Abstract: Docked devices communicate wirelessly and in close proximity using multiple transmitters of Extremely High-Frequency (EHF) signals of 30-300 GHz. The devices may not be precisely aligned when docked. Tolerance of misalignment is improved by adding barriers such as solid metal blocks or rows of metal-filled vias that have a spacing of less than one-quarter the EHF wavelength. The barriers reflect EHF radiation and prevent EHF radiation from penetrating the barrier. Barriers placed between adjacent transmitters and receivers block stray electromagnetic radiation from causing cross-talk. The barriers can be placed closer to the transmitters than to the receivers to allow for a wider area for reception, permitting a wider misalignment. EHF reflecting features such as ground planes spaced a quarter-wavelength apart may be added to an end of a substrate near a connecting edge to act as a barrier and reflect electromagnetic radiation back toward an intended receiver.