IEEE Aerospace and Electronic Systems Magazine - July 2020 - 46

Space Phased Array Antenna Developments: A Perspective on Structural Design

Figure 1.
Main satellites equipped with active phased array antennas.

The Shuttle Radar Topography Mission (SRTM) project
commenced in August 1996 and ended in March 2001 [20].
It was composed of two deployable antennas (C-band and
X-band), two GPS antennas, three light-emitting diodes
(LED), and corner reflectors. The two deployable antennas
only received radar signals, whereas the main antennas were
responsible for transmitting radar signals. The bandwidth of
the C-band antennas was 10 MHz, and the antenna gain was
up to 42.7 dB. The bandwidth of the X-band antennas was
9.5 MHz, and the gain was up to 44.5 dB. The control rod of
antennas was made up of 87 cubic frame components, with
an aperture size of 1.12 m and a weight of 290 kg. Its
extended length could reach up to 60 m. During takeoff and
landing, the antenna control rod was mounted in a metal
can and the antenna was driven by a motor to be deployed
in space.
From 1997 to 1998, the Iridium LLC Company
launched 66 artificial satellites for mobile global communications. All the antennas used L-band microstrip active
phased array antennas [21], each of which included three
active phased array boards. Each board included 106
transceiver units, which could provide 16 point beams.
Accordingly, three arrays produced a total number of 48
beams covering an angle of Æ 45 . Each board used two
heat conduction pipes attached to the bottom plate of each
T/R component.
Global Star [22] deployed 44 satellites over the course
of 11 launches in 1999, and in the first quarter of 2000 it
launched another 4 satellites. Their phased array antenna
consisted of a transmitting array and a receiving array
arranged on the same plane, which faced the ground (see
Figure 2). The S-band transmitting array consisted of 91
elements, and the L-band receiving array was composed
46

of 61 elements. They were both arranged in a hexagon,
and the element spacing is 0.6 times the wavelength. The
T/R module was connected to the rear of the radiating
element.
The LIGHT-SAR, launched in September 2002, was a
lightweight SAR technology developed by NASA's Jet
Propulsion Laboratory. The satellite mainly used the Lband active phased array antennas, whose bandwidth was
150 MHz and resolution was up to 3 m [23]. The goal of
LIGHT-SAR was to reduce the cost of SAR deployment
and to improve the quality of data with the use of
advanced technology.
The Discovery II project began in February 1998 and
ended in 2010, which was a joint project developed by the
United States Air Force, Defense Advanced Research
Projects Agency, and National Intelligence Agency [24].
The X-band active phased array antenna loaded on the satellite had four operating modes: stripmap, spotlight, scanning, and ground moving target indication (GMTI). The
antenna elements were 2800 in total and the pointing accuracy was up to 0.02 .

Figure 2.
Antenna placement of Global Star.

IEEE A&E SYSTEMS MAGAZINE

JULY 2020

IEEE Aerospace and Electronic Systems Magazine - July 2020

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