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ABSTRACT
Today, multimode antennas for MIMO (multiple-input multiple-output) systems have been used extensively to develop capacity or to improve the quality of WIFI. Due to the orthogonality of characteristic modes, the theory of characteristic modes used to achieve minimum interference between channels is common in this type of antennas.
In this paper, a four-port antenna with symmetric structure is presented on a circular patch to be able to produce four orthogonal patterns with extremely low correlation coefficients (less than 0.001) and high gain in the frequency range of 4.4–5.2 GHz and SWR <1.22, which is highly efficient in creating independent and simultaneous communication paths in MIMO systems. To create this orthogonality and decrease the correlation between channels, the characteristic modes method is used. Circular polarization can be obtained by changing feeding structure in this antenna.
Additional information
Notes on contributors
P. Mohamadi
Payman Mohammadi was born in Mashhad, Iran, in 1972. He received his BSc degree from Sharif University of Technology and MSc degree from Amir Kabir University of Technology, Tehran, Iran, respectively in 1994 and 1997, both in communication engineering. Since January 1994, he has been collaborating with ICT Research Institute on wave propagation analysis in different environments and RF circuit, and now, he is a PhD student at Islamic Azad University, Science and Research Branch. His main areas of interest in research are microstrip antenna, microwave passive, and active circuits. His research interests include the modal analysis of open structures, numerical methods, wave propagation, and MIMO antennas. E-mail: [email protected]
G. R. Dadashzadeh
Gholamreza Dadashzadeh was born in Urmia, Iran, in 1964. He received his BSc degree in communication engineering from Shiraz University, Shiraz, Iran, in 1992 and MSc and PhD degrees in communication engineering from Tarbiat Modarres University, Tehran, Iran, in 1996 and 2002, respectively. From 1998 to 2003, he has worked as the Head Researcher of the Smart Antenna for Mobile Communication Systems and the wireless local area network 802.11 project with the radio communications group of Iran Telecommunication Research Center (ITRC). From 2004 to 2008, he was the Dean of the Communications Technology Institute, ITRC. He is currently an Assistant Professor with the Department of Electrical Engineering, Shahed University, Tehran. He has published more than 200 papers in referred journals and international conferences in the area of antenna design and smart antennas. Dr Dadashzadeh is a member of the Institute of Electronics, Information, and Communication Engineers of Japan and the Iranian Association of Electrical and Electronics Engineers. He received the first degree of national researcher in 2007 from Iran’s Ministry of Information and Communications Technology.
M. Naser-Moghadasi
Mohammad Naser Moghadasi was born in Saveh, Iran, in 1959. He received his BSc degree in communication engineering in 1985 from the Leeds Metropolitan University (formerly Leeds Polytechnic), UK. Between 1985 and 1987, he worked as an RF design engineer for the Gigatech Company in Newcastle Upon Tyne, UK. From 1987 to 1989, he was awarded a full scholarship by the Leeds educational authority to pursue an MPhil in studying in CAD of microwave circuits. He received his PhD in 1993 from the University of Bradford, UK. He was offered then a 2-year post doc to pursue research on Microwave Cooking of Materials at the University of Nottingham, UK. From 1995, he joined Islamic Azad University, Science and Research Branch, Iran, where he currently is the head of postgraduate studies and also member of Central Commission for Scientific Literacy & Art Societies. His main areas of interest in research are microstrip antenna, microwave passive and active circuits, and radio frequency micro electromechanical systems (RF MEMS). He is a member of the Institution of Engineering and Technology, MIET and the Institute of Electronics, Information and Communication Engineers (IEICE). He has so far published over 130 papers in different journals and conferences. E-mail: [email protected]