Construction and Measurement of a 31.3–45 GHz Optimized Spline-profile Horn with Corrugations

摘要

A corrugated spline-profile horn has been designed to meet thestringent specifications and constraints of a receiver for Band 1 (31.3–45 GHz)of the Atacama Large Millimeter Array (ALMA). Given the physicalrestrictions of the receiver, the horn will be located behind a focusing lensplaced 191 mm over its aperture. After this first focusing stage, the horn musthave a reflection coefficient less than -20 dB and the cross-polarization notexceeding the -30 dB level in the entire frequency range. The side-lobesshould be less than -25 dB at all frequencies and its half power beamwidthmust be approximately 24 at 31.3 GHz and 16 at 45 GHz. The horn has beenconstructed using the split-block technique and characterized in a near-fieldscanner setup. The results show an excellent performance complying with allthe requirements.