A waveguide for receiving an incident electromagnetic wave (EMW) having an operating frequency Γ includes an array of spaced apart unit cells arranged along the waveguide. The unit cells are configured to resonantly couple to the incident EMW and radiate an EMW at the operating frequency propagating inside and along the waveguide. Each unit cell is configured to couple to the incident EMW with a first coupling efficiency and includes a dielectric body configured to couple to the incident EMW with a second coupling efficiency and one or more metal layers disposed on and partially covering the dielectric body. The second coupling efficiency is substantially smaller than the first coupling efficiency. A communication system includes the waveguide and a transceiver configured to emit an EMW having the operating frequency Γ.