Plextek Limited

Graham Pearson

David Spreadbury

Steve Greendale

A scanning radar system suitable for detecting and monitoring ground-based targets includes a frequency generator, a frequency scanning antenna, and a receiver arranged to process signals received from a target so as to identify a Doppler frequency associated with the target. The frequency generator generates sets of signals, each set having a different characteristic frequency, and includes a digital synthesiser arranged to modulate a continuous wave signal of a given characteristic frequency by a sequence of modulation patterns to generate one set of signals. The frequency scanning antenna cooperates with the frequency generator to transceive radiation over a region having an angular extent dependent on the generated frequencies. Digital synthesiser techniques capable of precise frequency generation and control are combined with passive frequency scanning and Doppler processing techniques, enabling accurate control of range and scan rates, and optimisation of range cell size for factors such as slow and fast target detection and Signal to Noise ratio, so that targets can be detected at distances considerably farther away than is possible with known systems having similar power requirements.

Radar system

Embodiments of the invention are concerned with frequency scanning antennas for transceiving radio frequency energy for use in detecting and monitoring ground-based targets. In one arrangement the frequency scanning antenna is embodied as a structure that is capable of steering a radio frequency beam to a plurality of different angles about the antenna structure: the antenna structure comprises at least two array antennas and a controller for controlling input of energy to the two array antennas, and the array antennas are disposed within the antenna structure such that the antenna structure is capable of steering a beam to a first angle using one of said two array antennas and of steering a beam to a second angle, different to said first angle, using the other of said two array antennas. Thus in embodiments of the invention two or more array antennas are arranged to form an antenna structure, and the feed to a respective antenna array of the antenna structure is coordinated so that individual scan areas can be combined to generate an increased overall scan region.

Frequency scanning antenna

Embodiments of the invention are concerned with a radar system, and relates specifically to scanning radar systems that are suitable for detecting and monitoring ground-based targets. In one aspect, the radar system is embodied as a scanning radar system comprising a frequency generator, a frequency scanning antenna, and a receiver arranged to process signals received from a target so as to identify a Doppler frequency associated with the target, wherein the frequency generator is arranged to generate a plurality of sets of signals, each set having a different characteristic frequency, the frequency generator comprising a digital synthesiser arranged to modulate a continuous wave signal of a given characteristic frequency by a sequence of modulation of patterns whereby to generate a said set of signals, and wherein the frequency scanning antenna is arranged to cooperate with the frequency generator so as to transceive radiation over a region having an angular extent dependent on the said generated frequencies. Embodiments of the invention thus combine digital synthesiser techniques, which are capable of precise frequency generation and control, with passive frequency scanning and Doppler processing techniques. This enables accurate control of range and of scan rates, and enables optimisation of range cell size for factors such as slow and fast target detection and Signal to Noise ratio, and thus enables detection of targets located at distances considerably farther away than is possible with known systems having similar power requirements.

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Essex, United Kingdom

Graham Pearson