Overview of antenna problems and solutions for multi-Gb/s links

Fundamental limitations in link budgets for wireless indoor networks are considered for millimeter and THz frequencies. Single small antennas at those frequencies are a bottle neck due to the small absorption areas and the ensuing path loss. Although different for LOS links and links in diffuse surroundings, there are no theoretical limitations, if complexity is ignored. Complexity and power consumption may be reduced by using analog solutions where possible, and in the paper we focus on phase conjugation methods, specifically in retrodirective arrays. Considering power solutions only, mimicking optical networks, we call attention to an array of rectennas.