New Radar Technology 8 500-10 500 MHz Band

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New Radar Technology8 500-10 500 MHz Band

• Presented by

Mr. Frank Sanders National Telecommunications
Information Administration
Mr. Thomas Fagan Raytheon
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Technical Characteristics

• 8 500-10 500 MHz radars exist on land-based,
  transportable, shipboard, and airborne platforms.
• Radiodetermination functions include airborne,
  space surface search, ground-mapping,
  terrain-following, navigation (both aeronautical
  and maritime), and target-identification.
• Major differences among radar designs include
  transmitter output devices, transmit duty cycles,
  emission bandwidths, presence and types of
  intra-pulse modulation, frequency-agile
  capabilities of some, transmitter peak and
  average powers, and types of transmitter RF power
  devices.
• These characteristics, individually and in
  combination, all have major bearing on the
  compatibility of the radars with other radio
  systems in their environment.

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More Technical Characteristics

• Many radiolocation radars in this band are
  primarily used for detection of airborne objects.
• The purpose is to measure target altitude as
  well as range and bearing.
• Some of the airborne targets are small and at
  long ranges as great as 555 km (300 nautical
  miles).
• These radiolocation radars must have high
  sensitivity and must provide a high degree of
  suppression to all forms of clutter return,
  including that from sea, land, and precipitation.
• In some cases, the radar emissions in this band
  are required to trigger radar beacons.

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Mission Requirements Dictate General Design
Characteristics

• Basic radar design parameters are as follows
• Minimum target size (cross section) and maximum
  range requirements
• Maximum available space for antenna
  (constrained, for ex., by platform size)
• Spectrum band (driven by propagation needs
  maximum possible antenna size)
• Required (minimum acceptable) signal-to-noise
  ratio (SNR) for target echoes
• Minimum number of pulses (N), echoed from each
  target to achieve minimum SNR
• Antenna scan rate and beam scanning pattern,
  determined by the values of N and PRI
• Pulse repetition interval (PRI), determined by
  maximum radar range
• Pulse width and shape, determined by need for
  best possible location resolution

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Mission Requirements Dictate General Design
Characteristics (cont.)

• Basic radar design parameters continued
• Pulse peak power, determined by target size
  (cross section) and maximum range
• Pulse modulation (coding), which can allow
  pulses to be transmitted at lower peak power, but
  with proportionately longer length. (i.e.,
  average power tends to stay constant).
• Selection of radar transmitter output device is
  determined by needs for peak power, pulse
  modulation (if any), size, weight, cost,
  reliability, and spectrum characteristics.
• 8 500-10 500 MHz radars often have small
  platform-size (and thus small antenna)
  constraints.
• 8 500-10 500 MHz radars often need to observe
  small targets at relatively long ranges using
  designs that have reasonable cost, reliability,
  and maintainability.
• These constraints feed back into all of the
  design parameters listed on the previous slide.

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Mission Requirements Dictate General Design
Characteristics (cont.)

• 8 500 10 500 MHz radars often need high
  transmitter peak and average power
• Master-oscillator-power-amplifier transmitters
  may be preferred over power oscillators.
• Tunability and frequency-agility are sometimes
  required
• Some require pulse modulation such as a linear
  (or non-linear) FM chirp or phase codes.
• Antenna mainbeams often need to be steerable in
  one or both angular dimensions, sometimes using
  electronic beam steering.

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Mission Requirements Dictate General Design
Characteristics (cont.)

• Driven by mission requirements, individual 8
  500-10 500 MHz radars need a wide variety of
  pulse widths pulse repetition frequencies.
  Chirp radars need a variety of chirp bandwidths.
  Some frequency-agile radars need a variety of
  agile-frequency modes. Such design flexibilities
  can provide useful tools for performing missions
  while maintaining compatibility with other
  radars in the environment.
• Versatile receiving and processing capabilities
  are also often needed for
• 8 500-10 500 MHz radars to include
• Auxiliary sidelobe-blanking receive antennas
• Processing of coherent-carrier pulse trains to
  suppress clutter return by means of
  moving-target-indication (MTI)
• Constant-false-alarm-rate (CFAR) techniques
• Adaptive selection of operating frequencies
  based on sensing of interference on various
  frequencies (some cases).

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Marine RadarU.S. Department of Commerce

• Typical X-Band maritime radionavigation radar
• Magnetron Output
• Integrated Platform (receiver transmitter
  contained in small mast- mounted package)
• Typically found onboard pleasure craft and
  commercial ships

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8 500-10 500 MHz Marine Radar
Mk-2 Pathfinder (marine)
Raytheon
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Mission Requirements Dictate Frequency Range

• Atmospheric attenuation and water vapor
  absorption help determine radar operational
  frequencies.
• Weather radars use frequencies where water vapor
  absorption is high.
• Radiolocation radars use frequencies where water
  vapor absorption is low.
• Only certain frequency bands have low water vapor
  absorption.

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8 500-10 500 MHz RadarDesign Tradeoffs

• Except for some ground-based systems, 8 500-10
  500 MHz platform dimensions typically restrict
  the maximum possible size of transmitter
  antennae, both for present and future systems.
• Small antenna sizes tend to force high pulse
  peak power levels for adequate target detection.
  Alternatively, if lower peak power levels are
  used then longer pulse widths are required to
  expose targets to enough total energy to detect
  them.
• But, if longer pulses are used, then additional
  pulse modulation (coding) is required to achieve
  adequate range resolution.

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8 500-10 500 MHz RadarDesign Tradeoffs (cont.)

• The choice of 8 500-10 500 MHz transmitter
  output device technology is a major design
  decision. It significantly affects radar
  performance, cost, and spectrum out-of-band and
  spurious emission levels. Tradeoffs between all
  these parameters must be carefully balanced by
  designers of X-band radars.
• Some 8 500-10 500 MHz radar designs may be
  driven primarily by cost and size factors, and
  may therefore need to use cheaper and lighter
  tubes, such as magnetrons. Conversely, more
  advanced transmitter output devices (eg solid
  state), may be more costly, heavier, and more
  complex. But they may offer better-controlled
  pulse shaping and thus possibly improved spectrum
  out-of-band and spurious emission characteristics.

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8 500-10 500 MHz Airborne Radar

• Typical example of an Airborne Radar where it
  must fit into the nosecone of an aircraft
• Note that the antenna is small to fit into the
  limited amount of space available

AN/APG-73 radar
Raytheon
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8 500-10 500 MHz Airborne Radar
AN/APG-70 radar
Raytheon
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8 500-10 500 MHz Surface Surveillance Radar
Used for monitoring ground traffic (airplanes,
service vehicles, baggage vehicles, security
vehicles) at airports
Advanced Surface Movement Radar (ASMR)
Raytheon
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Future 8 500-10 500 MHz Radar Design Trends
(cont.)

• More flexibility will be needed, including the
  capacity to operate different modes in different
  azimuth and elevation sectors.
• Capability to operate in a wide bandwidth will
  be needed.
• Electronically-steerable antennae will become
  more common.
• Current technology makes phase steering a
  practical and attractive alternative to frequency
  steering.
• Radars in other bands have employed phase
  steering in both azimuth and elevation, and can
  steer any fundamental frequency in the radars
  operating band to any arbitrary azimuth and
  elevation within its angular coverage area.
• Phase steering may enhance electromagnetic
  compatibility in many circumstances.
• Reduction of unwanted emissions below those of
  the existing radars that employ magnetrons or
  crossed-field amplifiers may occur through the
  use of linear beam and solid-state output devices.

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Future 8 500-10 500 MHz Radar Design Trends
(cont.)

• Radar designs will continue to evolve
• Towards solid-state output devices
• Radar bandwidth will increase (instantaneous and
  operational)
• Peak power will increase on some radars
• Average power will increase on some radars
• Pulse Repetition Frequency (PRF) and pulse width
  will increase
• Amount of coding modulation (phase and chirp)
  will increase due to the trend towards
  solid-state output devices
• Use of this radar frequency band will increase.

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Summary

• Development of radars in this band is an ongoing
  process that continue to evolve as technology
  advances.
• Working Party 8B will continue to follow these
  technology trends and their consequences and
  impact on the use of the radio spectrum.
• Thank You for your attention!