MIMO Mobile Handset Antenna Merging Characteristic Modes for Increased Bandwidth

The behavior of a mobile handset chassis-mode antenna with a metal bezel is analyzed in this paper by utilizing the theory of characteristic modes (TCM). Two eigenmodes, one from the chassis (0.5λ-dipole mode) and the other one from the bezel (1λ-perimeter mode), are merged by a monopole exciter to broaden the antenna bandwidth below 1 GHz. A new eigenmode from the bezel (1.5λ-perimeter mode) is also exploited to achieve multiple-input multiple-output (MIMO) performance. The characteristics of the antenna are verified with an experimental prototype and measurements. The measured input reflection bandwidths from the two ports are 263 MHz (742-1005 MHz) and 93 MHz (863-956 MHz), respectively. The port isolation is more than 7.4 dB across the whole band of interest. Finally, the monopole exciter, which excites two eigenmodes in the lowfrequency band, is modified to provide more resonances in the upper frequency band, providing coverage in the range of 1715- 2060 MHz and 2280-2710 MHz.