Lens of gradient dielectric constant and methods of production

Abstract

Disclosed is a lens of gradient dielectric constant and methods for the production of same. The lens includes an inner core comprising a cured or fused substantially homogenous blend of glass spheres, curable or fusible binder and, as needed to increase dielectric constant, a low-loss dielectric material. The inner core preferably has a dielectric constant of about 2.0, and an interstitial void volume (representing trapped air space between elements of the cured or fused material) of from about 30 % to about 50 %. The lens also includes an outer shell layer comprising a cured or fused substantially homogenous blend of hollow glass spheres and curable or fusible resin. The outer shell layer preferably has a dielectric constant of about 1.0, and an interstitial void volume of from about 30 % to about 50 %. In addition, the lens includes a minimum of one, and preferably two or more intermediate layers, the intermediate layers having a dielectric constant falling between 1 and 2. The intermediate layers are comprised of a cured substantially homogenous blend of glass spheres, resin and, as needed to increase dielectric constant, a low-loss dielectric material. As is the case with the inner core and outer shell layers, the intermediate layer(s) have an interstitial void volume of from about 30 % to about 50 %. Also disclosed are methods of production for lenses of the type described above.

Description

Background technique [0001] A lens is a device that changes the direction in which an electromagnetic wave travels as it passes through the lens. This change in direction is the result of a change in the index of refraction due to a change in the dielectric constant encountered by the electromagnetic wave as it passes from adjacent media into and through the lens. Lenses for the visible range include those used in corrective glasses, cameras, binoculars, and the like. Lenses are also used in fields related to high-frequency electromagnetic waves, such as high-frequency electromagnetic waves in the microwave band. [0002] An important subset of lenses are gradient lenses. Electromagnetic waves passing through a gradient lens will encounter a varying permittivity. A Luneberg lens is a spherical gradient lens with a defined dielectric constant gradient and has particular application in providing antennas with a very wide field of view. Specifically, current interest in them ...

AI Technical Summary

Problems solved by technology

Layers fabricated by gas expansion of the polymer matrix exhibit inhomogeneous domains with varying dielectric constants, thus degrading the performance of the lens

Also, swelling agents are usually hydrocarbons, which present flammability and toxicity issues during lens manufacture

With glass microspheres fixed in a solid resin matrix, foams made of gas encapsulated by these glass microspheres (collectively referred to as syntactic foams) cannot provide materials with a dielectric constant less than 1.4, which deviates greatly from the desired 1.0 dielectric constant, thus degrading the performance of the lens

Also, such lenses are heavy and tend to exhibit relatively high dielectric loss

Other methods, while producing satisfactory results, have proven to be prohibitively expensive