A low-cost rotationally symmetric probe for terahertz near-field scanning

This paper presents a novel THz near-field probe based on a pyramidal-shaped TE
₁₀
mode rectangular open ended waveguide (OEWG) incorporated with a complementary source. The complementary source, placed at the tip of the OEWG, is realized on a single-layered substrate using standard printed-circuit and plated-through-hole technologies. The pyramidal-shaped probe is designed not only for its mechanical strength but also for achieving symmetric and equal E- and H-plane radiation patterns. The designed probe redistributes the energy of the TE
₁₀
mode over the radiating aperture to excite both rotationally symmetric TE
₁₁
and TM
₁₁
modes. Simulation and measurement results with good agreement are presented at 0.3 THz. The designed probe is a good candidate for spherical near-field measurement in THz frequency range.