IEEE Aerospace and Electronic Systems Magazine - July 2020 - 50

Space Phased Array Antenna Developments: A Perspective on Structural Design

Figure 3.
Diagram of honeycomb sandwich panel.

antennas: folded planar array antennas and flexible array
antennas. According to [52], the phased array antenna
contributes more than 80% of the satellite payload weight.
Therefore, the antenna structure is the focus of weight
reduction efforts.

LIGHTWEIGHT FOLDED PLANAR ARRAY
The main material of a folded planar array antenna is a
honeycomb sandwich-structure composite material,
which is lightweight, high in strength, malleable, resistant to high temperatures, and can be surfaced precisely
in a simple manufacturing process [53] (see Figure 3).
This material is applied in deployable phased array
antennas in the United States, Europe, Canada, and other
countries. Unfortunately, the aperture of the folded planar array antenna is circumscribed. In other words, the
larger the aperture is, the heavier its weight, which will
burden the satellite system. For example, the weight of
the SIR-C satellite antenna is 900 kg, and the DISCOVER-2 satellite antenna weighs up to 1500 kg. Additionally, the large aperture array demands a complicated
deployment mechanism, which requires a high degree of
reliability.

LIGHTWEIGHT FLEXIBLE ARRAY
The flexible array antenna with a thin film has the advantages of being lightweight, having a small volume, being
easy to fold and unfold, and having high reliability. The
high frequency transmitting and receiving electronic
equipment of antennas are placed in the interior of the
foldable antenna, while the high frequency feeder part on
the back is made flexible and folding. In this way, it can
50

lighten the space active phased array antenna system by
more than three times. According to [54], in comparison
with the folded planar array antenna of the same size, the
mass of the flexible array antennas with a thin film structure is only 1/2-1/5, volume is less than 1/10, and transmission cost is reduced by 1 or 2 orders of magnitude.
The common flexible deployable array antennas have
two types of modes during the launching stage: folded
and crimp contraction. They are deployed by the way of
inflatable expansion or line expansion after entering the
orbit [55].
The JPL has accumulated a lot of technical expertise
in the spaceborne deployment structures. In the early
stages of development, the thin-film array antenna was
the L-band SAR antenna array (see Figure 4) developed
at the end of 20th century by cooperation between JPL,
the ILC Dover Company, and the L'Garde Company
[56]. The surface density of this antenna was as low as
1:7 kg=m2 . In 2003, JPL developed an antenna structure
with T/R components (see Figure 5). In 2008, JPL developed another 3 m Â 5 m active phased array antenna
(see Figure 6). Figure 7 depicts an 3 m Â 100 m active
lens array antenna with an inflatable thin-film. The flexible array antenna with a thin-film structure can operate
at a very high frequency band, which satisfies the
requirements for future spaceborne antenna characteristics (lightweight and large aperture). However, it is difficult to guarantee the high surface accuracy of the large
aperture thin-film antenna array due to the limitation of
materials. In order to acquire a larger aperture and better
surface accuracy, the expanded form of rigid-flexible
combinations is one of the future research directions
about the spaceborne antenna.

IEEE A&E SYSTEMS MAGAZINE

JULY 2020

IEEE Aerospace and Electronic Systems Magazine - July 2020

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