Abstract: A thermally emissive apparatus (2) having an electro-thermal heating element (6) comprising a layer (8) of a first material having a first resistivity and a plurality of discrete regions (10) of a second material having a second resistivity substantially lower than that of the first material in electrical contact with the first material. The plurality of regions (10) of second material are arranged spatially so as to impart a predetermined effective sheet resistivity to the first layer (8). A plurality of heating elements may be used having a common first layer (30) of first material, wherein the spatial arrangement of the regions (10) of second material within a first heating element are optionally different to that within a second heating element. In this configuration the first and second heating elements may emit infrared radiation (14) having different intensities. The apparatus (2) finds applications as a thermal target and as an electro-thermal ice protection device.

Abstract: Some embodiments are directed to an antenna for use in interrogating RFID tags in close proximity thereto. The antenna can include an active element configured to resonate at or close to a frequency required to read an RFID tag, the active element comprising a feed point; and a plurality of passive elements, each passive element being configured to resonate at or around a frequency corresponding to said frequency, the passive elements being arranged around the active element such that the passive elements electromagnetically couple to the active element when the active element is driven by a signal supplied through the feed point.

Abstract: An optical multilayer (1) comprising textured surfaces suitable for use in anti-counterfeiting and/or security applications is described.

Abstract: A thermally emissive apparatus (2) having an electro-thermal heating element (6) comprising a layer (8) of a first material having a first resistivity and a plurality of discrete regions (10) of a second material having a second resistivity substantially lower than that of the first material in electrical contact with the first material. The plurality of regions (10) of second material are arranged spatially so as to impart a predetermined effective sheet resistivity to the first layer (8). A plurality of heating elements may be used having a common first layer (30) of first material, wherein the spatial arrangement of the regions (10) of second material within a first heating element are optionally different to that within a second heating element. In this configuration the first and second heating elements may emit infrared radiation (14) having different intensities. The apparatus (2) finds applications as a thermal target and as an electro-thermal ice protection device.

Abstract: A substrate including a surface on which is provided a modifying layer which is incomplete and has a distribution such as to provide a plurality of islands of said material and/or islands of substrate surface whereby the surface exhibits a modified electrical and/or magnetic property.

Abstract: An electromagnetic radiation absorber for absorbing radiation in the wavelength range ?min to ?max. The absorber has a conductor layer in contact with a dielectric layer. The conductor layer carries a plurality of apertures of sub-wavelength dimension and the thickness of the absorber is less than ?min/4n, where n is the refractive index of the dielectric. The dielectric layer may be sandwiched between two conductor layers, one of which has the structure described above. The invention is also directed to various articles comprising such an absorber.

Abstract: A substrate (2) has a surface on which is provided a modifying layer which is incomplete and has a distribution such as to provide a plurality of islands of said material and/or islands of substrate surface whereby the surface exhibits a modified electrical and/or magnetic property. As shown, substrate (2) is piezoelectric, and has a central electrode (9) and a peripheral electrode (10), between which are deposited a large number of electrically conductive dots having a dot density which decreases with distance from electrode (9). The construction acts as a sonar transducer over a relatively wide frequency range.