LEO-BEaNS: a phasedarray Ka-band CubeSat
constellation PNTsolution with the goalof increased reliability
Photo by Stefan Els

The Team• Dirk Slabber• Tian Cilliers (me)• Lauren Cooke• Jurgen van der Merwe• Sa’ad Badat• Mikayla Isebeck• Phillip Lotriet• Rowan Twilley
Engineering · EyobuNjineli · Ingenieurswese

Problems with GNSS

• Low amount of satellites• Multipath error• Foliage cover• Atmospheric interference

Engineering · EyobuNjineli · Ingenieurswese

Mission Objectives and PerformanceParameters• Transmit a novel positioning, navigation and timing (PNT) signal from mission
satellites• Do this in a frequency band less susceptible to ionospheric scintillation andmulti-path error• Increase the number of satellites visible from any point• Achieve sufficient signal-to-noise ratio (SNR) for reception• Reduce the cost per satellite when compared to traditional GNSS solutions

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Concept of Operations• Constellation of 6U CubeSats in LEO
receives data from existing GNSS
satellites in L-band• Used to calculate position and clockdrift• LEO constellation transmits a custom
Ka-band PNT signal• Done via a phased-array antenna toreduce power requirements

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Satellite System Overview

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Phased Array Antenna• Custom part proposed• Electronically steered and swept over servicearea• 24 by 24 grid of elements with 30 dB Chebyshev
tapering• Integrated with TDMA
• Allows for higher directivity and reduced power
consumption• Allows for selectively allocated availability

Engineering · EyobuNjineli · IngenieursweseOther Components• ISISpace 90 Wh EPS and OBC• CubeSpace CubeADCS• CludeSpace GNSS receiver and UHF/VHF transceiver• Enpulsion Nano FEEP Thruster• ISISpace Deployable Solar Panels• Aurora Propulsion Systems plasma brake• See full paper for power and link budgets

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Orbit Design• Altitude of 1000 km chosen as trade-off
between radiation, delta-V requirement andservice area

• Walker-Delta layout, 18 planes, 7 satellites
per plane for a total of 126• Inclination of 49.1 degrees• Ensures between 5 and 13 satellites visible
for locations within +-60 degrees latitude• Monte-Carlo simulation done to estimate
GDOP: <4 for chosen latitudes
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Geometric Dilution of Precision

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In-Orbit Operations• Launch to 300 km by 1000 km orbit to passively deorbit failing satellites• Use Enpulsion Nano system to raise perigee and phase RAAN over roughly a year
• Use this system for collision avoidance over lifespan of satellite• Drop perigee back down for reentry at end-of-life• Total delta-V of 570 m/s divided between 370 m/s for orbit raise/lower and 200
m/s for collision avoidanceEngineering · EyobuNjineli · IngenieursweseImplementation Plan
• Proposed to execute mission in three phases• Develop a single satellite in a university context as proof of concept• Build and launch a small number of satellites to confirm functionality• Continue to launch new satellites to maintain and grow constellation

Engineering · EyobuNjineli · Ingenieurswese

Mission Risks• Regulatory hurdles• Funding difficulty• Technical problems related to extreme timing precision required• In-orbit failure of satellites• Operational problems

Engineering · EyobuNjineli · Ingenieurswese

Summary• Novel solution proposed for enhancing GNSS reliability• Ka-band transmissions should be more resistant to ionospheric scintillations andobstruction• Phased array allows for broad coverage angles and low power use• This allows the solution to be scaled down to CubeSat size and significantly
decreases deployment cost
• Offers a forward-looking strategy to address PNT demands of moderntechnology, urbanization, and rapid humanitarian response

Engineering · EyobuNjineli · Ingenieurswese

Thank you
EnkosiDankieEngineering · EyobuNjineli · Ingenieurswese

Photo by Stefan Els