High Efficiency Wideband Refractive Optics for ALMA Band-1 (35-52 GHz)
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We present the design, implementation, and characterization of the optics of ALMA Band 1, the lowest frequency band in the most advanced radio astronomical telescope. Band 1 covers the broad frequency range from 35 to 50 GHz, with the goal of minor degradation up to 52 GHz. This is, up to now, the largest fractional bandwidth of all ALMA bands. Since the optics is the first subsystem of any receiver, low noise figure and maximum aperture efficiency are fundamental for best sensitivity. However, a conjunction of several factors (small cryostat apertures, mechanical constraints, and cost limitations) makes extremely challenging to achieve these goals. To overcome these problems, the optics presented here includes two innovative solutions, a compact optimized-profile corrugated horn and a modified Fresnel lens. The horn profile was optimized for optimum performance and easy fabrication by a single-piece manufacturing process in a lathe. In this way, manufacturability is eased when compared with traditional fabrication methods. To minimize the noise contribution of the optics, a one-step zoned lens was designed. Its parameters were carefully optimized to maximize the frequency coverage and reduce losses. The optical assembly reported here fully complies with ALMA specifications.
KeywordsHorn antenna Dielectric lens antenna Optics
- 1.A. Wootten, and A. Thompson, ”The Atacama Large Millimeter/Submillimeter Array,” Proceedings of the IEEE, vol.97, 1463 (2009).Google Scholar
- 2.H. Rudolf, M. Carter, and A. Baryshev, ”The ALMA Front End Optics—System Aspects and European Measurement Results”, IEEE Transactions on Antennas and propagation, vol. 55, (2007).Google Scholar
- 3.James W. Lamb, ”Low-Noise, High-Efficiency Optics Design for ALMA Receivers”, IEEE Transactions on antennas and propagation, vol. 51, N°.8, (2003).Google Scholar
- 4.J. Di Francesco et al.,”The science cases for building a Band 1 receiver suite for ALMA”, arXiv:1310.1604v3, (2013).
- 5.T. Huang et al., ”Development of Band-1 receiver cartridge for Atacama Large Millimeter/submillimeter Array (ALMA),” in Proc. SPIE 9153, Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy VII, p. 14. (2014).Google Scholar
- 6.μWave Wizardtm, Mician GmbH, software description. Available: http://www.mician.com/.
- 7.R. Gonzalo, J. Teniente, and C. del Río, ”Improved Radiation Pattern Performance of Gaussian Profiled Horn Antennas”, IEEE Transactions on antennas and propagation, Vol. 50, N°. 11, (2002).Google Scholar
- 8.J. Graeme L, ”Analysis and Design of TE11-to-HE11 Corrugated Cylindrical Waveguide Mode Converters,” Microwave Theory and Techniques, IEEE Transactions, vol. 29, NO. 10, pp. 1059, 1066 (1981).Google Scholar
- 9.C. Granet and Graeme L. James, ”Design of corrugated horns: a primer,” Antennas and Propagation Magazine, IEEE, vol. 47, N°. 2, pp. 76-84 (2005).Google Scholar
- 10.P.J.B. Clarricoats and P.K. Saha, ”Propagation and radiation behaviour of corrugated feeds. Part 1: Corrugated-waveguide fe bed,” Proceedings of the Institution of Electrical Engineers, vol. 118, no. 9, pp. 1167-1176, 1971.Google Scholar
- 11.High Frequency Structure Simulator, Ansys Academic Research, release 15.0.2.Google Scholar
- 12.N. Reyes, et al., ”Design of the optical system for ALMA Band 1,” in Proceedings of SPIE Vol. 9145, p. 91451W (2014).Google Scholar
- 13.A. Gonzalez, et al., ”Alternative optics design for the ALMA Band 1 receiver (35–52 GHz),” in European Conference on Antennas and Propagation (EuCAP), pp. 1-4 (2015).Google Scholar
- 14.M. Carter, et al., ”ALMA Front-end Optics,” ALMA, Design report FEND-40.02.00.00-035-B-REP, (2007).Google Scholar
- 15.M. Tejada, ”Fatigue and creep behavior of ALMA Band-1 lens,” Millimeter Wave Lab – U. Chile, Santiago, Chile, Mech. Rep., (2015).Google Scholar
- 16.J. L. Volakis (editor), ”Antenna Engineering Handbook”, Chapter 18, 4th Edition, Mc Graw-Hill, (2007).Google Scholar
- 17.T. Morita and S. B. Cohn, ”Microwave lens matching by simulated quarter-wave transformers”, IRE Transactions on Antennas and Propagation, vol. 4, no. 1, pp. 33-39, 1956.Google Scholar
- 18.MIG WASP-NET, software description. Available: http://www.mig-germany.com/.