Unleashing multiple antenna systems in compact terminal devices

Abstract

ABSTRACT:The effective use of multiple antenna systems in compact terminal devices is plagued by the problems of mutual coupling and spatial correlation. Consequently, increasing the number of antennas per unit volume results in rapidly diminishing returns after an upper limit is reached. We review recent advances on this topic of closely coupled antennas, including several existing techniques that may be used to push the boundary further, such that closely spaced antennas can still give good performance. A new approach of decoupling closely spaced antennas is also introduced.

High isolation and compact MIMO antenna system with defected shorting wall

“…However, the size of the EBG structure is too large for the low frequencies, which is not applicable in the compact devices. Other techniques such as neutralization technique [6], defected ground structure (DGS) [7], and coupling elements [8], may have larger size or long distance between the elements, which are not applicable for limited packages or need special fabrication techniques. Zhang [9] proposed a two-planar inverted F antenna (PIFA) antenna system with high isolation for wireless local area network (WLAN).…”

Performance improvement of closely spaced antennas incorporating a compensating network

“…A coupling neutralization technique using a suspended metal strip linking two antennas has been shown to improve port isolation in the 2 GHz UMTS band [4]. Placing a load-terminated parasitic antenna in the midpoint of two close active antennas can achieve similar results of reduced coupling [5]. Yet another concept is to consider the chassis as the main radiator and excite orthogonal mode currents thereon [6].…”