10 research outputs found
Design of Rectangular Patch Antenna on the Hilbert Fractal-shaped High Impedance Surface
No full text202-209The high Impedance Technique has emerged as a modern approach for high-gain microstrip antennas. A high impedance
surface minimizes surface waves and provides increased gain. Instead of, a typical mushroom to design High Impedance
Surface (HIS), fractal geometry can be used. Hilbert curve-based Fractal geometry minimizes physical length and keeps
electrical length the same. In this work, three iterations of Hilbert curve-shaped HIS geometry are studied with emphasis on
HIS application. Fractal facilitates multi-frequency operation from GSM 1800 MHz to 6 GHz Wireless applications. The
antennas have a peak gain of 5.3 dbi. The simulation is conducted in HFSS, and the analysis is performed using reports like
reflection coefficients, radiation patterns, and gain plot
Design and Analysis of Fractal-Shaped High-Impedance Surface Unit Cell Characteristics
No full textFractal geometries consistently provide solutions to several electromagnetic design problems. In this paper, fractal geometries such as Hilbert and Moore curves are used to design efficient High-Impedance Surfaces. Modern communication devices have many sensors that are needed to communicate wirelessly. The critical component of wireless communications is antennas. Planar microstrip patch antennas are popular due to their low profile, compactness, and good radiation characteristics. The structural disadvantages of microstrip antennas are that they have surface waves that propagate over the ground plane. High-Impedance Surface (HIS) planes are a prominent solution to minimize and eliminate surface waves. The HIS structures behave as active LC filters that suppress surface waves at their resonance frequency. The resonance frequency of the structure is obtained by its LC equivalent or by analyzing the reflection phase characteristics. This work presents conventional HIS structures similar to mushroom HIS and fractal HIS such as Hilbert curve and Moore curve HIS. The HIS reflection phase characteristics are obtained by applying periodic boundary conditions with plane wave illumination. The results were obtained in terms of the reflection phase angle. The conventional mushroom structures show narrow band characteristics at given dimensions of 10 mm × 10 mm and 20 mm × 20 mm. These structures are helpful in the replacement of PEC ground planes for patch antennas under sub-6 GHz. The Hilbert and Moore fractals are also designed and have a multiband response that can be useful for L, S, and C band applications. Another design challenge of HIS is protrusions, which make design difficult. The work also presents the effect of having vias and the absence of vias on reflection phase characteristics. The response shows the least and no significant effect of vias under the x-band operation
Recommended from our members
Correction for Slik et al., Phylogenetic classification of the world’s tropical forests
No full textCorrection for "Phylogenetic classification of the world's tropical forests, " by J. W. Ferry Slik, Janet Franklin, Víctor Arroyo- Rodríguez, Richard Field, Salomon Aguilar, Nikolay Aguirre, Jorge Ahumada, Shin-Ichiro Aiba, Luciana F. Alves, Anitha K, Andres Avella, Francisco Mora, Gerardo A. Aymard C., Selene B?ez, Patricia Balvanera, Meredith L. Bastian, Jean-François Bastin, Peter J. Bellingham, Eduardo van den Berg, Polyanna da Conceição Bispo, Pascal Boeckx, Katrin Boehning-Gaese, Frans Bongers, Brad Boyle, Fabian Brambach, Francis Q. Brearley, Sandra Brown, Shauna-Lee Chai, Robin L. Chazdon, Shengbin Chen, Phourin Chhang, George Chuyong, Corneille Ewango, Indiana M. Coronado, Jurgi Crist?bal-Azkarate, Heike Culmsee, Kipiro Damas, H. S. Dattaraja, Priya Davidar, Saara J. DeWalt, Hazimah Din, Donald R. Drake, Alvaro Duque, Giselda Durigan, Karl Eichhorn, Eduardo Schmidt Eler, Tsutomu Enoki, Andreas Ensslin, Adand? Belarmain Fandohan, Nina Farwig, Kenneth J. Feeley, Markus Fischer, Olle Forshed, Queila Souza Garcia, Satish Chandra Garkoti, Thomas W. Gillespie, Jean- Francois Gillet, Christelle Gonmadje, Iñigo Granzow-de la Cerda, Daniel M. Griffith, James Grogan, Khalid Rehman Hakeem, David J. Harris, Rhett D. Harrison, Andy Hector, Andreas Hemp, J?rgen Homeier, M. Shah Hussain, Guillermo Ibarra-Manríquez, I. Faridah Hanum, Nobuo Imai, Patrick A. Jansen, Carlos Alfredo Joly, Shijo Joseph, Kuswata Kartawinata, Elizabeth Kearsley, Daniel L. Kelly, Michael Kessler, Timothy J. Killeen, Robert M. Kooyman, Yves Laumonier, Susan G. Laurance, William F. Laurance, Michael J. Lawes, Susan G. Letcher, Jeremy Lindsell, Jon Lovett, Jose Lozada, Xinghui Lu, Anne Mette Lykke, Khairil Bin Mahmud, Ni Putu Diana Mahayani, Asyraf Mansor, Andrew R. Marshall, Emanuel H. Martin, Darley Calderado Leal Matos, Jorge A.Meave, Felipe P. L. Melo, Zhofre Huberto Aguirre Mendoza, Faizah Metali, Vincent P. Medjibe, Jean Paul Metzger, Thiago Metzker, D. Mohandass, Miguel A. Munguía-Rosas, Rodrigo Muñoz, Eddy Nurtjahy, Eddie Lenza de Oliveira, Onrizal, Pia Parolin, Marc Parren, N. Parthasarathy, Ekananda Paudel, Rolando Perez, Eduardo A. P?rez-García, Ulf Pommer, Lourens Poorter, Lan Qi, Maria Teresa F. Piedade, Jos? Roberto Rodrigues Pinto, Axel Dalberg Poulsen, John R. Poulsen, Jennifer S. Powers, Rama Chandra Prasad, Jean-Philippe Puyravaud, Orlando Rangel, Jan Reitsma, Diogo S. B. Rocha, Samir Rolim, Francesco Rovero, Andes Rozak, Kalle Ruokolainen, Ervan Rutishauser, Gemma Rutten, Mohd. NizamMohd. Said, Felipe Z. Saiter, Philippe Saner, Braulio Santos, João Roberto dos Santos, Swapan Kumar Sarker, Christine B. Schmitt, Jochen Schoengart, Mark Schulze, Douglas Sheil, Plinio Sist, Alexandre F. Souza, Wilson Roberto Spironello, Tereza Sposito, Robert Steinmetz, Tariq Stevart, Marcio Seiji Suganuma, Rahayu Sukri, Aisha Sultana, Raman Sukumar, Terry Sunderland, Supriyadi, H. S. Suresh, Eizi Suzuki, Marcelo Tabarelli, Jianwei Tang, Ed V. J. Tanner, Natalia Targhetta, Ida Theilade, Duncan Thomas, Jonathan Timberlake, M?rcio de Morisson Valeriano, Johan van Valkenburg, Tran Van Do, Hoang Van Sam, John H. Vandermeer, Hans Verbeeck, Ole Reidar Vetaas, Victor Adekunle, Simone A. Vieira, Campbell O.Webb, Edward L. Webb, Timothy Whitfeld, Serge Wich, John Williams, Susan Wiser, FlorianWittmann, Xiaobo Yang, C. Yves Adou Yao, Sandra L. Yap, Rakan A. Zahawi, Rahmad Zakaria, and Runguo Zang, which was first published February 5, 2018; 10.1073/pnas.1714977115 (Proc Natl Acad Sci USA 115:1837-1842). The authors note that, due to a printer's error, an author name published incorrectly. The author name Lan Qi should instead appear as Lan Qie. The online version has been corrected
The general as statesman : exploring the professional need for commanders to support viable political outcomes in peace and stability operations as typified by the UK military approach
Get PDFThe problem of theatre level politico-military arrangements during peace and stability operations is important because the intervening actors, working in complex and often ambiguous circumstances, need to calibrate the application of military and political means as a coherent interdependent whole. This is necessary in order to build peace, secure viable political outcomes and hence strategic successes; however it is not easy in practice. This thesis examines the hypothesis that, beyond their security-related tasks, military commanders should provide direct support to civilian interlocutors in order to facilitate and sustain the local political process. This requires military co-operation with other relevant actors, responsiveness to political direction and the specific shaping of military operations to impact decisively on political outcomes.
This work establishes that Western and United Nations doctrinal guidance extols political primacy and civil-military cooperation but does not fully explain the central importance of the political process, nor does it capture the potential peace building role of the military component. Analysis of practice in Kosovo, Iraq and Afghanistan, suggests that military commanders retain a uniquely influential position and have generally used their military means to positively influence political progress and help coordinate multi-dimensional plans. On occasion, to secure momentum and fill a void, commanders have quietly assumed a political function. Doctrine now needs to be refreshed to reflect practice. It should explain the military role in supporting the political process, elaborate the politico-military relationship as the inner core of a comprehensive approach to peace building and provide candid guidance on the difficulties to be expected where politico-military and coordination arrangements are incoherent. Moreover further work is needed on the wider application of this doctrine by the United Nations and the preparation of civilian leaders for politico-military relationships
Design of Rectangular Patch Antenna on the Hilbert Fractal-shaped High Impedance Surface
Get PDFThe high Impedance Technique has emerged as a modern approach for high-gain microstrip antennas. A high impedance surface minimizes surface waves and provides increased gain. Instead of, a typical mushroom to design High Impedance Surface (HIS), fractal geometry can be used. Hilbert curve-based Fractal geometry minimizes physical length and keeps electrical length the same. In this work, three iterations of Hilbert curve-shaped HIS geometry are studied with emphasis on HIS application. Fractal facilitates multi-frequency operation from GSM 1800 MHz to 6 GHz Wireless applications. The antennas have a peak gain of 5.3 dbi. The simulation is conducted in HFSS, and the analysis is performed using reports like reflection coefficients, radiation patterns, and gain plot
