Multi-band 2-port MIMO LTE antenna design for laptops using characteristic modes

Design of a 2-port Multiple Input - Multiple Output (MIMO) antenna system for monocoque laptops is the subject of this paper. The Theory of Characteristic Modes (TCM) is used to analyze a laptop chassis in the frequency range 704 MHz to 960 MHz. The results allow to find optimum placement of two exciters. Moreover, electric field expansion coefficients are calculated for both radiation modes of the antenna (i.e. the common mode and the differential mode) and per port. Therefore, a correspondence between radiation modes, as well as, per port excitation and characteristic modes is obtained. Finally, a multi-band 2-port MIMO antenna which exploits two different orthogonal superpositions of characteristic modes is designed and optimized.