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Beam Shaping and Feed Optimization for Terahertz Waves

English title Beam Shaping and Feed Optimization for Terahertz Waves
Applicant Kämpfer Niklaus
Number 119908
Funding scheme Project funding (Div. I-III)
Research institution Institut für angewandte Physik Universität Bern
Institution of higher education University of Berne - BE
Main discipline Other disciplines of Physics
Start/End 01.04.2008 - 31.03.2010
Approved amount 159'064.00
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Keywords (11)

THz; antennas; quasi-optics; millimeter and submillimeter waves; modal design; radio astronomy; Terahertz; antenna; quasi optics; remote sensing; microwave

Lay Summary (English)

Lead
Lay summary
Research in the millimeter and submillimeter wave region of the electromagnetic spectrum is of vital importance for a vast number of applications in radio astronomy, atmospheric remote sensing and other areas in physics. Most submillimeter wave instruments rely on free-space propagation in quasi-optical beam waveguides, and with the increasing sensitivity of the detectors the performance of these optics needs to be improved as well.

A key element for the design and the performance of quasi-optical systems is the feed, which couples the electromagnetic waves from free space into a waveguide or detector. In the first part of the proposal we plan to combine our Physical Optics and Gaussian Beam Mode models, which allow us to simulate the beam propagation through the optics, with our recently developed Mode Matching model, which allows the simulation of feed horns with arbitrary corrugations and profiles, in order to optimize both the optics and the feed together for an improved system performance. A first application for this will be the redesign of a feed horn for the ALMA pro ject, which cannot meet its specifications with the standard design that is currently used. Another immediate application of the combined feed/reflector design is the development of a beam condensing shroud for the ALMA calibration target.

For the THz limb sounder TELIS we are currently working on planar near-field antenna measurements of the telescope around 625 GHz. We plan to extend these tests and include also the cold optics and the superconducting integrated receiver in our setup. This is technically challenging since the superconducting local oscillator complicates accurate phase measurement, which requires a dedicated setup to cancel its phase noise. Depending on the results of these measurements we are planning to improve the design of the TELIS optics by shaping the first reflector after the lens antenna feed or by inserting dedicated field-stop apertures in order to reduce the higher order mode content of the beam.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

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Associated projects

Number Title Start Funding scheme
109509 Terahertz Optics 01.04.2006 Project funding (Div. I-III)
130517 Optical Design and Radiometric Tests for the Multibeam Limb Sounder STEAMR 01.04.2010 Project funding (Div. I-III)
124387 WADI: Atmospheric Water vapour from the ground to the mesopause: Detection and Interpretation 01.04.2009 Project funding (Div. I-III)

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