, with a different number of printed dipoles. These are designed, simulated, fabricated, and measured. The calculated and measured return losses and radiation patterns are presented. The utility of the proposed antenna associated with its frequency bandwidth is better than 80%. The measured absolute gain is 6.5 dBi, and the front‐to‐back ratio is around 8 dB. The presented antenna should find wide applications in wireless communication systems and phased arrays. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 402–405, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21363

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The half-moon antenna has been proposed for wideband applications. The half-moon antenna with variable tilt angles has been shown to have variable frequency band characteristics. The bandwidth of the proposed antenna is obtained from 1.5 GHz to more than 5 GHz. In this frequency band, omnidirectional radiation patterns have been observed. The radiation patterns are almost immune to the tilt angles. A description of how the proposed antenna gets the wideband operation in this half-moon structure is provided, and required equations are also derived. All the simulation and measured data agree very well with confirming the validity of our theory and the used models. The concept can be simply adapted to design for other antennas operating at different frequency bands. 2. W.L. Langston and D.R. Jackson, Impedance, axial-ratio, and receivepower bandwidths of microstrip antennas, ABSTRACT: A directive broadband printed Yagi-like antenna design is presented. We have focused on the 2.45 GHz WLAN band, at which some designs have been carried out. For the design and the modelling processes, we made use of FDTD based in-house developed algorithms. Some selected prototypes have then been fabricated onto a low-cost printed circuit board dielectric substrate and tested successfully. Bandwidths higher than 10% and moderate to high (Ͼ7 dBi) gains can be obtained this way. ABSTRACT: The concept of very simple planar high-pass filters using microstrip with short-circuited edge has been extended to filters with passbands beginning in the K and K a bands. Two examples of such filters have been designed using electromagnetic simulator and fabricated on 0.5-mm thick alumina substrate and on 0.254-mm thick low permittivity organic substrate. Theoretical characteristics have been compared with the experimental data demonstrating practical utility of the proposed filter concept at frequencies attaining the millimeter-wave range.

which are improvements of 12.8 and 11 dB, respectively, over the conventional DPA. Figure 10 shows the measured drain efficiency versus ACLR characteristics of various conditions for a 1-carrier WCDMA signal. The power tracking DPA at an ACLR of Ϫ45 dBc can produce a Pout of 43.4 dBm with the drain efficiency of 31%, which is the efficiency assuming that the efficiency of drain bias supply circuit is 100%. CONCLUSIONSWe have proposed the three-way DPA with the adaptive bias supply using the power tracking method for improving linearity of the DPA while preserving high efficiency. To achieve good linearity of the DPA without extra linearization techniques, the drain bias voltage of the carrier amplifier and the gate and drain bias voltages of the peaking amplifiers are controlled adaptively according to input power levels. To verify this method, a three-way DPA was implemented using 30-W Si LDMOSFETs and tested using two-tone and 1-carrier WCDMA signals at 2.14 GHz. We have observed the significant IM3 cancellation for a two-tone test with 1-MHz tone spacing. We have also achieved superior ACLR performance for a 1-carrier WCDMA signal over a wide operating power range. At an ACLR of Ϫ45 dBc, the power tracking DPA can produce a Pout of 43.4 dBm with a drain efficiency of 31%. The measured results confirm that the linearity of the DPA is improved with the adaptive bias control of the gate and drain bias voltages of the DPA without extra linearization techniques, while obtaining high efficiency. A robust modeling and design approach for dynamically loaded and digitally linearized Doherty amplifiers, IEEE Trans Microwave Theory Tech 53 (2005), 2875-2883. 4. K.J. Cho, J.H. Kim, and S.P. Stapleton, A highly efficient Doherty feedforward linear power amplifier for W-CDMA base-Stations applications, IEEE Trans Microwave Theory Tech 53 (2005), 292-300. 5. Y. Yang, J. Yi, Y.Y. Woo, and B. Kim, A fully N-way Doherty amplifier with optimized linearity, IEEE Trans Microwave Theory Tech 51 (2003), 986 -993. 6. J. Kim, J. Cha, I. Kim, and B. Kim, Optimum operation of asymmetrical-cells-based linear Doherty power amplifiers-uneven power drive and power matching, IEEE Trans Microwave Theory Tech 53 (2005), 1802-1809. 7. H.-I Pan and G.A. Rincon-Mora, Asynchronous nonlinear power-tracking supply for power efficient linear ABSTRACT: A low cost directive uniplanar broadband printed Quasi-Yagi antenna design is presented. As a particular realization, some prototypes have been designed to operate in the 2.45 GHz band. They have been then modeled, fabricated onto standard printed circuit dielectric substrate and tested successfully. For the design and the modeling processes, we have make use of FDTD based in-house developed algorithms. The obtained bandwidth is, for all the considered cases, better than 15%. The main radiation characteristics are 2-5.5 dBi gain, depending on the number of director elements, and better than 25 dB front-to-back ratio.Overall antenna size was, in any case lesser than 1 ϫ 0.5 .

Abstract:A novel integrated optical source capable of emitting faint pulses with different polarization states and with different intensity levels at 100 MHz has been developed. The source relies on a single laser diode followed by four semiconductor optical amplifiers and thin film polarizers, connected through a fiber network. The use of a single laser ensures high level of indistinguishability in time and spectrum of the pulses for the four different polarizations and three different levels of intensity. The applicability of the source is demonstrated in the lab through a free space quantum key distribution experiment which makes use of the decoy state BB84 protocol. We achieved a lower bound secure key rate of the order of 3.64 Mbps and a quantum bit error ratio as low as 1.14 × 10 −2 while the lower bound secure key rate became 187 bps for an equivalent attenuation of 35 dB. To our knowledge, this is the fastest polarization encoded QKD system which has been reported so far. The performance, reduced size, low power consumption and the fact that the components used can be space qualified make the source particularly suitable for secure satellite communication.