Multiport Pixel Antenna Optimization Using $N$-Port Characteristic Mode Analysis

An approach for pixel antenna optimization is proposed in this paper. This approach uses $N$-port characteristic mode analysis (CMA) in optimization to find as many independent and orthogonal modes of pixel structures as possible within a limited space. After as many orthogonal resonant modes as possible are found, some new feeding port searching methods are expected to be used to excite these modes in order to make MIMO antennas. This approach does not need the design of additional feeding structures, which take up additional space, therefore it is straightforward, concise, and efficient. An example was used to validate the approach and demonstrate its effectiveness.

I. Introduction

In wireless communication, MIMO technology is widely used as it can maximize the channel capacity with limited transmitting power and spectrum resources [1]. Antenna design is challenging because the space left for antenna design in mobile terminals is often limited. Placing multiple antennas in a limited space results in smaller distances between the antennas, making the coupling between the antennas significant. The decoupling between antennas attracts a lot of attention and generates a lot of work [2]–[4].