Deployable Helical
Antenna for Nano-
Satellites
Wednesday August 6th 2014,
Author: Daniel Ochoa Product Development Manager, Astro Aerospace
28th AIAA/USU Small Sat Conference
SSC14-IX-4
Co-authors: Kenny Hummer, Mike Ciffone
Patent Pending
Cleared for public release; distribution unlimited. NGAS Case 14-1613 dated 8/11/14.
Astro Aerospace – Carpinteria, CA
Cleared for public release; distribution unlimited. NGAS Case 14-1613 dated 8/11/14.
www.northropgrumman.com/Astro
twitter: @astroaerospace
Astro Aerospace
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Since 1958 Astro Aerospace has helped enable complex missions to Earth orbit, Mars, and beyond with innovative deployable structures and mechanisms
– AstroMesh® Mesh Antenna Reflector
– Storable Tubular Extendable Member (STEM™)
– Telescopic Booms
– Hinges and Mechanisms
Hundreds of flights – Zero Failures – Voyager
– Mars Pathfinder
– ISS Mobile Transporter
– Inmarsat 4
– Alphasat
– 2014 Launch Pending: Soil Moisture Active Passive (SMAP)
Deployable Helical Antenna
At least a portion of the technology which is discussed in this paper is the subject of one or more pending patent applications, including but not limited to US Application No. 13/564,393, EU Application No. 13003752.6-1812.
Cleared for public release; distribution unlimited. NGAS Case 14-1613 dated 8/11/14.
Background and Need
A Deployable 10dBi UHF Antenna makes >1Mbps Links Feasible
5
Type Description Developer Figures
Deployable
UHF/VHF
CubeSat
antenna. Deploys 4
monopole
antennae
Max Power:
2W
Mass: 0.10 kg
Innovative
Solutions in Space,
Netherlands
Deployable
High Gain Antenna
CubeSat
Parabolic antenna
Max gain: 18 dBi
Mass: 1.0 kg
BDS
Phantomworks (USA)
Deployable
High Gain
Antenna
CubeSat
Parabolic
antenna
Max gain: 15 dBi
Half Angle: 1.1°
Mass: 1.0 kg
USC Space
Engineering
Research
Center (SERC),
USA
• CubeSats for low cost/scalable
SATCOM missions
– Small Sat Mission Innovation requires
RF performance
– User Ground radios are portable and
rely on omni-directional antennas
– UHF amateur radio link rates are
limited to the 100Kbps range by 0dBi
gain antennas typically used
• Small Sat High Gain Antenna
Options are Limited
– Real estate is at a premium - The
CubeSat form factor is limiting
– Power is limited
C. Frost. And E. Agasid et al, “Small Spacecraft Technology Sate of the Art,” NASA/TP-2014-216648,
Ames Research Center, Moffett Field, CA, January 2014.
Cleared for public release; distribution unlimited. NGAS Case 14-1613 dated 8/11/14.
System Overview
6 Cleared for public release; distribution unlimited. NGAS Case 14-1613 dated 8/11/14.
Mechanical Design
• Helix
– S-2 glass /PEEK thermoplastic pultruded
tape strips, .010-inch thick, .625-inch wide
– 3.5 mil conductive copper tape as RF
conductor
– Intersections joined with ultrasonic welding
– Deployed Form
• 5 helical turns
• 14.5-inch diameter.
• 12° pitch,
• 54.33-inch tall
• Top is terminated with conical neck
down
– Stowed Form
• Coiled and rolled into an approximate
0.5U volume
– Deployment is strain energy driven
7 Cleared for public release; distribution unlimited. NGAS Case 14-1613 dated 8/11/14.
Mechanical Design cont.
• Ground Plane
– Single layer, aluminized Kapton
– Stiffened with four 0.032-inch diameter
fiberglass epoxy rods anchored to small
aluminum disk core
– Deployed Form
• 24-inch x 24 inch square
– Stowed Form
• Spiral wrapped around core
– Deployment is strain energy driven
8 Cleared for public release; distribution unlimited. NGAS Case 14-1613 dated 8/11/14.
Helix Stow Process
9
650% Speed
Cleared for public release; distribution unlimited. NGAS Case 14-1613 dated 8/11/14.
Helix Stow Process cont.
10
Mid Stow
Full Stow
Cleared for public release; distribution unlimited. NGAS Case 14-1613 dated 8/11/14.
Helix Deployment
250 frames/second speed
11 Cleared for public release; distribution unlimited. NGAS Case 14-1613 dated 8/11/14.
Helix Deployment cont.
12 Cleared for public release; distribution unlimited. NGAS Case 14-1613 dated 8/11/14.
Modal Analysis
• FEMAP/Nastran
• 1st Mode
– Buckles about prime vertical
stiffener attached to baseplate
• 2nd Mode
– Twist about prime vertical stiffener
• 3rd Mode
– Expansion and contraction
“pumping motion” about Z-axis
13
Mode Frequency (Hz) Figure
1st 0.1839
2nd 0.2593
3rd 1.3334
Cleared for public release; distribution unlimited. NGAS Case 14-1613 dated 8/11/14.
RF Design and Test
• 5 turn helix chosen in early trades
to provide desired gain, beam
width, and circular polarization
• 2 turn taper added to improve the
axial ratio
• Tested in anechoic chamber with
support frame and representative
ground plane
• Test setup circuits Impedance
matched to helix within 50 ohms
14
Cleared for public release; distribution unlimited. NGAS Case 14-1613 dated 8/11/14.
RF Performance
Voltage Standing Wave (VSWR) ≤ 1.5:1 15
Cleared for public release; distribution unlimited. NGAS Case 14-1613 dated 8/11/14.
RF Performance cont.
Full contour measured every 1 MHz, 200 to 500 MHz 16
-30
-25
-20
-15
-10
-5
0
5
10
15
-140 -120 -100 -80 -60 -40 -20 0 20 40 60 80 100 120 140
Dir
ect
ive
Gai
n (
dB
ic)
Angle (deg)
Co-pol Pattern, phi = 90 deg, Fiberglass Tape Sox Proof of Concept
300 MHz
310 MHz
320 MHz
330 MHz
340 MHz
350 MHz
360 MHz
370 MHz
380 MHz
390 MHz
400 MHz
Cleared for public release; distribution unlimited. NGAS Case 14-1613 dated 8/11/14.
RF Performance cont.
Excellent axial ratio ≤ 2.0 dB from 250 MHz to 470 MHz 17
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
0.20 0.22 0.24 0.26 0.28 0.30 0.32 0.34 0.36 0.38 0.40 0.42 0.44 0.46 0.48 0.50
Axi
al R
atio
(d
Bic
)
Frequency (GHz)
Boresight Axial Ratio of Proof Of Concept Fiberglass Tape Helix (RHCP)
Cleared for public release; distribution unlimited. NGAS Case 14-1613 dated 8/11/14.
RF Performance cont.
Loss is less than -1.5 dB from 260 MHz to 400 MHz
18
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
0.20 0.22 0.24 0.26 0.28 0.30 0.32 0.34 0.36 0.38 0.40
Dir
ect
ivit
y (d
Bic
)
Frequency (GHz)
Boresight Directivity of Proof Of Concept Fiberglass Tape Helix (RHCP)
Directivity
Gain
Cleared for public release; distribution unlimited. NGAS Case 14-1613 dated 8/11/14.
Mission Implementation
• The 300:1 ratio
deployed volume
to allowable
stowed package
• UHF antenna
provides the
required gain to
close
communication
link budget
19
Solar Array
Payload Electronics
Compartment (1U)
Ground Plane
UHF Helix Antenna
Stowed Helix Compartment (0.5U)
CubeSat Bus (1.5U)
A 0.5U Stowed Antenna allows for full 1U Radio Payload on a 3U CubeSat System
Cleared for public release; distribution unlimited. NGAS Case 14-1613 dated 8/11/14.
Summary
Innovative ultra-compact mechanical design (300:1 volume ratio) can be scaled to required applications for future nano and microsatellites missions
• RF performance is excellent:
– 13 dBi at approximately 400 Mhz
– Axial ratio ≤ 2.0 dB from 250 MHz to 470 MHz
• Further Development
– Stowed package containment and mechanized release
– RF testing with deployable ground plane
– Ground deployment or microgravity (reduced gravity aircraft) testing
20
Cleared for public release; distribution unlimited. NGAS Case 14-1613 dated 8/11/14.
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