Reflective Toraldo pupil for high-resolution millimeter-wave astronomy

A novel, to the best of our knowledge, beam-shaping reflective surface for high-resolution millimeter/ submillimeter-wave astronomy instruments is presented. The reflector design is based on Toraldo’s superresolution principle and implemented with annulated binary-phase coronae structure inspired by the achromatic magnetic mirror approach. A thin, less than half a free-space wavelength, reflective Toraldo pupil device operated in the W-band has been fabricated using mesh-filter technology developed at Cardiff University. The device has been characterized on a quasi-optical test bench and demonstrated expected reduction of the beam width upon reflection at oblique incidence, while featuring a sidelobe level lower than −10 dB. The proposed reflective Toraldo pupil structure can be easily scaled for upper millimeter and infrared frequency bands as well as designed to transform a Gaussian beam into a flat-top beam with extremely low sidelobe level

Development of large-diameter flat mesh-lenses for millimetre wave instrumentation

We present novel optics solutions based on metal mesh flat lenses which can be used to mimic a refracting lens. This approach removes the bulk of the dielectric materials (polyethylene or silicon) required for fast optical refracting systems. Additional attractive property of these lenses is that they filter out unwanted higher frequency radiation, they are easy to anti-reflection coat and they are extremely light. Measurements from 300mm diameter prototypes of both a Fresnel-type graded-index lens and a phase-delay type mesh-lens are presented

Passive intermodulation in printed transmission lines

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