A vehicle warning sign comprises: a reflective material for at least visible light; and at least one of (i) a heating element for detection by a thermal sensor or (ii) a corner reflector for detection by a radar, the corner reflector oriented substantially in a common direction with the reflective material.

Disclosed is a helmet provided with a radar reflector. The helmet includes a helmet body formed in a shape corresponding to a shape of a user head, and the radar reflector mounted on an outer surface of the helmet body to reflect a radar signal transmitted from radar equipment. The radar reflector includes a plurality of reflection units each concaved in a trigonal pyramid shape having one opened surface, each of the plurality of reflection units reflecting the radar signal. Thus, by applying the radar reflector to the helmet of a user aboard an object to be detected by using a radar signal, the radar signal is effectively reflected in bad weather or at night, thereby improving the recognition rate of radar equipment.

An electromagnetic-radiation-reflecting structure that is attached at a location on a user's body. The electromagnetic-radiation-reflecting structure generating, as the user proceeds in usual fashion, a micro-Doppler effect as a result of its attachment at the location on the body so that a radar cross section of the user is increased, a material of the electromagnetic-radiation-reflecting structure having a conductivity greater than 100 S/m or a conductivity less than 100 S/m, a relative permeability between 100 and 10.sup.5, and a relative permittivity between 1 and 14; or has a conductivity less than 100 S/m, a relative permeability between 1 and 100, and a relative permittivity between 7 and 14; and a surface area of the electromagnetic-radiation-reflecting structure (120) is greater than 1000 mm.sup.2.

A data processing system for navigation using-spread spectrum signals herein implements causing a transceiver of the data processing system to transmit a first electromagnetic signal; receiving, via the transceiver, second electromagnetic signals associated with a first object responsive to the first electromagnetic signal, the second electromagnetic signals including first spread-spectrum signals and an identification of the first object incorporated into the first spread-spectrum signals, each respective second electromagnetic signal of the second electromagnetic signals being transmitted from a separate location on the first object; analyzing the second electromagnetic signals to obtain the identification of the first object; and determining a first estimated location of the data processing system relative to the first object by calculating a difference between the time of transmission of the first electromagnetic signal and a respective time of receipt of each of the second electromagnetic signals.

An absorber device for electromagnetic sensor systems has at least one aperture. Each aperture is able to be opened and closed by an aperture closure. The absorber device is designed in such a way that when the aperture is open, electromagnetic waves incoming through the aperture do not then leave the absorber device, and when the aperture is closed, electromagnetic waves impinging on the aperture are reflected.

The invention describes a method for reducing interference effects in a radar system, which has at least two transceiver units (S1, S2), which are in particular spatially separated from one another, wherein the method comprises the following steps: —a transmission step (VS1), in which a first transmission signal (sigTX1) of the first transceiver unit (S1) is sent and received to and by a second transceiver unit (S2) and a second transmission signal (sigTX2) of the second transceiver unit (S2) is sent and received to and by the first transceiver unit (S1) via a radio channel (T), wherein the transmission signals (sigTX1, sigTX2) are modulated according to an orthogonal frequency multiplex method; and—a pre-correction step (VS2), in which correction values (γ1, γn, γ2) are determined from the received transmission signals (sigTX1, sigTX2) and in particular are exchanged between the transceiver stations (S1, S2), wherein the received transmission signals (sigRX1, sigRX2) are postprocessed on the basis of the correction values (γ1, γn, γ2), so that influences of interference variables, in particular of phase noise and/or a time offset and/or unknown initial phase positions, are reduced.

A testing device for testing a distance sensor that operates using electromagnetic waves includes: a receiving element for receiving an electromagnetic free-space wave as a receive signal (S.sub.RX); and a radiating element for radiating an electromagnetic output signal (S.sub.TX). In a test mode, a test signal unit generates a test signal (S.sub.test), and the radiating element is configured to radiate the test signal (S.sub.test) or a test signal (S′.sub.test) derived from the test signal (S.sub.test) as the electromagnetic output signal (S.sub.TX). In the test mode, an analysis unit is configured to analyze the receive signal (S.sub.RX) or the derived receive signal (S′.sub.RX) in terms of its phase angle (Phi) and/or amplitude (A) and store a determined value of phase angle (Phi) and/or amplitude (A) synchronously with the radiation of the test signal (S.sub.test) or of the derived test signal (S′.sub.test) as the electromagnetic output signal (S.sub.TX).

Systems and methods for mapping location and characteristics about traffic participants are described. The systems and methods advantageously use correlative receivers for observing wireless emissions from or reflected by a plurality of traffic participants to allow for tracking geolocation and velocimetry information in real-time. The real-time geolocation and velocimetry information can be useful in autonomous vehicle navigation applications and useful for reducing computational burdens associated with tracking locations of many multiple traffic participants using direct sensor measurements, for example.

An aspect of the present disclosure is directed to and provides radar-reflecting systems and apparatus that employ metasurfaces to produce enhanced radar cross sections that are greater than those produced by the geometry of the surfaces alone. Another aspect of the present disclosure is directed to and provides heat-ducting systems and apparatus that include metasurfaces. A further aspect of the present disclosure is directed to and provides cards with metasurfaces. Exemplary embodiments utilize fractal plasmonic surfaces for a metasurface.

A non-contact object and/or gesture detection system includes at least one sensor configured to sense an object or motion within a field of view (FOV) using radio frequency radiation. Various sensor and brackets are provided which may allow a position and/or tilt of the sensor to be adjusted for controlling the FOV. A sensor housing includes a vent filter that breathable but impermeable to liquids. Various antenna designs are provided to provide desired FOV sizes and shapes, particularly for optimizing a radiation pattern that is relatively wide and shallow. A steerable antenna layout is also provided for controlling the location of the FOV without an adjustable bracket. A sensor housing including a projector mount for an icon projector is provided. A seal prevents debris from entering between the antenna and the bumper.