potenziale applicativo per lo spazio - italian space agency · potenziale applicativo per lo spazio...
TRANSCRIPT
Antenne a metasuperfice modulata Potenziale applicativo per lo spazio
Toward a revolution in antennas?
Overview
Modulated metasurface antennas are undoubtedly a new area of development in the antenna field.
The European Space Agency is active in this area since many years and this presentation focuses on the following points:
• Background
• Motivations
• Current status
• Perspectives
Historical background
1. Oliner seminal work (1959)
2. Holographic antennasa. Checcacci, P.; Russo, V.; Scheggi, A., “Holographic antennas”, IEEE Trans.
Antennas Propag., Volume: 18 , Issue: 6, Year: 1970 , Page(s): 811 – 813
b. Iizuka, K.; Mizusawa, M.; Urasaki, S.; Ushigome, H., “Volume-type holographicantenna”, IEEE Trans. Antennas Propag., Volume: 23 , Issue: 6, Year: 1975, Page(s): 807 – 810
3. Frequency sensitive surfaces
4. Photonic bandgap structures
5. Metamaterials
Holographic antennas
Checcacci (1970) Iizuka (1975) Elsherbiny (2004)
Università di Siena (2006-2010)
May years after Oliner’swork, some application of its idea to antennas started to surface.
Current R&D landscape
• USA
Sievenpiper, Colburn (UCSD), Grbic (Umich), Smith (Duke)
Mostly concentrated on electronic scanning with -pixel control, large number of patents
• Europe
Maci, Martini, Caminita - Università di SienaVecchi, Matekovitz - Politecnico di TorinoFreni – Università di FirenzeDe Vita – IDS Ingegeneria dei SistemiCasaletti - Université de Paris 6Sauleau, Ettorre - Université de RennesGomez, Tornero - Universidad Politécnica de CartagenaRajo Iglesias - Universidad Carlos Terciero MadridNeto, Lombard - Technische Universiteit DelftLuukkonen, Treviakov - TKK Helsinki Sabbadini, Minatti – ESA-ESTEC
Patent US20120194399
Key motivations: strategic
The space sector appears to be lowering its growth rate, while global competition increases as the offer from emerging countries grows.
As a consequence, the need for cost reduction to maintain European Industry competitiveness becomes stronger and stronger.
An increase in modularity and design reusability, without compromising performances is therefore very desirable.
Key motivations: programmatic
Matematerials and metasurfaceshave been the object of extensive research over past decades.
Today, the application of (modulated) metasurfaces to antennas is quickly gaining momentum and the application potential appears to be large.
Conjugate-Matched Metasurface AntennasThe trend toward miniaturisation to reduce mass and envelop (and cost) for a same type of mission is strong.Antennas are a well known and somewhat distressing example of the opposite tendency.Yet, the challenge to at leastsave mass and reduce cost isthere needs to be answered.
Key motivations: technologic
Conjugate-Matched Metasurface Antennas• Use sub-wavelength features to gain control of surface
impedance at antenna boundaries• Exploit the added freedom for improved solutions
The modulated metasurface answer
ESA Technology developments
A number of activities have produced promising results so far other sare being started
1. Innovative Planar Highly Directive Antenna Based on Artificial SurfacesLEO X-band Data downlink (IDS, UniSi, UniFi)
2. Scalable low-mass low-envelope high-to-very-high gain antennaScience and Exploration HGA X-ban (IDS, UniSi, TASI)
3. Shared aperture reflector antennaShaped-reflector antenna enhancement (Ticra, UniSi)
4. Biomass calibration radar transponder assessmentStudy of a metasurface-enhanced array solution (ESA, Wave Up, UniSi)
5. Beam shaping by surface impedance controlTelecom antenna solutions using curved metasurfaces (UniSi, IDS, MVI, Ticra)
6. Thin metasurface lensesStudy of metasurface lenses to enhance reflector antennas (UniSi, Wave Up, ESA)
X-band data downlink from LEO
Isoflux pattern: uniform power density at the Earth surface.
Bandwidth: 8.5-8.7 GHz.
Polarization: circular.
Cross polar: lower than -6dB.
High-gain antennas
Very similar behaviour and two very different technologies
The strong gain reduction is due to the high losses of dielectric used for the second antenna (ABS !)
Array enhancement
Reduce complexity by replacing the tapered portion of an array for very low-sidelobe and cross-polar with a metasurface
0 0.5 1 1.5 2 2.5 3 3.5 40
0.2
0.4
0.6
0.8
1
1.2
1.4
/Lambda
Aperture Distribution
-90 -75 -60 -45 -30 -15 0 15 30 45 60 75 90-60
-50
-40
-30
-20
-10
0
10
20
30
[Deg]
dBi
Directivity
Aperture distribution
Antenna directivity
-0.04
-0.02
0
0.02
0.04
-0.02
0
0.02
0123
x 10-3
Severe beam degradations!
MetaReflector concept
A metasurface reduces scan aberrations by improving beam collimation
Enhanced avionics antennas
Miniaturised X-band TT&C antenna25×25×33 mm (ESA study)
Pattern control and interference reduction
Improved beam shape
The use of a metasurface allows a better control of the antenna pattern adding very little complexity.
Metasurfing and meta-lenses
Use metasurface to guide the surface wave or to shape a space wave
adding further freedom.
Many applications can be envisaged:
• Taper control in FSS reflectors
• Beam formers
• Improved radome performances
• RF-Enhanced thermal blankets
A robust design methodology
A complete design procedure has been developed and validated covering all steps from initial sizing to accurate performance assessment and a patent application filed by ESA.
Several possible implementations
Besides the ones shown so far, several other implementation options exists, ranging from fully metallic to purely dielectric structures and all their possible combinations.
Also combinations with variable materials, e.g. nematic crystals are known to be in principle feasible.
While at least for on-board solutions, the simplest solutions remain the most promising, wide-range exploration is useful to fully assess the potential.
Pin bed Printed elements
Modulated dielectric Multi-layer grid
More possibilities…
A.J. Martinez-Ros, J.L. Gomez-Tornero, G. Goussetis - IEEE AP
Not really a metasurface: a metaline ?
A rough technology map
1 10 100 f (GHz)
0.1
1
Size(m)
2“Printed circuit”
Filled honeycomb
Shaped dielectricMetal-only
Interwoven dielectrics
3D printing
Sandwich technologies
Optical technologies
Main achievement (so far)
The feasibility of a new flexible antenna technology has been demonstrated.
The first examples offer ultra-thin and lightweight solutions with performances comparable to existing ones.
Open issues
Needless to say there are several open issues, but more important there a few known limitations:
• Multiband structures are not easy to obtain
• Aperture efficiency is as yet suboptimal
• Design procedure implementation limited to printed structures
• Design optimisation tools have limited reach owing to complexity
Value for space applications
Modulated metasurfaces antennas:
• Are applicable to several antenna architectures
• Result in products based on already available technologies
• Have a potential for performance improvement in several area• Direct pattern and polarisation control• Low-envelope, low-complexity, low-mass alternative in many cases• First design and performance estimate very close to final solution
• Allow single-qualification multiple-missions customisable antennas• The same basic design can be used for many antenna patterns• A small range of antennas could cover common space-systems needs• Only RF testing required, plus possibly a delta-qualification
• Are amenable to dynamic re-configuration…
Metasurface Antennas in Space
Several applications of modulated metasurface antennas are conceivable in the space sector, for instance:
Space segment
• LEO Data downlink, mainly for Earth Observation – feasibility proven• HGA for Science and Exploration missions – under development• Aperture sharing for shaped reflector antennas for Telecomms - started• Compact “reflector antennas”, mainly TLC (EO, Science, Expl.) - started• Horns and beam formers (TLC, EO) – started (horns)• Beam-shaping frequency or polarisation selective screens (TLC)• SAR antenna panels, Sounder antennas (EO)• Navigation transmit antennas (NAV)
Ground segment
• Narrow-beam satellite ground terminals (portable and mobile)• TVRO • GNSS high-end receivers
Configuration mapping
Metasurface configuration
Applications
Science EO Telecom Navigation
Flat panel fed in plane (holographic) HGA PDHT Payload Tx antenna
Array SAR Payload
Lens antennas Radar Payload
Integrated in thermal blanket LGA TT&C
Reflector antenna Radar Payload
Panel with metasurface feeder MGA Terminal Rx antenna
Curved panel fed in plane PDHT Terminal
Horn with metasurface walls (also outside) MGA Payload
Metasurface cup with (metasurface) feeder MGA Terminal
Helix equivalent MGA TT&C TT&C
Conical/cylindrical antenna MGA TT&C
Bicone equivalent TT&C
Faceted antenna HGA
Cradle-like array SAR Payload
Lens-based BFN Payload
ESA activities
0102 0304 05 06 070809 101112
201101 02 0304 0506 07 0809 1011 12
20120102 030405 06070809 1011 12
201301 02 0304 05 0607 08091011 12
20140102 030405 06 070809 101112
2015
Running In TRP Plan In ARTES Plan Fund request
Low mass and volume X-band HGA for Exploration
Innovative Planar Highly Directive Antenna Based on Artificial
Surfaces
Meta-reflectors
Assessment of Metasurface
Antenna Configuration,
Technology and Implementation
Meta-horns
Antennas based on metasurface facets
Antennas based on (highly) curved metasurfaces
Shared aperture reflector antenna
Beam shaping by surface impedance control
Scalable low-mass low-envelope high-to-very-high gain antenna
Conjugate-Matching Antenna Design Tool
Metasurface Characterisation Methodology
In GSTP Plan In other plans
0102 030405 06 070809 101112
2016
Engineering model of X-band HGA for Exploration
Engineering model of isoflux antenna for LEO
0102 0304 05 06 070809 101112
2017
Low-complexity data downlink antenna
AMC/Metamaterial Antennas for Broadband Connectivity
Beam-scanning metasurface antennas(Internal research fellowship)
Metasurface Antenna Potential and Tecnhology Assessment (Internal work)
Conjugate-Matched Metasurface Enhanced Array
Meta-lenses
Completed Intended
Thin Metasurface Lenses (external Post-doc)
Meta-arrays
Other related research areas at ESA
The Agency is also actively pursuing technology developments in neighbouring areas, like:
• Artificial Magnetic Conductors in antennas
• Millimiter-wave metamaterial lenses (multilayer metasurfaces)
• Active surfaces (uniform metasurfaces with active elements)
• Metamaterial waveguides
Conclusions
It is possible todesign the boundary condition at
the antenna surfaceinstead of
adjusting the antenna shape to exploit a fixed boundary condition
leading to significant advantages