Active high density multi-element directional antenna system

An active high density multi-element antenna system for radiolocation by identification of the direction of RF radiation from one or more target sources, comprising

• antenna elements configured in multiple concentric rings about a central axis to define arcuate sectors about the central axis,
• the rings having diameter decreasing radially inwardly toward the central axis,
• each of the rings including a plurality of adjacent discrete antenna elements within each sector,
• each of the elements in the concentric rings have mutual relation to radially corresponding elements in at least one other of the concentric rings, such that the radially corresponding elements in the multiple rings define respective antenna units which are radial to the central axis,
• each of the antenna units being selectively operatively enabled or selectively operatively disabled in rotational sequence about the central axis to provide signal selectivity in a narrow beam width defined by the respective antenna units and whereby the selectivity is rotatable about the central axis,
• means for electrically isolating each of the antenna units from adjacent antenna units,
• feedpoints for each of the antenna units for receiving received RF signals from the respective antenna units when enabled,
• an array control system for causing RF scanning of the antenna units about the central axis within a least a selected one of the sectors, the array means being operable for identifying which antenna unit within the selected sector is representative of an azimuth representing the direction to the target source,
• wherein the array control system scans for a target transmitter source by scanning within preselected sectors in amplitude-determining mode, by sector-by-sector scanning of relative amplitude evaluation, a received signal within any one of the preselected sectors, to identify a maximum signal sector, and then converts to a second mode for identifying which of the antenna units within the maximum signal sector is representative of an azimuth representing the direction to the target source.

A method of scanning and radiolocation of one or more target sources of RF radiation comprising:

• providing a high density multi-element antenna system having antenna elements configured in multiple concentric rings about a central axis to define arcuate sectors about the central axis, wherein the rings having diameter decreasing radially inwardly toward the central axis, the rings including a plurality of adjacent discrete antenna elements within each sector, and each of the elements in the concentric rings have mutual relation to radially corresponding elements in at least one other of the concentric rings, such that radially corresponding elements in the multiple rings define respective antenna units which are radial to the central axis, and an array control system therefor, operating the control system to provide at least:
• first mode scanning of the antenna units about the central axis in a received RF amplitude sensing mode within a least a selected one or more of the sectors selectively operatively enabling or selectively operatively disabling the antenna units in rotational sequence about the central axis to provide signal selectivity in a narrow beam width defined by the respective antenna units and whereby the selectivity is rotatable about the central axis, and
• second mode scanning of the antenna units about the central axis in a received RF phase sensing mode within a least a selected one or more of the sectors operating the control system to provide identification of which antenna unit within the selected sector is most closely representative of an azimuth representing the direction to the target source.