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Radar Siting

Easat specialises in land-based and naval radar, from fixed or mobile sites. Every radar customer has a unique radar requirement which takes into consideration the nature of the site, the radar detection task, and the available budget.

By choosing the most appropriate antenna and transmitter receiver, Easat can put forward the most suitable configuration of radar sensors and associated equipment. Easat engineers have excellent experience in modelling radar performance for a variety of applications.

The radar modelling will usually commence as a desk exercise involving a specified antenna height, and an assumed set of radar, propagation and target parameters.

 Radar Siting (1)

The probability of detection plot as shown above is modelled without taking account of actual terrain features which may affect the radar performance, such as large buildings or hills.

These may cause radar shadows, which can seriously interfere with the radar performance. To evaluate such problems, and to select sites where such shadows are reduced or eliminated, site surveying "on the ground" must always be undertaken.

However, digital terrain modelling may be employed to minimise the time and cost, and sometimes the risks to personnel, of undertaking extensive site surveys in distant and possibly hostile locations. The plot on the right shows the digital map of a coastline, the solid red colour shows the sea surface satisfactorily illuminated by the radar, whilst the in-shore shadows from hills lying between the radar site and the sea are clearly shown (lilac).

Easat will generally undertake, free of charge, the modelling of radar detection from a proposed site which has a known height as an aid to the correct specification of the radar sensor. Physical site surveys, and the combining of radar detection performance with digital terrain modelling, may be chargeable.

 Radar Siting (2)

Site surveys are carried out to assess foundation and tower design, equipment access, power supplies and other services, data and voice communications, buildings and cabins, fire protection, security protection and other necessary requirements.

The applications include the following:

  • Ground-based primary and secondary surveillance radars for civilian airports.
  • Fixed, transportable and mobile primary and secondary air surveillance radars, for defence.
  • Radars for airport surface movement guidance and control; airport surface detection equipment (ASDE).
  • Ground-fixed, ground-mobile, or naval interrogators for Identification Friend or Foe (IFF).
  • Long-range coastal radar for detection of sea surface targets or for detection of both sea and air targets.
  • Surveillance radars for the perimeter protection of sensitive installations or borders.

Selection of the correct radar antenna and location is paramount for the overall system performance and careful consideration for the antenna during the planning stage of a new installation can be critical. To maximise the performance of a VTS or coastal surveillance application there are several important aspects which need to be considered, these are summarised:

  • Position of primary sensor, the radar antenna to provide maximum coverage range. This should be as high as possible to provide the longest detection range and thereby reduce the number of radar antenna required for the planned scheme.
  • Antenna should have as high gain as possible in order to obtain the maximum power on target. In many situations the short pulse length offered by a high gain antenna will reduce the sea clutter return and improve the target range discrimination. Narrow azimuth beamwidth for better separation of targets in close proximity of each other and target resolution.
  • Given that a high antenna location is advantageous for maximum range if the elevation beam pattern is an inverse cosec2 pattern this will greatly assist in the detection of those targets which are closer to the antenna. Therefore, each coastal surveillance project requires evaluation to consider if an individual or customised system solution is necessary.

At Easat we have own engineers who can undertake site visits to assess the local conditions and evaluate the most optimal location to obtain maximum radar coverage and avoid shadow areas.