Analysis on pattern multiplexing gain of integrated slot antennas loaded with t-shaped conductor for maximizing channel capacity

Abstract

To increase channel capacity with limited frequency resources in wireless communication, multiple-input multiple-output (MIMO) technology has been proposed. However, the distance among element antennas should be larger than 0.5 wavelengths to increase the channel capacity by applying the conventional MIMO system. So the MIMO system cannot be applied to a system having small antenna space. Meanwhile, it was indicated that we can achieve the channel capacity with an arbitrary small antenna as much as six times compared to an element antenna by utilizing polarization and pattern multiplexing gain. This gain can be obtained by using three magnetic dipoles and three electric dipoles positioned orthogonally. After it was shown, there have been many researches on the design of practical small antenna which have radiation patterns resembling with the three magnetic dipoles and the three electric dipoles. More recently, it was found that we can obtain with a small antenna higher channel capacity than six times of an element antenna to get polarization and pattern multiplexing gain if some radiation resistance is approved. It means that we can increase the channel capacity with a given space for the antenna if the system allows some radiation efficiency. The results of these studies can be applicable to an actual system since the radiation efficiency of the antenna is not an important factor in the wireless communication. However, there have been few researches on the design of the practical multiple element antenna(MEA) which possesses small space and obtain the high channel capacity by utilizing pattern multiplexing gain. In this paper, we proposed MEA which can get higher channel capacity than ideal 6-port polarimetric antenna and occupy only a sphere with radius R $\le$ 0:25 $\lambda$. First, we proposed a design concept of practical MEA by analyzing the characteristics of spherical vector waves (SVW) which are basis functions of radiation pattern. We proposed a co...