Deployable Helical Antenna for Nano-Satellites

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


www.northropgrumman.com/Astro

twitter: @astroaerospace

http://www.northropgrumman.com/Astro

Astro Aerospace

3

Use this space to communicate your key takeaway (or remove)

Mark pages according to the proprietary level of information as described in Company Procedure J103 (or remove)

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.


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.


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


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


Helix Stow Process

9

650% Speed


Helix Stow Process cont.

10

Mid Stow

Full Stow


Helix Deployment

250 frames/second speed


Helix Deployment cont.


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


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


RF Performance

Voltage Standing Wave (VSWR) ≤ 1.5:1 15


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



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)



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


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


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


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Deployable Helical Antenna for Nano-Satellites

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