Fig. 2. Geometry and fundamental TEM modes of the four-wire waveguide (FWWG).
a Schematic of the FWWG architecture. The FWWG consists of four identical copper wires (radius r = 127 µm) equally separated by an air gap (g = 300 µm), arranged into a square geometry. b, c Simulated electric field intensity distributions of the fundamental TEM modes evaluated at 0.5 THz, TEMx (b), and TEMy (c), which can be efficiently excited by x-polarized and y-polarized THz beams, respectively. The arrows in the 2D distributions indicate the local electric field polarization directions.