Parabolic reflector

About: Parabolic reflector is a research topic. Over the lifetime, 3375 publications have been published within this topic receiving 30735 citations. The topic is also known as: paraboloid reflector & paraboloidal reflector.

Reflector system and projector

Abstract: PROBLEM TO BE SOLVED: To provide a technique for improving optical quality when an emitted light from a lamp bulb is utilized in a projector. SOLUTION: A cylindrical lens 132 is arranged as a focusing means in between the lamp bulb 122 of the projector and a parabolic reflector 131. The parabolic reflector 131 is declined in its section to bring a forward end 131b close to an optical-axis side Z0 in an illuminating system. Further, a cone lens 133 is disposed ahead of the parabolic reflector 131 to convert the light reflected by the reflector to the light parallel to the optical-axis Z0 in the illuminating system. COPYRIGHT: (C)2010,JPO&INPIT

Dual gridded reflector antenna

Abstract: An improved dual gridded reflector antenna configuration which allows cross-polarization radiation to be scanned in any given direction. The dual-gridded reflector assembly includes a front parabolic reflector illuminated by a first source, and a second parabolic reflector illuminated by a second source. The second reflector is positioned adjacent to and behind the front reflector such that the center points of the reflectors align to define a center axis. Additionally, the first and second sources are positioned at different offsets with respect to the reflectors and have a respective rotated offset angle with respect to the center axis such that the sources define an antenna feed separation. By modifying the offsets and the rotated offset angles, the feed separation can be designed to have an inclination with respect to the north-south or east-west feed separation direction.

Hand-held forward-looking focused array mine detection with plane wave excitation

Abstract: A novel handheld time-domain array GPR antipersonnel mine detection system prototype has been developed. Using an offset paraboloidal reflector antenna to collimate rays form an ultra-wideband feed, the transmitted microwave impulse is concentrated forward, in front of the antenna structure. The resulting wave is a non-uniform plane wave over the portion of ground be investigated, and is incident at 45 degrees to normal. As such, much of the ground reflect wave is directed further forward, away from the operator, the reflector, and the receiving antennas, thereby reducing clutter. However, the wave transmitted into the ground, which interacts with the target, tends to have significant backscatter returning toward the receiving antennas. These receiving antennas are configured in a 2 by 2 array to provide spatial focusing in both along and cross-track directions. This is accomplished by measuring and comparing the backscattered signal at each receiver in the narrow time window between the times when the ground reflected wave passes the receiver and before this wave re-reflects from the reflector components. 2D FDTD simulation of this parabolic reflector transmitter indicates that it generates a beam with a non-uniform planar wavefront, which scatters form rough ground primarily in the forward direction. The wave transmitted into the ground is also planar, propagating at the angle of refraction, and scattering fairly isotropically from a small penetrable target. This system has been built and tested at LLNL, using a very narrow pulse shape. LLNL's Micro-Impulse Radar (MIR) and custom-built wideband antenna elements operate in the 1.5 to 5 GHz range. One particular advantage of using the MIR module is its low cost: an important feature for mine detectors used in developing countries. Preliminary measured data indicates that the surface clutter is indeed reduced relative to the target signal, and that small non-metallic anti-personnel mines can be reliably detected at burial depths as shallow as 1 inch in both dry.