摘要:
An antenna intended for radiating and receiving electromagnetic waves and including a parabolic reflector and an exciter, which is designed as a sub-reflector and which is attached in the focal point of the reflector at the end of a waveguide, guided through the center of the reflector. On the backside of the reflector a radio box, containing electric and electronic components, is attached to the waveguide, which is connected to a transmitter-receiver. To increase the transmission capacity, a polarization diplexer is provided between the radio box and the waveguide for simultaneous transmission of two orthogonal, linearly polarized waves. The diplexer has first and second inputs with an essentially rectangular clear cross section and an output, which can be attached to the waveguide. In the polarization diplexer there are two waveguide segments, one of which runs linearly between the first input and the output of the polarization diplexer, whereas the other, starting as a 90°0 curve at the second input of the polarization diplexer, empties into the linear waveguide segment in the course of the linear waveguide segment. The linear waveguide segment is rotated by 90° in the input area so that the large axes of the two inputs of the polarization diplexer that lie in the same plane are at right angles to each other.
摘要:
An antenna includes a parabolic reflector and a supply line attached thereto. The supply line includes two rectangular electromagnetic (waveguides) that are essentially parallel to each other. A tube-shaped exciter is common to the (waveguides) and is located at open ends of the waveguides. A back side of the reflector has a mechanically stable receptacle, which is used to attach the reflector to a support. The receptacle includes a metal ring with an L-shaped cross section in an opening that corresponds to a central opening in the reflector. The ring has a cylindrical area and, at a right angle to the cylindrical area, a base area that extends toward the inside of the ring. In the installed position, the cylindrical area of the ring penetrates and is centered in the opening of the reflector. A holding plate, which firmly surrounds and supports both waveguides, fits precisely into the ring and is attached to the ring in removable form when mounted.
摘要:
A method and device for monitoring insulation and fault current in an electrical alternating current network. The differential current formed by vectorial addition is detected between at least two network conductors. Load-cut occurs when the differential current exceeds a specific threshold value. In order to increase safety and to protect human beings, the amount of alternating current contained in the differential current is detected as a first network variable, and the network alternating current between at least both network conductors and between at least one network conductor and an equipotential bonding conductor or a neutral conductor is detected as a second network variable. The product between the amplitude of the amount of alternating current contained in the differential current and the cosine of the phase angle &phgr; between both detected network variables is determined as a measure for the resistive fault current of the network and load cut-out occurs when the determined product exceeds a specific threshold value. The product can be calculated directly or, even better, it can be determined indirectly without knowledge of the individual variables. One particular advantage of this technique is that, by including DC components of the differential current, it enables work with all different types of currents in view of the fact that alternating current networks nowadays mainly consist of a large number of alternating current components which, like resistive AC components, involve fault currents endangering the lives of human beings. Thus, it is possible to ensure simultaneous protection of human beings and installations.