Reflector (antenna)

About: Reflector (antenna) is a research topic. Over the lifetime, 28730 publications have been published within this topic receiving 212618 citations.

Metamaterial Perfect Absorber Analyzed by a Meta-cavity Model Consisting of Multilayer Metasurfaces

Abstract: We demonstrate that the metamaterial perfect absorber behaves as a meta-cavity bounded between a resonant metasurface and a metallic thin-film reflector. The perfect absorption is achieved by the Fabry-Perot cavity resonance via multiple reflections between the “quasi-open” boundary of resonator and the “close” boundary of reflector. The characteristic features including angle independence, ultra-thin thickness and strong field localization can be well explained by this meta-cavity model. With this model, metamaterial perfect absorber can be redefined as a meta-cavity exhibiting high Q-factor, strong field enhancement and extremely high photonic density of states, thereby promising novel applications for high performance sensor, infrared photodetector and cavity quantum electrodynamics devices.

Endoscopic attachment to a surgical laser

Abstract: An endoscopic attachment to a surgical laser comprises a hollow endoscopic tube adapted to be coupled at its rear end to the surgical laser, a coupling device including a pivotable reflector in the path of the laser beam transmitted through the endoscopic tube for reflecting same to the working area at the front end of the tube, and a manipulatable joystick connected to the reflector for manipulating the laser beam to direct it through the endoscopic tube and to selected positions in the working area at the front end of the tube. The attachment is to be used with a surgical laser producing a working laser beam and a separate, visible, aiming laser beam, the latter being partially reflected by the reflector and partially transmitted through the reflector to permit viewing the working area. The reflector further includes a light-absorbing member located to absorb the visible light transmitted through the reflector from the aiming laser beam, but not to interfere with observing the working area through the eyepiece.

A uni-directional ring-slot antenna achieved by using an electromagnetic band-gap surface

Abstract: Slot antennas offer a number of advantages including low-profile, ease of fabrication, and ease of integration with electronics. Their main drawback, however, is that they are inherently bi-directional radiators. One common technique to redirect the back radiation forward is to place a conducting reflector at a fixed distance away from the antenna. This distance is usually chosen to be a quarter wavelength so that the reflected back radiation incurs an additional phase of 360/spl deg/ and thus adds in phase with the forward directed radiation. However, in this case the parallel-plate geometry permits the excitation of the dominant transverse electromagnetic mode, which drastically reduces the overall radiation efficiency. This work describes a solution to this problem and shows how to achieve uni-directional slot antenna elements by backing them with an electromagnetic band-gap surface, instead of the uniform conducting reflector. This structure, when operated in its band-gap, inhibits the propagation of electromagnetic waves over all possible azimuthal directions, in the region between the antenna ground plane and the periodic surface.

Vertical-cavity, surface-emission type laser diode and fabrication process thereof

Abstract: A vertical-cavity, surface-emission-type laser diode includes an optical cavity formed of an active region sandwiched by upper and lower reflectors, wherein the lower reflector is formed of a distributed Bragg reflector and a non-optical recombination elimination layer is provided between an active layer in the active region and the lower reflector.

Device for applying a high frequency electromagnetic field to living tissue to promote healing thereof

Abstract: A portable therapy device for attachment to a patient to promote tissue healing by exposure to an r.f. field, comprises an oscillator (5) which energizes an antenna having a transmitting element (1) the natural directive pattern of which is modified by a reflector (8) and a parasitic element (10) such that a major part of the r.f. field emitted by the antenna passes to the patient. In another embodiment the antenna is configured to produce a spatially substantially uniform field strength over the area of the patient being treated. The device subjects the tissue to r.f. power levels which produce no significant tissue heating.