The Secretary of State for Defence in Her Britannic Majesty's Government

Paul M Backhouse

Huw D Rees

Christopher J Alder

Norman Apsley

A radiation sensor for the microwave and millimeter-wave regions incorporates a lens having two parallel focal planes, these being defined by a polarization-selective reflector grid within the lens. One focal plane is occupied by a receive array of crossed dipole antennas with respective mixer diodes. One dipole of each antenna couples to a local oscillator signal and the other couples to a receive signal reflected by the grid. These signals are mixed by the diodes to produce intermediate frequency signals for subsequent processing. The other focal plane is occupied by a transmit array of separately activatable polarization switching antennas arranged to define a range of transmit beam directions. This focal plane may alternatively be occupied by a second receive array.

Radiation sensor

An antenna device comprises a dielectric sheet substrate having an antenna patch on one surface and a ground plane on the other surface. A hemispherical dielectric lens is arranged over the antenna patch in intimate contact with it. The substrate and the lens are of low and high permittivity material respectively. The lens couples the antenna patch radiation away from the substrate. This avoids the inefficiency arising from power trapping in the substrate of a prior art microstrip patch antenna. The antenna device radiates into a comparatively narrow cone axially perpendicular to the antenna patch, and coupling of radiation from a power source to free space can theoretically be 100%. The antenna impedance is a function of its structural geometry, and is easily designed for impedance matching to a power source.

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Worcs, United Kingdom

Paul M Backhouse