Abstract: A construction for shielding an item against interference from a microwave radio frequency radiation is disclosed, having a wall structure adapted to minimize radio frequency interference in the vicinity of an antenna. The wall is composed of a plurality of modular wall panels, each having a layer of electrically conductive materials that substantially reflects interfering electromagnetic microwave signals. The wall structure includes a top construction creating a thin, horizontal gap in the conductive material at the wall's top that acts to control diffraction over the wall. In the preferred embodiment, the layer of electrically conductive material is a mesh of expanded metal embedded in the wall modules. The gap comprises the space between the top of the mesh and a pair of vertically adjustable metal strips mounted on the wall. In the preferred embodiment, the wall panels are precast concrete that may be horizontally positioned with a joint allowing up to 180.degree. of relative movement.

Abstract: A construction for shielding microwave antennas is disclosed including a plurality of RF reflective modular panels positioned to surround a microwave antenna location. Each modular panel has the surface of at least one side adapted to reflect RF signals away from the antenna location. The construction includes a frame for supporting the panels, and a means for connecting the panels to the frame. In the preferred embodiment, the panels are reflective of RF signals on both sides of the panel, with the side of the panel facing the antenna location reflecting RF signals upward and the side away from the antenna location reflecting signals downward. The preferred embodiment also includes dual inclined-step reflectors to achieve the directional reflection, preferrably prepared with a cross-section defining a plurality of linked Z's.

Abstract: This invention relates to an improved system for changing the bandwidth of an intelligence-bearing electrical signal so that it can be transmitted within said changed bandwidth and to a counterpart system for changing the bandwidth, following transmission, so that a good replica of the original signal is obtained at a receiving terminal. The bandwidth compression and expansion are obtained through time-delay expansion and compression. This invention uses the fact that the time delay characteristics of a charge-coupled device is a function of the clocking frequency. The desired time delay variation can be achieved by varying this clocking frequency correspondingly. A single delay line, with a sawtooth variation of clock frequency, is a feature of the invention.