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
This paper presents the design of a printed step-type monopole antenna for biological tissue analysis and medical imaging applications in the microwave frequency range. The design starts from a very simple and widely known rectangular monopole antenna, and different modifications to the antenna geometry are made in order to increase the bandwidth. The antenna dimensions are optimized by means of a parametric analysis of each dimension using a 3-D electromagnetic simulator based on the finite element method. The optimized antenna, with final dimensions of 40 × 36 mm2, is manufactured onto a low-cost FR4 (fiber glass epoxy) substrate. The characteristics of the antenna have been measured inside an anechoic chamber, obtaining an omnidirectional radiation pattern and a working frequency range between 2.7 GHz and 11.4 GHz, which covers the UWB frequencies and enables the use of the antenna in medical imaging applications. Finally, the behaviour of four of these antennas located around a realistic breast model, made with biocompatible materials, has been analysed with the electromagnetic simulator, obtaining good results and demonstrating the usefulness of the designed antenna in the proposed application.
This work presents a study on the implementation and manufacturing of low-cost microwave electronic circuits, made with additive manufacturing techniques using fused deposition modeling (FDM) technology. First, the manufacturing process of substrates with different filaments, using various options offered by additive techniques in the manufacture of 3D printing parts, is described. The implemented substrates are structurally analyzed by ultrasound techniques to verify the correct metallization and fabrication of the substrate, and the characterization of the electrical properties in the microwave frequency range of each filament is performed. Finally, standard and novel microwave filters in microstrip and stripline technology are implemented, making use of the possibilities offered by additive techniques in the manufacturing process. The designed devices were manufactured and measured with good results, which demonstrates the possibility of using low-cost 3D printers in the design process of planar microwave circuits.
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 .
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