DARPA is soliciting innovative research approaches imaging radar architecture that use an electronic sub-reflector to produce a more readily available, cost effective sensor solution that does not require
platform or target motion.
The goal of the Advanced Scanning Technology for Imaging Radars (ASTIR) program is to demonstrate a new imaging radar architecture using an electronic sub-reflector to produce a more readily available, cost effective sensor solution that does not require platform or target motion as in SAR or ISAR. The ASTIR concept will minimize system complexity by using a compound antenna with an electronic sub-reflector and a single transmit/receive chain. The sub-reflector would work in concert with a large primary aperture that would define the angular resolution of the radar.
Possible approaches to achieve imaging/beam-steering with the sub-reflector include (but are not limited to):
- Replacing an electro-mechanically displaced mirror, as currently used in some imaging radars, with a planar electronically reflecting surface to do beam steering.
- Using phase-shifters on the sub-reflector to steer a small spot across the main reflector. This small spot is sequentially scanned across the entire main reflector, and synthetic aperture radar (SAR) processing techniques are used to create a fully focused three dimensional image.
- Digitally modulating each element on the sub-reflector with an orthogonal phase code. After the signal is received, digital code-division processing is applied to create digital channels, and then SAR techniques are used to create a fully focused three dimensional image.
Awards:
- :
- Base Contract Value: $499,237,
- Option Value if Exercised: $1,993,658
- : 125961123
- : 5340 Airport Boulevard; Boulder, Colorado 80301
- :$881,786 (Base),
- $2,940,600 (Option 1), and
- $2,923,077 (Option 2)
: Northrop Grumman Systems Corporation
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| Reflectarray Antennas |
Background/Related
- DARPA launches ASTIR program to develop advanced imaging radar using electronic sub-reflectors
- Proposers Day
www.darpa.mil/WorkArea/DownloadAsset.aspx?id=2147488147 DARPA Aug 18, 2014 - Advanced Scanning Technology for Imaging Radars - racette_estf2011 - A Novel Reflector/Reflectarray Antenna.pdf
References
- Berry, D.; Malech, R.; Kennedy, W., "The reflectarray antenna," Antennas and Propagation, IEEE Transactions on , vol.11, no.6, pp.645,651, Nov 1963
doi: 10.1109/TAP.1963.1138112
Abstract: A class of antennas that utilizes arrays of elementary antennas as reflecting surfaces has been investigated. An antenna of this type is here called a Reflectarray. It has been found that the Reflectarray combines much of the simplicity of the reflector-type antenna with the performance versatility of the array type. The reflecting surfaces employed in these antennas are characterized by a surface impedance that can be synthesized to produce a variety of radiation patterns. The equations of the surface impedance as a function of the desired reflected phase front is derived for the lossless case and methods of realizing this surface impedance are presented. Experimental results of a waveguide array type Reflectarray are given including pencil beam, broad beam and scanning modes. Data on the effects of specific phase errors are presented.
keywords: {Antenna arrays;Reflector antennas;Waveguide arrays;Antenna arrays;Antenna radiation patterns;Apertures;Feeds;Optical arrays;Optical surface waves;Optical waveguides;Reflector antennas;Shape control;Surface impedance},
URL: http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=1138112&isnumber=25407. - Gallacher, T.F.; Robertson, D.A.; Smith, G.M., "The Photo-Injected
Fresnel Zone Plate Antenna: Optoelectronic Beam Steering at mm-Wave
Frequencies," Antennas and Propagation, IEEE Transactions on , vol.61, no.4, pp.1688,1696, April 2013
doi: 10.1109/TAP.2012.2237004
Abstract: We present an overview of the photo-injected Fresnel zone plate antenna (piFZPA) method for non-mechanical optoelectronic beam steering. The piFZPA method enables rapid beam steering, over moderate field-of-views, at both mm-wave and submm-wave frequencies, that is suitable for a wide range of imaging and non-imaging applications. This paper develops a theoretical framework that details the design of piFZPAs and provides an understanding to, and optimization of, the piFZPA performance. As an example device, we present preliminary experimental scanning data on a transmission-type piFZPA, operating at 94 GHz, that relies on commercially available visible display technologies for plasma generation and reconfiguration. The experimental data is shown to agree well with numerical simulations and validates the theoretical framework.
keywords: {millimetre wave antennas;numerical analysis;fíeld-of-views;frequency 94 GHz;mm-wave frequencies;nonimaging applications;nonmechanical optoelectronic beam steering;numerical simulations;optoelectronic beam steering;photo-injected Fresnel zone plate antenna;photo-injected fresnel zone plate antenna;piFZPA method;piFZPA performance;plasma generation;submm-wave frequencies;Adaptive optics;Gain;Optical attenuators;Optical imaging;Plasma density;Substrates;Beam forming;Fresnel zone plate;beam steering;optically controlled antenna;optoelectronic;photo-injected Fresnel zone plate},
URL: http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6399528&isnumber=6493417
. - Tamminen, A, T. F. Gallacher, et al, “Developments of reflectarray and its element characterization at millimeter wavelengths”, Proceeding of SPIE Vol 9078, “Passive and Active Millimieter-Wave Imaging XVII”, May 2014.
- Arttu Luukanen ; Juha Ala-Laurinaho ; David Gomes Martins ; Janne Häkli ; Päivi Koivisto, et al. "Rapid beamsteering reflectarrays for mm-wave and submm-wave imaging radars", Proc. SPIE 8022, Passive Millimeter-Wave Imaging Technology XIV, 80220M (May 25, 2011); doi:10.1117/12.887068; http://dx.doi.org/10.1117/12.887068
I did some work on a cassegrain antenna with a phased array on the sub reflector for Raytheon in 1969. The project was called TPN-19. It is interesting how this concept is now coming to reality after so many years.
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