Abstract: A radar surveillance system is described in which the radar beam re-visits each area of interest after a short period of time, by electronically reconfiguring a scanned beam to an offset position for an interleaved sub-dwell, within a scan period. This ‘look-back’ capability, where the area under test is re-visited after approximately 1 second, allows the natural de-correlation of sea clutter to take place between the initial and look-back samples of the surveillance area. The re-visit time can be adjusted to best exploit the de-correlation characteristics of the sea clutter return.

Abstract: A radar surveillance system is described in which the radar beam re-visits each area of interest after a short period of time, by electronically reconfiguring a scanned beam to an offset position for an interleaved sub-dwell, within a scan period. This ‘look-back’ capability, where the area under test is re-visited after approximately 1 second, allows the natural de-correlation of sea clutter to take place between the initial and look-back samples of the surveillance area. The re-visit time can be adjusted to best exploit the de-correlation characteristics of the sea clutter return.

Abstract: This invention relates to reducing the complexity and cost of antenna arrays and is more specifically concerned with reducing the complexity of an antenna apparatus (10). It provides an antenna array (62) made up of a vertical stack of horizontal linear structures (74) each having several groups of neighboring array antenna elements (78), the groups (74) having variable numbers of the antenna elements (78) each connected to a transmit/receive module (66). The advantage of this configuration is that less communication modules (66), such as transmit/receive modules, are required to operate the antenna array (62), reducing the weight, power consumption and cost of an antenna apparatus (10) incorporating such an antenna array (62) without significantly limiting the capability and/or performance of a system compared to a conventional solution.