We present a design methodology for high-capacity line-of-sight communication arrays in the radiative near-field of each other. We optimize the equivalent aperture current distribution of highly directive antennas in order to obtain noise-limited independent data streams with maximal average signal to noise interference ratio over a range of link distances. The current distributions, equal for the transmit and receive arrays, are found to be defined by the Prolate Spheroidal Wave Function in amplitude and a quadratic phase focusing term. We show that these optimized arrays reach the same coupling levels as when using beamforming techniques without the need for phase control per element. We also demonstrate that this optimization allows the use of fixed beamforming weights rather than highly variable weights over link distance. Finally, we study a 2x2 array at 270 GHz with 6λ0 diameter elements where the desired aperture current distribution is synthesized using a leaky-wave lens antenna fed by a double-iris slot and a focusing hyperbolic lens. Appropriate modeling of the aperture current distributions results in good agreement between transfer matrix calculations and FW simulations.

This paper presents a comparative study of different Multiple Input Multiple Output (MIMO) array architectures to realize high-capacity Point-to-Point (PtP) wireless links for potential use in future 6G backhauling applications. This study focuses on the 220-320 GHz band, defined by the new IEEE 802.15.3d standard. Both phased array and focal plane array architectures are studied, considering the link to operate in the radiative near-field. The theoretically achievable capacities are presented based on the channel matrix estimated in the radiative near-field and the application of Shannon’s capacity formula. It is found that capacities well above Tbps rates can theoretically be realized, even without the use of interference cancellation techniques.