W-band prototype of platelet feed-horn array for CMB polarisation   measurements
  We present the design and performance of a 2x2 prototype array of corrugated feed-horns in W-band. The module is fabricated using a so-called "platelet" technique by milling Aluminum plates. This technique is suitable for low-cost and scalable high performance applications. Room temperature Return Loss measurements show a low (<-30 dB) reflection over a 30% bandwidth with a maximum matching of -42 dB at 100 GHz for all four antennas. Beam pattern measurements indicate good repeatability and a low (-25 dB) sidelobe and crosspolarisation levels. This work is particularly relevant for future Cosmic Microwave Background polarisation measurements, which require large microwave cryogenic detector arrays coupled to high performance corrugated feed horns. 
Francesco Del Torto, Marco Bersanelli, Francesco Cavaliere, Adriano De   Rosa, Ocleto D'Arcangelo, Cristian Franceschet, Mas...
astro-ph.IM astro-ph.CO