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Title: SAR processing with stepped chirps and phased array antennas.

Abstract

Wideband radar signals are problematic for phased array antennas. Wideband radar signals can be generated from series or groups of narrow-band signals centered at different frequencies. An equivalent wideband LFM chirp can be assembled from lesser-bandwidth chirp segments in the data processing. The chirp segments can be transmitted as separate narrow-band pulses, each with their own steering phase operation. This overcomes the problematic dilemma of steering wideband chirps with phase shifters alone, that is, without true time-delay elements.

Authors:
Publication Date:
Research Org.:
Sandia National Laboratories
Sponsoring Org.:
USDOE
OSTI Identifier:
893561
Report Number(s):
SAND2006-5855
TRN: US200625%%345
DOE Contract Number:
AC04-94AL85000
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
47 OTHER INSTRUMENTATION; ANTENNAS; DATA PROCESSING; OPTICAL RADAR; TIME DELAY; Phased array antennas.; Signals and signaling.; Synthetic Aperture Radar.

Citation Formats

Doerry, Armin Walter. SAR processing with stepped chirps and phased array antennas.. United States: N. p., 2006. Web. doi:10.2172/893561.
Doerry, Armin Walter. SAR processing with stepped chirps and phased array antennas.. United States. doi:10.2172/893561.
Doerry, Armin Walter. 2006. "SAR processing with stepped chirps and phased array antennas.". United States. doi:10.2172/893561. https://www.osti.gov/servlets/purl/893561.
@article{osti_893561,
title = {SAR processing with stepped chirps and phased array antennas.},
author = {Doerry, Armin Walter},
abstractNote = {Wideband radar signals are problematic for phased array antennas. Wideband radar signals can be generated from series or groups of narrow-band signals centered at different frequencies. An equivalent wideband LFM chirp can be assembled from lesser-bandwidth chirp segments in the data processing. The chirp segments can be transmitted as separate narrow-band pulses, each with their own steering phase operation. This overcomes the problematic dilemma of steering wideband chirps with phase shifters alone, that is, without true time-delay elements.},
doi = {10.2172/893561},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2006,
month = 9
}

Technical Report:

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  • A ceramic ferroelectric phase shifting device has been demonstrated using Ba(1-x)Sr(x)TiO3 (BSTO) ceramics. As a part of an effort to optimize the electronic device performance in the phase shifter, various composites of BSTO combined with other nonelectrically active oxide ceramics have been formulated. In general, the composites have reduced dielectric constants, epsilon`, where epsilon = epsilon` = i(epsilon)`, and loss tangents, tan delta. The low dielectric constant and low loss tangent reduce the overall impedance mismatch and the insertion loss of the device, In addition, the overall tunability, change in the dielectric constant with applied voltage, is maintained at amore » relatively high level. The combination of electronic properties of these materials offer substantially higher operating frequencies, 10 GHz and above. Another application for one of the composites is for use as a capacitor-varistor surge protector. The microstructures including grain size and phase analysis have been examined using SEM and X-ray diffraction. The analysis of the phase formation, compositional variations, and grain size will be related to the electronic properties of the materials.« less
  • Application of Taylor weighting (taper) to an antenna aperture can achieve low peak sidelobes, but combining the Taylor weighting with quantized attenuators and phase shifters at each radiating element will impact the performance of a phased-array antenna. An examination of array performance is undertaken from the simple point of view of the characteristics of the array factor. Design rules and guidelines for determining the Taylor-weighting parameters, the number of bits required for the digital phase shifter, and the dynamic range and number of bits required for the digital attenuator are developed. For a radar application, when each element is fedmore » directly from a transmit/receive module, the total power radiated by the array will be reduced as a result of the taper. Consequently, the issue of whether to apply the taper on both transmit and receive configurations, or only on the receive configuration is examined with respect to two-way sidelobe performance.« less
  • The phased-array antenna will be examined from the point of view of effects caused by changes in frequency. Both simple linear arrays and the more complex conformal array are examined. For the conformal array, a comparison between a corporate-feed structure and a row series-feed structure is included. There are two primary effects which will be discussed: beam-pointing errors and distortion of large bandwidth signals. A formula for estimating the operating or tunable array bandwidth for narrow-bandwidth signals is derived. An expression for the wide-bandwidth-signal transfer function is also obtained and examined. It will be shown that the transfer function dependsmore » both on the array scan angle and the position within the mainbeam. 25 figs.« less
  • These proceedings contain 39 papers grouped under the headings of: High frequency laser sources; High speed/high frequency optical components; Radiating and control elements; Architectures and algorithms; Signal processors 1; Signal processor 11; Optically controlled phased-array antennas 1; Optically controlled phased-array antennas 11.