Reflector (antenna)

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

Directional antenna, in particular dipole antenna

Abstract: In order to produce a directional antenna which is superior to those of the prior art, and especially a dipole antenna which is easier to manufacture and of simpler design, and also has enhanced electrical properties, the dipole with its circuit balancing element (7) according to the invention is made of the material of the reflector (5). The dipole and the circuit balancing element (7) project from the reflector wall (5) through corresponding areas which are cut out and/or punched out, up to a region (11) where they join with the remaining material of the reflector wall (5), and are preferably bent outwardly in relation to the plane of the reflector wall in the region of the point (11) where they immediately join with the remaining material of the reflector wall (5).

Analytical solution for early-time transient radiation from pulse-excited parabolic reflector antennas

Abstract: A closed-form analytical solution is developed for predicting the early-time transient electromagnetic fields which are generated by a perfectly conducting parabolic reflector antenna when it is illuminated by a transient step spherical wave due to an elemental Huygen's source located at the focus. This closed-form time-domain solution, which is valid both near and far from the reflector (and anywhere in the forward region) can be used via the convolution theorem to efficiently obtain the early-time transient fields generated by the same parabolic reflector antenna when it is illuminated by a realistic finite-energy pulse which emanates as a spherical wave from the focus. The transient solution is developed here by analytically inverting, in closed form, the corresponding frequency-domain solution in terms of a radiation integral that employs an asymptotic high-frequency geometrical optics (GO)-based approximation for the fields in the aperture. Numerical results are presented for the transient fields both near and far from the reflector. The fields on boresight exhibit an impulse-like behavior similar to that of the impulse radiating antenna (IRA) introduced by Baum et al. (1989, 1993).

Bottom reflector for a radar-based level gauge

Abstract: A bottom reflector for a radar-based level gauge, which measures a level of a liquid stored in a tank by means of transmitting a microwave signal towards the surface of the liquid from the top of the tank, receiving the microwave signal as reflected against the surface of the liquid, and calculating the level of the liquid from the propagation time of the transmitted and reflected microwave signal, wherein the bottom reflector is adapted to be mounted close to the bottom of the tank and comprises a reflecting structure having a first reflection coefficient for the microwave signal when the level of the liquid is above the reflecting structure and a second reflection coefficient for the microwave signal when the level of the liquid is below the reflecting structure, wherein the first reflection coefficient is substantially lower than the second reflection coefficient.

Maximum reflectance of multilayer dielectric mirrors in the presence of slight absorption

Abstract: A new design technique for multilayer reflectors is presented It is useful when slight absorption by one or both of the coating materials limits the performance of the reflector. The basic procedure is to add layers to a given substrate or multilayer system one pair at a time. The thickness of each layer is chosen to give the maximum increase in reflectance for each pair of layers added. In general, the optical thicknesses of the layers in each pair are not quarter waves, but depend on the optical constants of the materials, as well as the starting reflectance of the subsystem. By using such optimized pairs, it is possible to exceed the reflectance limit usually imposed on quarter-wave stack reflectors by absorption. Expressions for the optimum design and the ultimate reflectance for a high reflector made with a given set of coating materials are given. Other design techniques found in the literature require more layers to achieve the same level of reflectance as the present method.

Apparatus, method and system for fluid-motion-powered modulation of a retroreflector for remote position sensing

Abstract: A fluid-motion-powered modulated reflector apparatus is provided that modulates the frequency of a reflected radiation signal. Passing the apparatus through a fluid such as air causes rotational velocity of a chopping wheel or, in some instances, a polarizing filter rotatably connected to propeller blades. The radiation signal is modulated by the blocking effect of a chopping wheel or a fixed polarizing filter and a rotating polarizing filter. The apparatus also can include a frequency selector to control the rotational velocity of the chopping wheel or rotatable polarizing filter. A fluid-motion-powered modulated reflector system may include an array of fluid-motion-powered modulated reflectors, each differently modulated by a frequency selector to allow a position sensor, such as a duo-lateral photodiode position sensing detector, and position determining system, to locate and determine the position of each individual retroreflector simultaneously. This system can be used for aerial refueling of unmanned combat air vehicles.