The International Union of Radio Science URSI

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The International Union of Radio Science (URSI)
Modern Radio Science - An Overview of URSI
Activities Kristian Schlegel Max-Planck-Institut
für Aeronomie Katlenburg-Lindau, Germany
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The International Union of Radio Science (URSI)

• Founded 1913/1919, non-governmental, non-profit
• One of 27 scientific Unions in ICSU
  (International Council for Science)
• 44 nations/regions are members
• Objectives Knowledge and study of all aspects of
  EM fields and waves
• International stimulation and coordination
• Studies
• Research
• Applications
• Scientific exchange
• Communication

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URSI Scientific Commissions A.
Electromagnetic Metrology

• Measurements and standards in time and frequency,
  from DC to optical frequencies, e.g.
• Atomic Clocks (?t/t ? 10-15 s)
• RF-Frequency Standards
• Optical frequency Standards
• Dosimetry of RF Radiation
• Quantum metrology and electrical methods in
  fundamental constants

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Electromagnetic MetrologyOptical Frequency
Standards
Femtosecond Laser as Frequency Comb Generator
A train of periodic femtosec laserpulses yield a
comb of lines equally spaced in the frequency
domain. The relative phase offset between the
pulses, ?CEO, has to be compensated by by a phase
coherent link between the modulation frequency
and the carrier frequency of the laser.
(from Telle)
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Electromagnetic MetrologyOptical Frequency
Standards

• This (RF) method achieves frequency synthesis
  with accuracies ??/? ? 10-15 in part of the
  visible and near infrared range.
• Some possible applications
• Ultrastable microwave signals (e.g. for Doppler
  Radars)
• Checking the stability of fundamental constants
  ( e.g. ?)
• Probing the dynamics of single electrons in
  interior shells of elements (e.g. Science,
  February 6, 2004, pp 813-815)
• Scientist are working to extend this methods
  using atto-second (10-18 s) laser

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URSI Scientific Commissions B. Fields and Waves

• Electromagnetic theory and applications
• Time-domain and frequency-domain phenomena
• Scattering and diffraction
• General propagation including waves in
  specialised media
• Guided waves
• Antennas and radiation
• Inverse scattering.

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Fields and Waves Metamaterials ( MTMs )
Artificial materials that exhibit electromagnetic
responses generally not found in
nature Metamaterials show qualitatively new
response functions that are not observed in the
constituent materials themselves and result, for
instance, from the inclusion of artificially
fabricated, extrinsic, low dimensional structures.
Example Double Negative (DNG) metamaterials ( e
lt 0 and m lt 0) D. Smith et al, UC San Diego
first fabricated a DNG metamaterial with
disjoint SplitRing Resonator and Wire
configuration
(From R. W. Ziolkowski)
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Fields and Waves Metamaterials ( MTMs )
Predicted Electric Field Intensity shows the
negative angle of refraction (NIR)
effect Possible Applications Causal
propagation of signals Time delays in realizing
NIR effects strange lenses Sub-wavelength
focusing
R. W. Ziolkowski
MTMs may lead to new physics and engineering
concepts
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URSI Scientific Commissions C. Radio
Communication Systems and Signal Processing

• Radio-Communication and Telecommunication
  systems
• Spectrum and Medium Utilisation
• Information Theory, Coding, Modulation and
  Detection
• Signal and Image Processing in the area of radio
  science.

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Radio Communication Systems and Signal
ProcessingAdaptive Antennas for Wireless
Communications

• a snapshot is taken of the signals coming from
  all antenna elements, converted to digital form
  and stored
• a DSP analyzes it to obtain an estimate of the
  radio environment identifying users and
  interferers and their location
• the processor calculates the strategy for the
  antenna signals that optimally recovers the
  users signal and rejects the interferers signal
  as much as possible.

(from Delisle et al.)
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URSI Scientific Commissions D. Electronics and
Photonics

• Electronic devices, circuits, systems and
  applications
• Photonic devices, systems and applications
• Micro-electromechanical systems (MEMS)
• Physics, materials, CAD, technology and
  reliability of electronic and photonic devices,
  with particular reference to radio science and
  telecommunications.

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Electronics and Photonics Micro-electromechanic
al systems (MEMS)
Example A Shunt Capacitive Switch By applying a
DC voltage of 6-20 V to the actuation pad it
moves due to electrostatic forces, and thus the
capacitor C is changed
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Electronics and Photonics Micro-electromechanic
al systems (MEMS)
RF MEMS will have a major impact on communication
devices, because they will reduce weight, costs,
size and power dissipation by several order of
magnitudes.
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URSI Scientific Commissions E. Electromagnetic
Noise and Interference

• Terrestrial and sky noise of natural origin
  man-made noise
• The composite noise environment
• The effects of noise on system performance
• The lasting effects of natural and intentional
  emissions on equipment performance
• The scientific basis of noise and interference
  control
• Spectrum management/utilisation and wireless
  telecommunications
• Geo-electric and -magnetic fields and seismic
  associated electromagnetic fields.

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Electromagnetic Noise and Interference Natural
Radio Noise
Sketch of Noise Spectrum
K.S.
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URSI Scientific Commissions F. Wave
Propagation and Remote Sensing

• (a) The study of all frequencies in a non-ionised
  environment (i) wave propagation through
  planetary, neutral atmospheres and surfaces,(ii)
  wave interaction with the planetary surfaces and
  subsurfaces (including land, ocean and
  ice),(iii) characterisation of the environment
  as it affects wave phenomena
• (b) The application of the results of these
  studies, particularly in the areas of remote
  sensing and communications
• (c) The appropriate co-operation with other URSI
  Commissions and other relevant organisations.

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Wave Propagation and Remote SensingMicrowave
techniques for Earth remote sensing two examples
Soil moisture from Brightness obtained with the
ESTAR L-Band Radiometer
Daily Ozone Variation over Lindau obtained with a
Radiometer designed at MPAE
(from Hartogh)
(from Camps and Swift)
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URSI Scientific Commissions G. Ionospheric
Radio and Propagation

• Global morphology and modelling of the
  ionosphere
• Ionospheric space-time variations
• Development of tools and networks needed to
  measure ionospheric properties and trends
• Theory and practice of radio propagation via the
  ionosphere
• Application of ionospheric information to radio
  systems.

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Ionospheric Radio and Propagation Global TEC
Mapping of the Ionosphere
L
(from JPL)
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Ionospheric Radio and Propagation Global TEC
Mapping of the Ionosphere

• Global TEC Data are vital for
• basic ionospheric research
• improving accuracy of navigation systems
• improving operation of HF communications
• assessment of space weather effects
• correction of space weather effects

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URSI Scientific Commissions H. Waves in
Plasmas

• To study waves in plasmas (space and laboratory)
  in the broadest sense, and in particular
• the generation ( i.e. plasma instabilities) and
  propagation of waves in plasmas,
• the interaction between these waves, and
  wave-particle interactions,
• plasma turbulence and chaos,
• spacecraft-plasma interaction.

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Waves in Plasmas Magnetospheric Sounding
The terrestrial magnetosphere houses a broad
variety of different plasmas (in terms of density
and temperature)
Radio Plasma Imager on the IMAGE Satellite 3 kHz
3MHz, max. 40 W, Four 250-m wire
antennas Orbit precession of IMAGE allows the
probing of different regions of the magnetosphere.
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Waves in Plasmas Magnetospheric Sounding
RPI Example Ducted Echoes
(from Burch)
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URSI Scientific Commissions J. Radio Astronomy

• The activities of the Commission are concerned
  with observation and interpretation of all radio
  emissions and reflections from celestial objects.
  
• Emphasis is placed on
• the promotion of technical means for making
  radio-astronomical observations and data
  analysis,
• support of activities to protect
  radio-astronomical observations from harmful
  interference.

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Radio Astronomy Planetary Radar Astronomy
305-m Arecibo Radio Telescope, ?70 cm
70-m Goldstone Radio Telescope ?3.5 cm

(from Campbell et al.)
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Radio Astronomy Planetary Radar Astronomy
Maxwell Montes on Venus Arecibo (Interferometer)

Arecibo Doppler Radar Image of Saturns Rings
(from Campbell et al.)
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URSI Scientific Commissions K.
Electromagnetics in Biology and Medicine

• Physical interactions of electromagnetic fields
  with biological systems
• Biological effects of electromagnetic fields
• Interaction mechanisms
• Human exposure assessment
• Experimental exposure systems
• Medical applications.

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Electromagnetics in Biology and
MedicineTherapeutic Uses of Pulsed
Magnetic-Field Exposure
Pulsed electromagnetic fields with frequencies of
0.1 to a few 100 Hz are successfully used in
medical treatments. These fields are non-ionizing
and do not cause heating of the tissue, rather
they are able to induce significant biological
currents in tissues.

• Some treatments
• Bone formation / fractures
• Cancer (tumour growth)
• Congenital pseudarthrosis
• Depression
• Joint disorders
• Nerve regeneration
• Osteoarthritis
• Pain

(from Thomas et al.)
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Portable Magnetic Field Exposure Unit
Head coils deliver Max 400 µT at outer edge of
head Max 200 µT to the deep brain
dB/dT 400 mT/s - 800 mT/s Gradient 4
mT/m
(from Thomas et al.)
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References
Com. A H.R. Telle, G. Steinmeyer, A.E. Dunlop,
J. Stenger, D.H. Sutter, U. Keller,
Carrier-envelop offset phase control A novel
concept for absolute optical frequency
measurement and ultrashort pulse generation,
Appl. Phys. B 69, 327-332, 1999 Com. B Material
from Richard W. Ziolkowski, Tucson, Arizona, USA
ziolkowski_at_ece.arizona.edu Com. C G. Delisle, K.
Hettak and G. Lucas, Intelligent Antennas for
Future Wireless Communications, in Modern Radio
Science 1999, Ed. M. Stuchly, Oxford Univ. Press,
1999 Com. D C.P.B. Katehi, S.V. Robertson, RF
MEMS and Si-Micromaching in High Frequency
Circuit Application, in The Rev. of Radio
Science 1999-2002, Ed. W.R. Stone, J. Wiley
Sons Inc. Sommerset, NJ, USA, 2002,
p.355-370, Com. E from Handbook of Atmospheric
Electrodynamics, Vol. 1, Ed. H. Volland, CRC
Press, Boca Raton, 1995 Com. F A. Camps, C.T.
Swift, New Techniques in Microwave radiometry for
Earth Remote Sensing Principles and
Applications, in The Rev. of Radio Science
1999-2002, Ed. W.R. Stone, J. Wiley Sons Inc.
Sommerset, NJ, USA, 2002, p.499-518, Com. G
http//iono.jpl.nasa.gov//gim_dailymovie.html
Com. H D.L. Carpenter, Remote Sensing of the
Earth Plasmasphere, Radio Sci. Bull. 308, 13-29,
2004, and the IMAGE web pages http//image.gsfc.n
asa.gov/rpi/, and PPT from J. Burch
http//image.gsfc.nasa.gov/presentation/2001_burch
_gsfc/ Com. J D. B. Campbel, R. S. Hudson, and
J.-L. Margot, Advances in Planetary Radar
Astronomy, in The Rev. of Radio Science
1999-2002, Ed. W.R. Stone, J. Wiley Sons Inc.
Sommerset, NJ, USA, 2002, p.869-899 Com. K
Shupak, N.M., F.S. Prato, A.W. Thomas,
Therapeutic Uses of Pulsed Magnetic-Field
Exposure A Review, Radio Sci. Bull. 307, 9-32,
2003
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If you want to learn more about Modern Radio
Science

join us for URSIs next General Assembly in New
Delhi, India, 23 to 29 October 2005 Vigyan
Bhavan Conference Center