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Dichroic Filter for Separating W-Band and Ka-BandThe proposed Aerosol/Cloud/Ecosystems (ACEs) mission development would advance cloud profiling radar from that used in CloudSat by adding a 35-GHz (Ka-band) channel to the 94-GHz (W-band) channel used in CloudSat. In order to illuminate a single antenna, and use CloudSat-like quasi-optical transmission lines, a spatial diplexer is needed to add the Ka-band channel. A dichroic filter separates Ka-band from W-band by employing advances in electrical discharge machining (EDM) and mode-matching analysis techniques developed and validated for designing dichroics for the Deep Space Network (DSN), to develop a preliminary design that both met the requirements of frequency separation and mechanical strength. First, a mechanical prototype was built using an approximately 102-micron-diameter EDM process, and tolerances of the hole dimensions, wall thickness, radius, and dichroic filter thickness measured. The prototype validated the manufacturing needed to design a dichroic filter for a higher-frequency usage than previously used in the DSN. The initial design was based on a Ka-band design, but thicker walls are required for mechanical rigidity than one obtains by simply scaling the Ka-band dichroic filter. The resulting trade of hole dimensions for mechanical rigidity (wall thickness) required electrical redesign of the hole dimensions. Updates to existing codes in the linear solver decreased the analysis time using mode-matching, enabling the electrical design to be realized quickly. This work is applicable to missions and instruments that seek to extend W-band cloud profiling measurements to other frequencies. By demonstrating a dichroic filter that passes W-band, but reflects a lower frequency, this opens up the development of instruments that both compare to and enhance CloudSat.
Document ID
20120010450
Acquisition Source
Jet Propulsion Laboratory
Document Type
Other - NASA Tech Brief
External Source(s)
http://www.techbriefs.com/component/content/article/13864
Authors
Epp, Larry W. (California Inst. of Tech. Pasadena, CA, United States)
Durden, Stephen L. (California Inst. of Tech. Pasadena, CA, United States)
Jamnejad, Vahraz (California Inst. of Tech. Pasadena, CA, United States)
Long, Ezra M. (California Inst. of Tech. Pasadena, CA, United States)
Sosnowski, John B. (California Inst. of Tech. Pasadena, CA, United States)
Higuera, Raymond J. (California Inst. of Tech. Pasadena, CA, United States)
Chen, Jacqueline C. (California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
August 26, 2013
Publication Date
June 1, 2012
Publication Information
Publication: NASA Tech Briefs, June 2012
Subject Category
Man/System Technology And Life Support
Report/Patent Number
NPO-48174
Distribution Limits
Public
Copyright
Public Use Permitted.

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