Compact microwave and millimeter wave radars operating at 77 GHz and having resolution of no less than 3.2 meters at a distance of 100 meters. The exemplary dimensions of the radars are 145 millimeters in diameter and 100 or 85 millimeters long. The antenna of the radars employs folded optic design, with the actual focal length of the radar being less than that of the lens in the antenna alone.

Compact microwave and millimeter wave radar

A master station master antenna having a high directivity in an upper direction, a slave station and a slave antenna having a high directivity in the high direction are arranged on a floor of a room, and furniture is arranged on the floor between the master antenna and the slave antenna. Also, a master reflecting mirror is arranged on a ceiling of the room placed just above the master antenna, and a slave reflecting mirror is arranged on the ceiling placed just above the slave antenna. When an electric wave having a data signal is radiated from the master station, the electric wave radiated in the upper direction passes through a first transmission route and is reflected by the master reflecting mirror toward a horizontal direction. Thereafter, the electric wave passes through a second transmission route near the ceiling and is again reflected by the slave reflecting mirror toward the lower direction. Thereafter, the electric wave passes through a third transmission route and is received by the slave antenna because the slave antenna has a high directivity to receive the electric wave transmitted from the upper direction. Therefore, the data signal can be reliably detected by the slave station without being interrupted by the furniture.

Indoor radio communication system

A multi-spectral imaging apparatus with a common collecting aperture, which combines a high performance infrared imaging system with a high performance millimeter wave transceiving system. Two mirror surfaces are combined with a refractive corrector in the infrared mode and with a single reflective parabolic antenna in the millimeter wave mode. The dual mode system functions well in a scanning as well as a staring configuration.

Multi-spectral imaging system

A feedhorn driving method and apparatus allows the establishment of multiple phase centers using only a single multimode feedhorn. At least two higher-order modes are extracted from the feedhorn and weighted in amplitude and phase. The phase center separation is established in accordance with an assigned weights. The feedhorn has application in i.a. moving target indication systems.

Multiple phase center feedhorn for reflector antenna

A low-profile antenna system includes a main reflector (102) formed as a shaped main reflector surface that is approximately, but not precisely, parabolic. The main reflector (102) has a main reflector edge configuration (103) that is asymmetric. A feed system (104) for the main reflector includes a subreflector (106) formed as a shaped subreflector surface that is approximately, but not precisely, elliptical. The subreflector has a subreflector edge configuration (107) that is also asymmetric. An RF feed horn (108) associated with the feed system 104 has an aperture profile which also has an asymmetric shape.

Antenna with Shaped Asymmetric Main Reflector and Subreflector with Asymmetric Waveguide Feed

A two-band multimode microwave source for an antenna of a low-elevation-tracking radar comprises a higher-frequency section nested in a lower-frequency section, the two sections having E-planes perpendicular to each other. The lower-frequency section includes two outer pairs of waveguides separated by a block which convergingly projects beyond their output ends and is bisected by the E-plane of that section. The higher-frequency section includes two inner pairs of waveguides disposed within that block and separated by an obstruction lying in the last-mentioned E-plane. The higher-frequency wave emitted by the inner waveguides is made planar by a lens disposed at n output aperture of the structure which is transparent to the lower-frequency wave. In a Cassegrain-type radar antenna the lower-frequency wave emitted by the source is returned by a semitransparent intermediate reflector toward a main reflector provided with a grid which rotates its plane of polarization to let it pass out through the intermediate reflector along with the higher-frequency wave which, passing unattenuated through the intermediate reflector, is returned by a solid outlying reflector to the main reflector.

Two-band microwave antenna with nested horns for feeding a sub and main reflector

An antenna having two crossed cylindro-parabolic reflectors in which the generatrices of said reflectors are orthogonal. The source is placed close to the center of the main reflector, which is further provided with polarization rotation means. The auxiliary reflector is placed facing the main reflector and it is such that it is transparent to a wave polarized linearly in one direction and reflecting to the waves polarized in an orthogonal direction.

Antenna having two crossed cylindro-parabolic reflectors

A radar antenna of the Cassegrain type comprises a paraboloidal principal reflector confronting a hyperboloidal or flat auxiliary reflector of smaller radius directing linearly polarized radiation from a source on their common axis toward the principal reflector along lines passing through the focal point thereof to produce an axially extending outgoing beam whose central part is intercepted by the auxiliary reflector The latter consists of an array of linear conductors generally parallel to the direction of polarization while the principal reflector is formed by another conductor array generally inclined at 45° to that direction, the latter array being backed by a solid mirror separated therefrom by a distance smaller than a quarter wavelength at the midfrequency of the emitted radiation The composite wave leaving the principal reflector has an elliptical polarization which it retains in an annular portion of the outgoing beam bypassing the auxiliary reflector; only a linearly polarized component of that wave rotated through 90° from the original direction of polarization, however, passes the array of the auxiliary reflector in the central beam portion intercepted thereby

Radar antenna with rotating linear polarization designed to reduce jamming

A reflector with parallel strips is constructed by stacking and gluing plates (p1, p2, p3...) made from a dielectric material, these plates which are covered on one of their faces with a metallic deposit (m), being disposed such that the non-metallised face of one plate is against the metallised face of the neighbouring plate, this assembly forming a compact unit (B) in which the reflector is machined. Application: construction of selective reflectors with parallel strips or polarisation-rotating reflectors used in the antennas of radar systems.

Microwave reflector with parallel strips and method of manufacturing such a reflector

A microwave reflector having metallic surfaces and nonmetallic surfaces is perfectly reflecting for the waves of a first polarization and partly transparent for the waves of a second polarization orthogonal to the first. The reflector is primarily applicable to radar systems.

Jean Bouko

Papers

Two-band microwave antenna with nested horns for feeding a sub and main reflector

Antenna having two crossed cylindro-parabolic reflectors

Radar antenna with rotating linear polarization designed to reduce jamming

Microwave reflector with parallel strips and method of manufacturing such a reflector

Device for reflecting the electromagnetic waves of a polarization and a method of construction of said device