The invention relates to a method for estimating the direction of arrival of an electromagnetic wave at an antenna array (2), comprising the steps of: estimating (202) a covariance matrix of signals acquired by the antenna array (2); calculating (204) a normalised eigenvector of the covariance matrix; correlating (205) the normalised eigenvector with a first reference table and a second reference table so as to produce a first correlation spectrum and a second correlation spectrum comprising correlation indices associated, respectively, with different directions of arrival; constructing (312) a third reference table by linear combination of the first reference table and the second reference table with a polarisation component of the electromagnetic wave in the first direction and the second direction, respectively; correlating (314) the normalised eigenvector with the third reference table so as to produce a third correlation spectrum comprising correlation indices associated with different directions of arrival; identifying (316) a direction of arrival associated with a maximum correlation index of the third correlation spectrum.

A mm-wave RFID tag interrogation apparatus includes multiple transmitting antennas, and multiple receiving antennas. The transmitting and receiving antennas are spatially distributed and oriented in orthogonal polarisation states. A transmitter is coupled to the transmitting antennas, and transmits a corresponding multiple number of separable mm-wave signals. A receiver coupled to the receiving antennas is configured to extract separable components of received mm-wave signals. A processing unit processes the extracted signal components using a synthetic aperture algorithm. An RFID tag, readable by the interrogation apparatus, includes meander-line conductive elements arranged to encode information spatially on a substrate.

A laser designator system using modulated CW laser diodes and a conventional high pixel count image sensor array, such as CCD or CMOS array. These two technologies, diode lasers and imaging sensor arrays are reliable, widely used and inexpensive technologies, as compared with prior art pulsed laser systems. These systems are distinguished from the prior art systems in that they filter the laser signal spatially, by collecting light over a comparatively long period of time from a very few pixels out of the entire field of view of the image sensor array. This is in contrast to the prior art systems where the laser signal is filtered temporarily, over a very short time span, but over a large fraction of the field of view. By spatially filtering the signal outputs of the individual pixels, it becomes possible to subtract the background illumination from the illuminated laser spot.

A LIDAR device may transmit light pulses originating from one or more light sources and may receive reflected light pulses that are then detected by one or more detectors. The LIDAR device may include a lens that both (i) collimates the light from the one or more light sources to provide collimated light for transmission into an environment of the LIDAR device and (ii) focuses the reflected light onto the one or more detectors. The lens may define a curved focal surface in a transmit path of the light from the one or more light sources and a curved focal surface in a receive path of the one or more detectors. The one or more light sources may be arranged along the curved focal surface in the transmit path. The one or more detectors may be arranged along the curved focal surface in the receive path.

An Internet of Things (IoT) device can include a switch module configured to control a power supply for at least one powered device, a WiFi module configured to perform wireless communication and occupancy activity sensing, and a processor configured to determine human activity recognition WiFi measurements from the WiFi module based on the occupancy activity sensing and generate corresponding commands for the switch module based on the determined human activity recognition WiFi measurements.

A frequency modulated, continuous wave (FMCW) laser using a microchip gain medium, an optical coupling element, and a tuning element is described. The laser may be part of a coherent laser ranging system.