Deployable Helical
Antenna for NanoSatellites
Patent Pending
28th AIAA/USU Small Sat Conference
Wednesday August 6th 2014,
Author: Daniel Ochoa
Product Development Manager, Astro Aerospace
Co-authors: Kenny Hummer, Mike Ciffone
SSC14-IX-4
Astro Aerospace – Carpinteria, CA
www.northropgrumman.com/Astro
twitter: @astroaerospace
Astro Aerospace
Since 1958 Astro Aerospace has helped enable
complex missions to Earth’s 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
Use this space to communicate your
key takeaway (or remove)
3
– 2014 Launch Pending: Soil Moisture Active Passive
(SMAP)
Astro Aerospace
Mark pages according to the proprietary level of information as described in Company Procedure J103 (or remove)
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.
Background and Need
Type
Description
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
Developer
Figures
• 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.
A Deployable 10dBi UHF Antenna makes >1Mbps Links Feasible
5
Astro Aerospace
System Overview
6
Astro Aerospace
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
Astro Aerospace
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
Astro Aerospace
Helix Stow Process
650% Speed
9
Astro Aerospace
Helix Stow Process cont.
Mid Stow
Full Stow
10
Astro Aerospace
Helix Deployment
250 frames/second speed
11
Astro Aerospace
Helix Deployment cont.
12
Astro Aerospace
Modal Analysis
Mode
Frequency (Hz)
1st
0.1839
Figure
• FEMAP/Nastran
• 1st Mode
– Buckles about prime vertical
stiffener attached to baseplate
• 2nd Mode
2nd
0.2593
– Twist about prime vertical stiffener
• 3rd Mode
– Expansion and contraction
“pumping motion” about Z-axis
3rd
13
1.3334
Astro Aerospace
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
Astro Aerospace
RF Performance
Voltage Standing Wave (VSWR) ≤ 1.5:1
15
Astro Aerospace
RF Performance cont.
Co-pol Pattern, phi = 90 deg, Fiberglass Tape Sox Proof of Concept
15
10
Directive Gain (dBic)
5
300 MHz
310 MHz
0
320 MHz
330 MHz
-5
340 MHz
-10
350 MHz
360 MHz
-15
370 MHz
380 MHz
-20
390 MHz
400 MHz
-25
-30
-140 -120 -100
-80
-60
-40
-20
0
20
Angle (deg)
40
60
80
100
120
140
Full contour measured every 1 MHz, 200 to 500 MHz
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Astro Aerospace
RF Performance cont.
Boresight Axial Ratio of Proof Of Concept Fiberglass Tape Helix (RHCP)
5.0
4.5
4.0
Axial Ratio (dBic)
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
17
0.20
0.22
0.24
0.26
0.28
0.30
0.32 0.34 0.36 0.38
Frequency (GHz)
0.40
0.42
0.44
0.46
0.48
0.50
Excellent axial ratio ≤ 2.0 dB from 250 MHz to 470 MHz
Astro Aerospace
RF Performance cont.
Boresight Directivity of Proof Of Concept Fiberglass Tape Helix (RHCP)
14
13
12
11
Directivity (dBic)
10
9
8
7
Directivity
6
Gain
5
4
3
2
1
0
0.20
0.22
0.24
0.26
0.28
0.30
0.32
Frequency (GHz)
0.34
0.36
0.38
0.40
Loss is less than -1.5 dB from 260 MHz to 400 MHz
18
Astro Aerospace
Mission Implementation
• The 300:1 ratio
deployed volume
to allowable
stowed package
• UHF antenna
provides the
required gain to
close
communication
link budget
UHF Helix Antenna
CubeSat Bus (1.5U)
Solar Array
Ground Plane
Payload Electronics
Compartment (1U)
Stowed Helix Compartment (0.5U)
A 0.5U Stowed Antenna allows for full 1U Radio Payload on a 3U CubeSat System
19
Astro Aerospace
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
Astro Aerospace