IEEE - Aerospace and Electronic Systems - January 2023 - 22

Feature Article:
DOI. No. 10.1109/MAES.2022.3216263
Synthetic Aperture Radar During the 50 Years of the
Aerospace and Electronic Systems Society
Michael Inggs , University of Cape Town, Rondebosch 7701, South Africa
INTRODUCTION
This article is a light overview of synthetic aperture radar
(SAR) over the last 50 years. It is not a thorough, totally
inclusive, review, and is largely, nontechnical, with a nod
to the multidisciplinary readership of our society and its
magazine. A large number of contributors and their systems
have had to be glossed over, in favor of wide coverage,
and a bias due to the author's experience in SAR.
Quoting a forgotten source, " Radar is the champagne of
Electronics " means, to me, SARmust be the, " single malt of
radar. " It is an exciting mix of technology, spanning microwaves,
through digital technology, to rich applications in
Earth and planetary science. Kramer [1] is an encyclopedic
overview of past and present sensor systems. To complete
this part ofthis article, the " What is SAR? " section provides
a briefoverview ofsome ofthe applications ofSAR.
A light introduction to SAR image formation (see the
" What is SAR? " section) follows, and includes what has
unfolded in the last 50 years, with the last five years
almost a blur, given the explosion of activity. The historical
background (see the " Prehistory " section) to the development
of this technology, is perhaps best understood
with the work in holography by Gabor [2], although its initial
development was from a more practical than theoretical
basis (Carl Wiley at Goodyear Aerospace [3]). Due to
restrictions on open publication, this article is light on military
applications and systems, although the origins of
much ofSAR technology lies in government funding.
The earliest implementations of SAR were using airborne
platforms and we review some of the first implementations
mostly based in the United States (see the
" Airborne Achievements " section), but quickly spreading
to other nations (Germany, France, etc.). Much of this
Author's current address: Michael Inggs is with the
University of Cape Town, Rondebosch 7701, South
Africa (e-mail: mikings@gmail.com).
Manuscript received 14 August 2022; accepted 10
October 2022, and ready for publication 2 November
2022.
Review handled by Hugh Griffiths.
0885-8985/22/$26.00 ß 2022 IEEE
22
early work was of course inspired by the use for military
applications, but the recent growth in SAR is fueled by
Earth and planetary applications.
Placing SAR sensors in space was the next logical step
and before the formation of our society. Project Quill [4]
was probably the first, but much of the results are lost.
Amazingly, planetary exploration of the moon and planets
using radar was an early achievement (Venus, Goldstone,
etc.). The first notable Earth observation SAR was Seasat
(see Figure 1), launched by NASA in 1978 [5] and, in its
very short life of about 110 days, confirmed the excitement
of the science community as to the usefulness of this
new technology.
Moving on, the early spaceborne systems were massive
in size and the domain of the major space agencies,
we present some of these early systems (see the section
" Move to Space: The Behemoths " ) that continued to add
Figure 1.
World's first dedicated oceanographic imaging radar, Seasat.
Operated at L band for 110 days in 1978 [6].
IEEE A&E SYSTEMS MAGAZINE
JANUARY 2023
https://orcid.org/0000-0003-2162-7710
IEEE - Aerospace and Electronic Systems - January 2023

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