Terahertz Corrugated Horns (1.25${\hbox{--}}$ 1.57 THz): Design, Gaussian Modeling, and Measurements

Corrugated horns are the feed of choice at millimeter and submillimeter wavelengths for quasi-optical systems in applications, which require high beam quality and low cross polarization over wide bandwidths, such as radio astronomy. However, this kind of feeds is difficult to manufacture at terahertz frequencies due to technological limits. Using the heritage established during Atacama Large Millimeter/Submillimeter Array band 10 (0.79-0.95 THz) production, some prototype corrugated horns for the 1.25-1.57 THz band have been designed and fabricated by direct machining. Two different kinds of corrugated horns with similar performance have been considered: long conical-profile corrugated horns and shorter profiled corrugated horns. A new modeling method has been proposed to obtain the quasi-optical parameters of the resulting horns and realize frequency independent quasi-optical designs. Patterns of the fabricated corrugated horns have been measured and results agree well with simulations. To the best of our knowledge, this is the first time corrugated horns have been successfully fabricated by direct machining for use up to 1.57 THz.