A radar lens 14 is made from a conventional Fresnel lens 10, but replaces the conventional curved surface 32 with a stepped approximation thereto 22, 24, 26, preferably of three steps. The thickness of the stepped lens 14, at each step, is a half-wavelength or a multiple half-wavelength of the radar operating frequency in the medium of the lens 14. The half-wavelength or multiple half-wavelength separation of the steps 22, 24, 26 causes reflections from the front 16 and rear 18 surfaces to cancel, thereby minimizing the (undesirable) standing wave between the lens 14 and the feed horn or feed horns 46, 48, 50. This avoids the necessity of reducing the standing wave by presenting the curved or stepped side 18 forward. The planar side 16 of the lens 14 (unlike the stepped side 18) doesn't need to be protected from road debris. The lens 14 can therefore be molded as an integral unit of a radome, desirable in the automotive setting. This lens 14 is also thin enough (and, therefore, light enough) that it can be moved side-to-side very rapidly, preferably by a combination of cams 42, 52 and springs 44, 54. This allows a very fast scan, albeit over a limited field of view. Gimballing 56 the lens 14 and feed horns 46, 48, 50 together provides a slower scan, but gives an unlimited field of regard. Combining the two gives a fast scan and unlimited field of regard, desirable in the missile setting.

Fresnel zone lens antenna

Durable, lightweight, radar lens antenna

A millimeter wave radar-equipped headlamp includes a millimeter wave radar that detects an object ahead of a vehicle, and a lighting device unit that irradiates an area ahead of the vehicle. The lighting device unit incorporates an antenna module of the millimeter wave radar. The lighting device unit includes a projection lens, a light source, a reflector, and a shade. The antenna module includes a millimeter wave waveguide, and a millimeter wave reflection mirror. A reflection surface of the millimeter wave reflection mirror is formed by a spheroidal surface having a first focal point located in the vicinity of the opening of the millimeter wave waveguide, and a second focal point located forward of the rear focal point.

Millimeter wave radar-equipped headlamp

The invention relates to a microwave antenna for the generation of a beam with adjustable parameters. Use is made of a reflective Fresnel zone plate that is written into a thin layer of silicon by means of a laser plus deflection means. A reflector is positioned behind the Fresnel zone plate for reflecting microwave radiation that is not reflected by the Fresnel zone plate.

Fresnel zone lens antenna

Citations

Durable, lightweight, radar lens antenna

Millimeter wave radar-equipped headlamp

Adjustable microwave antenna

References

Frequency selective mesh with controllable mesh tuning

Zone plate radio transmission system

Radio-frequency device

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