Experimental Demonstration of Reflectarrays Acting as Conic Section Subreflectors in a Dual Reflector System

This paper experimentally demonstrates the use of a microstrip reflectarray as a low-profile planar substitute to a conic section subreflector (hyperboloidal type) in a symmetric dual reflector system at Ku-band. At first, a brief discussion on the simulation and measurement techniques utilized in t...

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Bibliographic Details
Published in:IEEE transactions on antennas and propagation 2013-11, Vol.61 (11), p.5475-5484
Main Authors: Rajagopalan, Harish, Shenheng Xu, Rahmat-Samii, Yahya
Format: Article
Language:English
Subjects:
Antenna measurements
Antenna radiation patterns
Antennas
Apertures
Applied sciences
Back projection
Beams (radiation)
compensation
conic
Conics
defocusing
Equations
Exact sciences and technology
Feeds
Flats
Horns
hyperboloidal
Measurement techniques
microstrip
near-field measurements
Phase measurement
Radiocommunications
reflector
Reflector antennas
Reflectors
Simulation
subreflectarray
Subreflectors
Telecommunications
Telecommunications and information theory
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Summary:This paper experimentally demonstrates the use of a microstrip reflectarray as a low-profile planar substitute to a conic section subreflector (hyperboloidal type) in a symmetric dual reflector system at Ku-band. At first, a brief discussion on the simulation and measurement techniques utilized in the paper is provided. A nominal dual reflector Cassegrain system is synthesized through simulations where a feed horn is used to illuminate the hyperboloidal subreflector. Next, a flat metallic subreflector is placed at the subreflector location. This is a critical task as it shows the importance of phase compensation. Due to the flat subreflector, the feed is defocused from the image of the focus and creates phase aberration, leading to beam bifurcation, pattern degradation, and performance deterioration of the dual reflector system. A planar microstrip patch-type subreflectarray is then designed to mimic a hyperboloidal subreflector. Ray tracing is applied to the subreflector-feed system to calculate the phase needed to compensate for the axial defocusing of the feed. A prototype subreflectarray based on the ray-optics approach is fabricated. Radiation pattern measurements and back-projection holographic diagnostics demonstrate that the subreflectarray acts as a hyperboloidal subreflector and restores the antenna performance with a well-defined main beam and low side lobes.
ISSN:0018-926X
1558-2221
DOI:10.1109/TAP.2013.2277716