Abstract: A compact electromagnetic antenna pattern range includes a planar reflector which is controllable between a reflective condition and a transmissive condition. The controllable reflector is placed parallel to a second planar reflector, and a pulse of electromagnetic energy is injected into the space between the reflectors, propagating toward one of the reflectors. After a number of re-reflections, the controllable reflector is rendered transmissive and a substantially planar wavefront is made available for application to the antenna under test.

Abstract: An electromagnetic lens formed of a refractive material with a reflective rface. The lens is a body of revolution having an upper parabolic reflective surface and spherical side and bottom surfaces. Incoming radiation is refracted at one spherical surface, reflects from the reflective surface, exits and is refracted at the other spherical surface. The radiation may be directed onto an array of electromagnetic detectors. Such an array may consist of concentric circles of detectors, such that a particular detector is illuminated by incoming radiation of a particular azimuth and elevation.

Abstract: A backfire feed antenna has a parabolic reflector with a ring-focus at the reflector focal point comprising a dielectric waveguide having a stem portion and a cap portion with a pointed end and most of the stem portion inside a conducting tube along the axis of the parabolic reflector. The outer surface of the cap portion is concave outward and convex inward and covered with a conducting layer. A curve between a parabola and hyperbola defines the surface. The cap portion has a conical surface extending between an annular surface at the junction between the stem portion and the cap portion and an axially extending circumferential surface surrounding the conducting layer. The inside end of the dielectric waveguide is pointed.

Abstract: A two reflector microwave antenna has a concave focusing main dish having an integral peripheral flange. An integral radome shell also having a peripheral flange is disposed in confronting relationship to the main dish flange. Mounted over both flanges is a clamping ring to keep the main dish and radome shell in a stress condition of fixed edge shells. A secondary reflector is provided on a central portion of the radome. The concave focusing main dish in one example, defines a paraboloid of revolution. Specific shapes of the main dish and the radome shell are selected to appropriately focus the microwave radiation. A radome portion of a variable thickness of dielectric material of the integral radome shell modify the path of microwave energy compensating for diffraction of induced edge spillover. The stress condition of the shells as maintained by the clamp about the flanges provides a structually rigid antenna substantially void of structural elements.

Abstract: A mirror antenna employing a continuous mirror without a hole. A feed horn nd an electromagnetic lens, located behind a rotatable twist reflector (the mirror), collimates a beam toward a polarized reflector located near the twist reflector and tilted to aim energy toward the twist reflector. Energy reflected back toward the polarized reflector from the twist reflector passes through the polarized reflector to free space.

Abstract: An antenna, preferably operating in the microwave range, comprising a Luneberg lens with a disc having a radially varying refraction index and provided with feeders distributed around the circumference. Each feeder has the shape of a thin wire the projection of which, as seen radially relative to the center of the round disc, forms a straight line inclined 45.degree. against the plane of the disc. All feeders are inclined in the same direction in their respective radial planes, whereby the feeders opposite a respective feeder will be oriented substantially perpendicular to the feeder permitting passage of radiation to and from the feeder. All of the feeders can be active simultaneously.

Abstract: A reflector antenna comprising a reflector system, and a feed system, for instance a log-periodic feed system, the phase center of which moves with frequency, for illuminating the reflector system to produce a substantially focussed antenna beam. To compensate for frequency variations in the position of the phase-center of the feed system, the reflector system includes a frequency dependent reflector the effective surface of reflection of which varies with frequency to cause the focus of the reflector system to move with the phase-center of the feed system. A number of different forms of suitable frequency dependent reflectors are described, employing composite arrangements frequency selective mesh or grid reflector elements, or arrays of reflecting horns or wedges.

Abstract: Disclosed is an antenna system designed to operate in two frequency ranges imultaneously, namely S-band (1660 to 1700 MHz) and X-band (8500 to 9600 MHz). The system comprises two separate antennas which are conically scanned and share a common parabolic reflector within a radome. The S-band antenna is adapted for passive angle tracking and reception of radiosonde data by means of a balun fed dipole feed system which includes an offset hemispherical reflector which is rotated by a scan motor to provide conical scanning. The X-band antenna comprises an active feed system which includes a stationary feedhorn and a tapered dielectric lens which is coupled to the S-band hemispherical reflector and is rotated therewith about an axis through the vertex of the parabolic reflector. The tapered lens tilts the constant phase front of the X-band radiation pattern thereby producing a displaced phase center near the focus of the antenna to implement its respective conical scanning operation.

Abstract: An antenna, preferably operable in the microwave range, comprising a disc-shaped lens having a radially varying refraction index, and having feeders distributed around the circumference. Each feeder is in the shape of a thin wire having a projection which, as seen radially relative to the center of the disc, forms a straight line inclined 45.degree. relative to the plane sides of the disc. All feeders are inclined in the same direction relative to the center of the disc and thus all diametrically-opposed feeders are oriented substantially perpendicular to each other. Because of this orientation, radiation focussed by the lens passes to and from any active feeder without being substantially disturbed by other feeders, and a plurality of feeders can be active simultaneously.

Abstract: An aperture antenna having the improved phase performance of radiated co- and cross-polarization has been found. The present antenna has, at least, a horn for radiating an electro-magnetic wave, and means for focusing the electromagnetic wave. The focusing means is actually implemented by a reflector or a dielectric lens, and is designed so that the phase distribution of an electric field on an aperture plane of the focusing means has the period of .pi./2 and the maximum phase at (2m-1) .pi./8 from the reference plane of one polarized wave in the polar coordinates system on the aperture plane, where m is an integer.

Abstract: An antenna system having a multiple of antenna feeds to drive a microwave ns, composed primarily of a Luneberg lens and a metallic ground plane upon which are mounted three antenna feeds and a shorted stub (or four bent-stub coaxial feeds). The antenna system uses a common aperture to provide antenna performance for the three separate feeds, conserving space that would normally be required for three separate high gain antennas.

Abstract: An antenna and a method for obtaining predetermined far field antenna patterns is disclosed. Empirical adjustments of a focal region feed system provides for the compensation of tolerance or other imperfections of the antenna to achieve the desired far field pattern. An element of the feed system is adjusted when the antenna is angularly positioned, with respect to a receiving element in the far field, which corresponds to the location of the element in the feed array. A desired far field pattern may also be achieved by illuminating the antenna aperture, either simultaneously or sequentially, by several plane waves, the amplitude and incident angles of which are carefully controlled, measuring the phase and amplitude of the focal region distribution caused by this illumination, and designing the feed system to establish a focal region distribution that is the complex conjugate of that measured.

Abstract: A multifrequency, broadband, dual-polarized corrugated conical horn antenna is simultaneously fed a multiplicity of signals, two for each of five frequencies, with each of a pair of signals fed in each of two orthogonal planes for excitation of a desired spherical hybrid mode (HE.sub.11). The lowest frequency is fed into the horn through orthogonal pairs of colinear slots, each pair being fed by coaxial tee power dividers. Other signals are fed through a circular waveguide connected to the vertex. Band reject cavities block the next higher frequency from passing through the low frequency feed slots. The highest frequency signals are fed through orthogonal ports near the far end of the circular waveguide. The intermediate frequency signals are fed through orthogonal ports spaced along the waveguide.

Abstract: A feature of this invention is the provision of an antenna system providing two, coaxial, copolarized, independently focused beams: a relatively wide, low frequency, searching beam, and a relatively narrow, high frequency, tracking beam; and comprising a dual frequency, dual polarization feedhorn; a polarization dependent subreflector; a concave polarization reversing reflector; a concave polarization twisting reflector; and a planar frequency dependent dielectric lens.

Abstract: Disclosed is an antenna feed system for use in satellite communication systems and the like, comprising a horn with a rectangular aperture and a waveguide connected thereto. The assembly formed by the waveguide and horn is constructed from two parts secured together so that the junction lies in the longitudinal symmetry plane parallel to the electric field of the TE.sub.01 mode and is mounted for rotation about the longitudinal axis of the waveguide. The feed system further comprises a polarization converter mounted in front of the horn for rotation about the extention of the longitudinal axis of the waveguide. The converter is constructed from a plurality of layers of supporting material each provided with a conductor which forms in one direction a mainly inductive load and in a direction which is perpendicular thereto a mainly capacitive load.

Abstract: A feed horn mounted within a streamlined enclosure upon the top surface of a wing of an aircraft at an outwardly-spaced location to direct electromagnetic wave energy toward the face surface of a dielectric slim lens having a metallic reflector between the lens and the fuselage of the aircraft to effect a double-traversal of the incident wave energy. The metallic reflector is planar or parabolic to trim the aerodynamic cross section. When the metal skin of the fuselage is used as the reflector, the dielectric constant of the lens is modified by varying its thickness to produce a very sharp beam by compensating for the curvature of the fuselage at the lens support site.

Abstract: An antenna of the discone type is omnidirectional in bearing and has a diagram whose directivity in elevation can be adjusted. At the apex end of each cone a dielectric disc of predetermined thickness is inserted parallel to the base of the cone concerned. In the central portion of the antenna these two discs create conditions for the propagation of energy which are different from those existing outside the discs, the result being an improvement in the phase pattern in the radiating aperture of the antenna.

Abstract: The high-power, short-pulse array is a self-contained radiating oscillator system which radiates a high peak-power pulse of radio frequency energy. The radiated pulses contain only a few cycles of RF and hence it is a short-pulse emitter. The device contains a chain or a series of loops which radiate in phase and each loop has a spark gap. The spark gaps are sequentially fired. The radiated waveform can be a single pulse of RF or a train of RF pulses. The device requires only a high voltage power supply for operation.

Abstract: In a switchable beamwidth monopulse method and system, an antenna comprising a curved reflector and a first set of monopulse feeds positioned in the effective region of the Airy disc of the antenna includes a second set of monopulse feeds. The second set of monopulse feeds is positioned outside the Airy disc in the region of first bright Airy ring. In narrow beamwidth monopulse operation, monopulse sum and difference channel patterns are obtained from the first set of feeds within the Airy disc. In wide beamwidth monopulse operation, the difference channel pattern is obtained from the second set of feeds in the Airy ring; the sum channel pattern is obtained by attenuation and phase shifting the sum channel signal obtained from the first set of feeds, and adding the resultant to the sum channel signal obtained from the second set of feeds.