Abstract: A transmit-receive module has a battery energy store with associated circuitry for generating power (RF power) over periods ranging, as desired, from periods as short as small fractions of one second to continuous emissions over prolonged periods. The arrangement bears a definite cost advantage over known arrangements and retains utility for various applications, radar and space-based applications for example.

Abstract: Faraday Rotation causes rotation of the plane of polarization of plane polarised radiation emitted by a radar e.g. a synthetic aperture radar and, if returns polarized in orthogonal planes are measured at the synthetic aperture radar in order to determine polarimetric characteristics of the ground, which could show up features of the ground such as crop patterns, the measurements made at the SAR are contaminated by the Faraday Rotation. In the invention, the transmitted plane polarized beam is pre-rotated in transmitter 9, the radar returns in receiver 13 are mathematically adjusted in signal formatting 14, 15 to compensate for just the pre-rotated angle, to produce data streams on downlink 16 uncontaminated by the Faraday Rotation.