Design of compact printed multi band mimo antennas for wireless communication systems

Abstract

In present days, wireless communication technology has catapulted newlinethe demand for high-speed data rate communication and handheld devices to newlinesupport multiple wireless services in commercial sectors. In this field of newlinewireless communication, the emergence of Multiple-Input-Multiple-Output newline(MIMO) technology, make a tremendous growth that employs multiple newlineantennas for transmission and reception of signals and linearly increase the newlinechannel capacity if the multi-path channels are not correlated, according to newlineShannon s theorem (Bliss 2005).In the past few years, wireless communication systems targeting towards the fourth generation and the focus on multi-band MIMO antenna newlinedesign get increased attention among wireless terminal designers. These newlinemulti-band MIMO antennas can solve the problem of backward compatibility newlinewith existing 2G and 3G wireless services along with 4G and WLAN newlinestandards. In multi-band MIMO antenna design, the inter-element spacing newlineplays a key role which is the main cause to produce constructive or newlinedestructive interferences. It is noteworthy that the phase difference between newlinethe transmitting waves of each co-located radiators is the principal source of newlinesuch interferences. In this context, when the number of elements increases, newlinethe coupling mechanism also increases and results in a high coupling newlinecoefficient which in turn lowers the communication data rate. Since the newlineantenna elements are strongly coupled together in a compact antenna design, newlineit is not an easy task to keep up the isolation characteristics between them. newline newline