(under subclass 700) Subject matter wherein the active antenna is combined with structure spaced from or external to the active antenna which transmits waves going to or from the active antenna, and is shaped or positioned to delay or accelerate transmitted waves an amount which varies over the wave front, to alter the direction or propagation of the waves emitted from the structure with respect to the waves impinging on the structure, or to bring the wave to a focus, or to alter the wave front (such as to convert a spherical wave front to a planar wave front or vice versa).
(1) Note. The structure referred to above may be contiguous to a reflecting plate or may form with the surrounding fluid (as air) a reflecting surface (by reason of the different dielectric constants of the structure material and air) so that the impinging waves pass through the wave modifying structure twice, once on the way to the reflecting surface and then returning therefrom, in going to or from the active antenna, thus forming a reflecting lens. This subject matter is classified in indented subclass 755.
(2) Note. In the case of directors which are constructed of somewhat smaller dimensions than the resonant active antenna with which they have a parasitic relationship, so that the phase retardation at the ends or edges of the director sharpens the beam resulting in a type of "focusing" action, the impinging electromagnetic wave cannot be said actually to pass therethrough; and antennas with such directors are therefore not classified herein but in subclasses 815, 817, 819, and 833.
(3) Note. When the active antenna is a wave type guide horn, the term "spaced" means physically removed externally from the mouth of the horn. A lens at the mouth of the horn and forming a closure for this mouth is not deemed "spaced" as here used, but is classified in subclass 783 below. The term "external" means on the outside of the active antenna.
(4) Note. An active antenna with a so-called diffractor, which produces an interference pattern is classified here, if
the diffractor transmits electromagnetic wave energy. If the diffractor is opaque to such energy, classification is on other characteristics, such as in subclass 833 if the director function is performed and in subclasses 834+ if the reflector function is performed.
SEE OR SEARCH THIS CLASS, SUBCLASS: 756, for antennas with polarization filters or converters.
783, for wave guide type antennas having internal wave refraction means.
784, for wave guide type antennas with closures.
785, for wave guide type antennas composed of dielectric rods, e.g., polystyrene rods.
872+, for antennas having a housing or protective covering which may be of material having refracting properties.
909+, for refracting means and radiant energy filters, per se.
SEE OR SEARCH CLASS
333, Wave Transmission Lines and Networks, particularly
245+, for transmission line elements and components which may be refractors in a transmission line.
359, Optics: Systems (Including Communication) and Elements,
642+, for optical lenses.
362, Illumination, 326+, for illumination type refractors.
