Antenna design challenges and solutions for compact MIMO terminals

The design of antennas for compact multiple-input multiple-output (MIMO) terminals is a challenging feat, due to the space constraint and the physical structure of the terminal. The space constraint forces the antennas to be closely spaced, which degrades MIMO performance due to high signal correlation and low antenna efficiency. Moreover, the terminals are equipped with ground planes which further complicate the implementation of antennas for good MIMO performance. This paper elaborates on the two aforementioned challenges in MIMO antenna design and surveys recent techniques that are developed to address these challenges.