A Broadband W-Band Polarization Rotator With Very Low Cross Polarization

• Published in: IEEE microwave and wireless components letters 2011-03, Vol.21 (3), p.127-129
• Main Authors: Pisano, Giampaolo, Melhuish, Simon, Savini, Giorgio, Piccirillo, Lucio, Maffei, Bruno
• Format: Article
• Language: English
• Subjects: Applied sciences; Astronomical instruments; Broadband; Broadband communication; Circuit properties; Circular waveguides; Cosmic microwave background; Cross polarization; Devices; Electric, optical and optoelectronic circuits; Electronics; Exact sciences and technology; Loss measurement; Microwave circuits, microwave integrated circuits, microwave transmission lines, submillimeter wave circuits; Modulation and coding; Networks; Noise levels; Optical waveguides; Performance evaluation; Polarization; Rotation measurement; Transducers; Transmission line matrix methods; waveguide polarizers
• ISSN: 1531-1309; 2771-957X; 1558-1764; 2771-9588
• DOI: 10.1109/LMWC.2011.2104942

We present a 82-100 GHz circular waveguide polarization rotator based on a broadband rotating half-wave retarder. The device was designed for astrophysics experiments aimed to characterize the polarization of the cosmic microwave background radiation. The device is based on a Pancharatnam recipe used in optics and has a very low intrinsic cross polarization, very flat phase response across the band and very low losses. It can be used in astronomical experiments where very high performance is required but also as a variable polarization source for instrument calibrations. The design was manufactured and then tested using a millimeter-wave vector network analyzer. The average measured RL, IL and cross polarization across a 30% bandwidth were, respectively, -38 dB, -0.27 dB, and -36.5 dB.