Abstract: This invention is directed to a apparatus that includes an inflatable antenna reflector assembly for generating electromagnetic plane waves. The apparatus can be used in a variety of applications in which plane waves are beneficial, such as in a compact range to simulate the long-range behavior of a radar system to test a target for its radar signature. The inflatable reflector assembly of the apparatus includes a base, an arched frame mounted to the base, and an envelope-like cover that fits over the frame. The cover's front side is transmissive to electromagnetic waves, and its rear side is reflective to such waves. The apparatus can include a point source antenna feed, in which case the cover's reflective portion is made to be parabolic, or the antenna feed can be a line source, in which case the cover's reflective portion is spherical. The base can be rested directly on the floor or ground for support.

Abstract: This invention is directed to an apparatus for transmitting an electromagnetic wave. The apparatus includes a dielectric material with a permittivity that decreases with increasing frequency over an operating frequency bandwidth that includes the frequency of the electromagnetic wave. With this behavior, the electrical or phase length of the dielectric material remains relatively constant and independent of frequency over the operating band, a feature that is highly advantageous for many important applications including circuit boards, radomes, and antennas. In addition, the dielectric material can be engineered to exhibit this behavior at a desired frequency, including frequencies in the millimeter, microwave, VHF and UHF frequency ranges. In a preferred embodiment, the dielectric material is an artificial dielectric manufactured by mixing conductive particulate into a host dielectric material.

Abstract: A window construction and method are presented for electromagnetic signal transmission having broad bandwidth capability plus excellent resistance to ablation, rain erosion and thermal shock. The window is constructed of an odd number of three or more (i.e., 3, 5, 7, etc.) layers of reinforced PTFE material, with the dielectric constant of each layer (other than the core layer which is selected) being equal to the square root of the product of the dielectric constants of the two bordering layers. In a three layer version, the outer layers each have a dielectric constant which is the square root of the dielectric constant of the center layer; or, stated conversely, the center layer has a dielectric constant which is the square of the dielectric constant of each of the outer layers.