As part of ESA’s continuing efforts to develop new and better instruments for observing Earth, the Agency has initiated a series of studies to assess the feasibility of using a very short radar wavelength – only 8.5 mm – called Ka-band.

In recent years, Ka-band synthetic aperture radar (SAR) interferometry from airborne platforms has shown good performance levels and potential for using over a wide range of targets. The indications are that this short wavelength radar would be able to offer both very high-resolution images and precise measurements of surface height that would be suitable for a wide range of environmental applications.

To support feasibility studies for a spaceborne high-resolution single-satellite interferometric SAR system operating in Ka-band and the associated technology roadmap, a better knowledge of Ka-band backscatter levels of natural targets as a function of incidence angles is required. The assessment of Ka-band single-pass interferometry for the different envisaged remote-sensing applications is also essential to consolidate instrument parameterisation and requirements.

The KaSAR campaign addresses critical needs related to the studies, which are currently lacking in proper datasets supported with in situ characterisation. In particular, the focus is on a better definition of instrument sensitivity, dynamic range and instrument modes including polarisation.

The campaign started last June 2012 in southern France deploying the Onera airborne Drive system on the Busard platform over selected test sites and use of archive Ka-band datasets acquired with the Ramses system in 2008 over the same sites.

Objectives

• Radiometry of Ka-band over natural medium reflectivity surfaces (i.e. bare soil, forest, grass/agriculture fields) as a function of incidence angles from 20° to 50°.
• Dynamic range of Ka-band signal (radar cross-sections) over targets of very high (anthropogenic bright targets), medium (bare soil, vegetation) and low (flat inner waters or runways) reflectivity.
• Signature variability as a function of time-varying environmental conditions over selected land (wet and dry) and water (flat and rough) surfaces.
• Variability and information content of Ka-band at different polarisations.
• Ka-band signature over hard targets (ships, vehicles) and infrastructure targets (pipelines, power lines, train tracks, etc.) for size, shape and structural target characterisation.