A radar system for air volume surveillance, the radar having a transmitter and receiver with separate antennas. The receiver aperture being relatively large compared with the transmitter aperture such that the receiving beam is narrower than the transmitting beam, which itself is relatively small compared with the volume to be surveyed. Multiple receiving beams can be configured so that collectively they substantially match the angular volume of the transmitting beam; and in which the transmitter is arranged, when operating, to transmit a signal with a duty cycle greater than fifty percent.

A system and a method are provided for achieving long range, over the horizon (OTH), persistent surveillance, alerting, tracking and situational awareness against small, low radar cross section moving targets. The system and method use one or more tethered unmanned arial systems, or unmanned arial vehicles, to lift components including a radar antenna to a height above nearby obstacles or much higher. The system and method can also be used for subsurface radar detection and tracking applications, as well as communications with submarines.

A system, computer program product and method of examining the ionosphere is disclosed. The method includes capturing, at one or more antennas, radio frequency (RF) emissions preceding a broadband emission event. The RF emissions are then recorded at one or more broadband receivers over a period of time. A first tuning of the received RF emissions is selected to detect ionospheric reflections, and a second tuning of the received RF emissions is selected to detect direct line of sight emissions. From the selected tunings, an amplitude or complex time series of the second tuning with one or more channels of the first tuning are correlated to calculate a relative virtual echo height of the ionosphere.

An unmanned, autonomous, self-sustaining and self-repairable floating platform which is positioned at a fixed location within the sea, capable of constantly monitoring, without having to be removed, a specific maritime zone including a sea surface area and the aerial and underwater space pertaining to this sea surface area, the platform comprising telecommunication means adapted to exchange surveillance related information with a Command, Communication and Control center. The platform comprises a deck maintained well above sea surface through a connecting member with an underlying, fully or partially submerged, system of floaters and is equipped with a variety of sensors and surveillance systems such as radar, Li-dar, sonar, electromagnetic, unmanned vehicles (UAVs, UUVs and USVs), active and passive self-protection systems as well as research and rescue equipment. A mast having a substantial height (usually 40-50 m) and equipped with appropriate surveillance devices is mounted and ex-tends vertically upwardly the deck.

Disclosed is a method of mitigating the effects of anomalous propagation in a Radar system, comprising the steps of: receiving a plurality of returns from a plurality of transmit pulses; calculating a difference in magnitude between each of the plurality of returns and its successor; if one of the calculated differences indicates a first step change greater than a first predetermined threshold, calculating a first average magnitude of the returns received after the first step change, and replacing the returns received before the first step change with synthesised returns having a magnitude equal to the first calculated average magnitude.

System and methods for implementing a vector sensor array surface wave radar is provided. In one or more examples, the system can include a vector sensor array antenna that includes electromagnetic elements collectively configured to receive surface wave reflections generated by radar transmit antenna waves reflecting back from targets of interest. Once received by the vector sensor array, in one or more examples, the system can further include components that can process the incoming signal and use the incoming single to determine the location of one or more targets. In one or more examples, the vector surface array antenna can include three separate loop antennas that are arranged orthogonally to one another, and three dipole antennas that are arranged orthogonally to one another. In one or more examples, the vector surface array antenna can be configured to receive signals in the high frequency (HF) band.

A radar system for air volume surveillance, the radar having a transmitter and receiver with separate antennas. The receiver aperture being relatively large compared with the transmitter aperture such that the receiving beam is narrower than the transmitting beam, which itself is relatively small compared with the volume to be surveyed. Multiple receiving beams can be configured so that collectively they substantially match the angular volume of the transmitting beam; and in which the transmitter is arranged, when operating, to transmit a signal with a duty cycle greater than fifty percent.

A system and a method are provided for achieving long range, over the horizon (OTH), persistent surveillance, alerting, tracking and situational awareness against small, low radar cross section moving targets. The system and method use one or more tethered unmanned arial systems, or unmanned arial vehicles, to lift components including a radar antenna to a height above nearby obstacles or much higher. The system and method can also be used for subsurface radar detection and tracking applications, as well as communications with submarines.

System and methods for implementing a vector sensor array surface wave radar is provided. In one or more examples, the system can include a vector sensor array antenna that includes electromagnetic elements collectively configured to receive surface wave reflections generated by radar transmit antenna waves reflecting back from targets of interest. Once received by the vector sensor array, in one or more examples, the system can further include components that can process the incoming signal and use the incoming single to determine the location of one or more targets. In one or more examples, the vector surface array antenna can include three separate loop antennas that are arranged orthogonally to one another, and three dipole antennas that are arranged orthogonally to one another. In one or more examples, the vector surface array antenna can be configured to receive signals in the high frequency (HF) band.

This beam formation device includes: a Doppler bin detection unit that detects a target Doppler bin which is a Doppler bin in which a target signal is present, from a correlation matrix calculated by a correlation matrix calculation unit and a reception signal vector calculated by a Doppler analysis unit; a target signal removal unit that removes, from the correlation matrix calculated by the correlation matrix calculation unit, the target signal in the target Doppler bin detected by the Doppler bin detection unit and thereby calculates a target-signal-removed correlation matrix from which the target signal has been removed; and a weighting calculation unit that calculates an adaptive weighting of the reception signal vector from the target-signal-removed correlation matrix calculated by the target signal removal unit. A beam formation unit forms an adaptive beam from the reception signal vector calculated by the Doppler analysis unit and the adaptive weighting calculated by the weighting calculation unit.