Abstract: An electrostatically figured directional antenna array for deployment in outer space having means for suppressing sidelobe responses. A portion of the reflector surface symmetric about its center is vibrated by electrostatic controls to change the amplitude and phase of the sidelobe signals whereby the latter can be eliminated by passive filters or time averaging circuitry.

Abstract: A bootlace microwave lens antenna has orthogonal delay lines for reducing adratic phase errors to improve focusing capability. The collector and radiator elements consist of mutually orthogonal pairs of subelements with one of the subelements oriented radially and the other oriented tangentially on the respective collector and radiator surfaces. Individual delay lines interconnect corresponding radial and tangential subelements on each surface thus allowing for phase corrections in the axial planes parallel to and perpendicular to the plane of scan by the introduction of an appropriate phase delay in each delay line.

Abstract: An adjustable bracket mount for mounting certain functional components such as a feed horn and a low noise amplifier on a satellite antenna dish at the prime focus or other desired location above the antenna dish, which mount includes a base secured to the dish, a bottom support extending from the base toward the prime focus, an offset bracket in adjustable cooperation with the bottom support and carrying a top support which extends in parallel relationship to the bottom support and projects above the bottom support and a top bracket adjustably mounted on the top support to carry the functional components.

Abstract: A compact antenna feed system for orthogonally polarized RF signals includes a waveguide feed having orthogonally disposed internal ridges, a pair of wave detectors coupled to the waveguide feed to receive orthogonally oriented RF signals, and an amplifier housed as part of the feed system to amplify received RF signals prior to communication of the signals outside the feed system. The system is readily switchable by remote control to receive RF signals in either orientation and angular alignment to the orientation of the incoming signals is easily accomplished.

Abstract: A multifrequency antenna includes a main reflector for signals in a low frequency band. One or more portions of the main reflector are deformed to provide one or more auxiliary reflectors for signals in one or more higher frequency bands. The feed for the low frequency band is located axially of the main reflector, while the feeds for the higher frequency bands are offset to the side of the low frequency feed. The lateral and axial offsets of the vertex of an auxiliary high frequency reflector from the vertex of the main low frequency reflector and the focal length of the auxiliary high frequency reflector are selected to minimize the degradation of the performance in the low frequency band.

Abstract: A receive only, low cost, small size, frequency agile earth satellite ground station has the low noise amplifier, frequency agile receiver, head end modulator, motor control circuit and optional signal unscrambler disposed on circuit boards about a variable polarization antenna-to-low noise amplifier feed which together with the motor for controlling the feed polarization of the feed are all located in a weather insulating cannister at the focal point of the system antenna whereby the only elements of the system not located in the cannister are the antenna and a cable connected control console employed to select a desired channel and to select local or satellite reception located at the TV set. A motor control is provided which senses odd-or-even least significant bit of binary coded channel selection signals to determine if the feed polarization, control motor must be energized.

Abstract: Earth station antenna and method for assembly wherein the antenna has a frame made up of accurately stamped radial ribs and circularly disposed cross members, the frame being filled in by either sheet metal segments or by screen mesh segments to form a parabolic surface. The ribs are supported by a central ring or barrel, which is rotatable during assembly, and by back braces which are adjustable to bring the ribs to true parabolic positions and to tune the completed antenna. Assembly may be done from the ground by rotation of the central barrel. Novel connection means and a positioning gage are used during assembly of the antenna.

Abstract: A sectional parabolic reflector of improved construction comprising two similar parabolically curved half-reflector sections each having a longitudinal parabolic axis and a reflecting surface, a mount for said half-reflector sections, said mount and said half-reflector sections being separately formed, said mount and said half-reflector sections being formed for manual manipulation together at joints, said mount and half-reflector sections when manipulated together at said joints locking against movement of the half-reflector sections towards each other when they assume an operational position wherein their reflecting surfaces combine in a common parabolic surface, locking means extending between each of said half-reflector sections at a location spaced from said joints and for locking said joints to maintain said half-reflector sections with their reflecting surfaces in said operational position.

Abstract: A portable lightweight folding parabolic reflector antenna for reception of microwave signals includes an axial waveguide tube which constitutes the main structural supporting member of the antenna, a ten- to fifteen-foot diameter dish mounted to the waveguide and a sub-reflector supported at the forward end of the waveguide. A low noise amplifier may be mounted to the rear end of the waveguide for amplification of the received signals. The folding dish includes a single sheet of resiliently elastic reflecting mesh supported by a radial framework of normally straight resiliently flexible spokes of tapering cross section. The spokes are pivotable by a lever system between a folded axial position and a deployed radial position.

Abstract: The directivity as well as the gain of an antenna element associated with a finite length reflector, which includes a feed antenna such as a dipole antenna and a reflector having a finite length of several wavelengths or less, are improved by disposing a non-feed loop element having a peripheral length of about 2 wavelengths along a common imaginary plane with the feed antenna so as to surround the feed antenna. Preferably, the non-feed loop element is disposed in parallel to the reflector, and more preferably it is disposed nearly symmetrically with respect to the center of the feed antenna.

Abstract: There is disclosed herein an antenna, particularly for use at high frequencies such as approximately one gigahertz and above, which is frequency selective. The antenna design allows signals at a given frequency to be preferentially received, as distinguished from broadband reception. The antenna design can be modified for reception of signals of different given frequencies. The antenna comprises a plurality of parabolic sections in the form of concentric rings or segments with each segment being offset axially from the next adjoining segment to thereby provide an antenna which is relatively flat, or having a low profile, as compared to a standard parabolic antenna. The surface of each segment is a segment of a different focal length parabola, but with each parabolic surface being a function of the signal wavelength (or frequency) to be received by the antenna. The antenna may be round, rectangular or have other shapes. Also disclosed are feed and pick-up arrangements for the antenna.

Abstract: The aftermath of a nuclear explosion generates a large amount of heat or infrared energy. When this heat is received by a parabolic reflector type antenna, the level of heat concentrated on the focal area of the feed is very intense. The present invention utilizes a highly heat conductive ceramic plug between the splash plate at the focal area of the feed and the waveguide so that heat can be readily conducted away from the splash plate and thereby minimize operational destruction of this splash plate due to thermal overload. The heat conductor material is a ceramic which is substantially transparent to RF signals being received by, or transmitted from the waveguide of the antenna system.

Abstract: A parabolic, collapsible rooftop microwave antenna for direct satellite-to-consumer TV transmission pivots in the direction of the aperture axis about a horizontal pivot axis in response to excessive wind forces. The antenna has a cross-head theodolite-type mount adjustable for azimuth and elevation, with a horizontal pivot that provides axial displacement if the axial wind force exceeds a predetermined threshold force. This limits the torque transmitted to the roof on which the antenna is mounted to a reasonably low level. Various torque sensitive horizontal pivots are described including a torqued pivot bolt, torqued slide bolts disposed in arcuate slots for limit-stop action, shear pins for quick release action, and biased springs for collapse and self-restoration to the initial vertical position in response to transient wind force exceeding a threshold force set by the spring bias.

Abstract: Directive antenna or radio telescope systems in which a large aperture objective directs incident electromagnetic energy onto a relatively much smaller field element which in turn directs it upon a small directive feed such as a phased array.

Abstract: A microwave antenna has associated therewith an integrated amplifier and frequency converter circuit for operating frequencies of from 1 Ghz to 40 Ghz. The circuit may be tuned by variation of a voltage regulated supply which is impressed onto the center conductor of a coaxial output cable. The frequency selective tuning elements are strip lines etched on one side of a double sided printed circuit board. The receiver is designed as an integral part of a quarter spherical reflector which illuminates a resonant cavity in which a stub antenna is mounted. The stub antenna is also directly connected to an input transistor of the amplifier/converter circuit.

Abstract: The present invention relates to an antenna arrangement which uses an imaging reflector (10) combined with a small feed or horn (14) which is capable of launching or receiving a spherical wavefront (18) to obtain a nearly frequency independent field distribution over a large antenna aperture. The antenna arrangement comprises a parabolic main reflector (10) disposed confocally with one focal point of a subreflector means (12) and a feed (14) disposed with the apex of the spherical wavefront at the other focal point of the subreflector means and the aperture of the feed centered on the image of the main reflector. If the rim of the feed aperture corresponds to an image of the edge of the main reflector, spill-over is substantially eliminated. Generally, any feed arrangement comprising a feed and subreflector means which transforms a spherical wavefront from the feed into a spherical wavefront emanating from the focal point of the parabolic main reflector can be used.

Abstract: Method and apparatus for determining the focal axis (26) of an asymmetrical antenna (14) such as an offset paraboloid reflector whose physical rim (15) is not coincident with the boundary of the electrical aperture but whose focal point is known. A transmitting feed horn array (34) consisting of at least two feed horn elements (36, 38) is positioned asymmetrically on either side of an estimated focal axis (40) which is generally inclined with respect to the boresight axis (12) of the antenna. The feed horn array (34) is aligned with the estimated focal axis (40) so that the phase centers (CP.sub.1, CP.sub.2) of the two feed horn elements (36, 38) are located on a common line (42) running through the focal point (F) orthogonally with respect to the estimated focal axis. RF circuit means (44) are coupled to the feed horn elements for generating RF electric field components which are directed to the offset antenna (14) whereupon sum and difference radiation far field patterns (.SIGMA., .DELTA.

Abstract: An orthogonally-polarized microstrip patch radiator feed structure comprising a cavity of circular cross section, a microstrip radiation emitter including a first ground plane at the bottom of the cavity, a first non-conductive substrate overlying the first ground plane, a circular conductive transmit patch on the first substrate, and a first input line on the first substrate extending radially to the transmit patch, and a microstrip radiation receiver, including a second non-conducting substrate overlying and spaced from said first substrate, a second ground plane on the inner surface of the second substrate in the form of a first array of spaced parallel conductive bars orthogonal to the radius of the first input line, a circular receive patch on the outer surface of said second substrate in the form of a second array of spaced parallel conductive bars aligned with the bars of the first array, and a second input line of the second substrate connected to the receive patch and extending radially in a directio

Abstract: A bifunctional antenna of a primary/secondary radar system comprises a reflector having a concave front surface illuminated by a source of primary radiation and formed with a row of circular ports along a horizontal generatrix, the ports lying forwardly of respective cavities or waveguides of cylindrical configuration excitable to emit circularly polarized secondary radiation. In some embodiments the polarization may be changed to a linear or an elliptical mode under the control of inserts rotatable about the cavity axis.

Abstract: The invention provides an antenna having a large area reflector formed of a plurality of conductive slats of carbon fibre re-inforced plastics material having air gaps therebetween. The slats are mounted on a supporting and shaping framework which is of like material. The supporting and shaping framework is carried on a support structure of aluminium and between the aluminium and the support structure and the carbon fibre reinforced plastics material of the supporting and shaping framework is provided the intermediary material (e.g. titanium or stainless steel provided to reduce the effects of electrolytic corrosion.

Abstract: Disclosed is an expandable panel and truss structure capable of being stowed in a storage container (canister) for transportation into space and deployed to form structures such as antennas, solar panels or similar space or terrestial structures. The antenna formed comprises the panels stored as hinged pairs (sets) folded in accordian-like fashion together with the expandable trusses and other devices necessary for antenna space operation, such as attitude control and antenna feed. The panel sets are deployed from the canister to form a toroidal ring, circular in cross-section when deployed, for supporting the antenna lens and to form a feed support boom utilizing the canister as part of the antenna structure. The canister is connected to the ring and support boom in the deployed state by the expandable trusses. A fully automatic system is included for deploying the antenna and for holding the antenna structure in its deployed state.

Abstract: The present invention relates to wideband antenna arrangements for suppressing selected sidelobes comprising a main antenna (10) comprising a predetermined aperture (l) and two sidelobe suppression means (12, 14, 40, 42) disposed adjacent and on symmetrically opposite sides of the main antenna in the plane of the sidelobes to be suppressed. The distance between the suppression means preferably approximates the width of the aperture of the main antenna and the aperture size of the suppression means controls the sidelobe suppression region at the aperture of the main antenna. The suppression means can comprise two auxiliary antennas or two sections of the main antenna focusing reflector having apertures (l.sub.1) which are smaller than that of the main antenna.

Abstract: Apparatus for cooperation with an associated antenna for prevention of the formation of ice and/or removal of accumulated ice which includes apparatus for enclosing a substantial portion of the convex face of the antenna to define a plenum chamber and apparatus for burning a fuel to create heat. The apparatus for burning is disposed at the plenum chamber. Apparatus is also provided for distributing heated air to the geometric extent of the plenum chamber. The associated antenna may be generally dish shaped and may have a truss supporting frame. The apparatus for enclosing may include a plurality of discrete panels dimensioned and configured for engagement with the truss work of the associated antenna. The invention also includes a bracket that includes a generally U-shaped bracket and a generally planar member.

Abstract: A correction method for transverse defocussing of paraboloid oriented relative to the source initially aligned with the focus consists of securing said paraboloid to first platform, articulating said first platform through hinge means jointed to second platform, itself articulated through further hinge means jointed to a stationary part, and then orienting said hinge means to said focus, while providing moving means for said platforms, said moving means being servocontrolled responsive to pointing error detector thereby to hold permanently said focus close to the source.Provision is also made of a parabolic antenna comprising means for carrying out said method. The system is applied to radio and TV broadcast apparatus aboard satellites.

Abstract: The present invention relates to an antenna arrangement for suppressing selected sidelobes where the arrangement comprises a main focusing reflector (10), a main feed arrangement (14) and at least two auxiliary feed arrangements (20 and 21) disposed on opposite sides of, and a predetermined equal distance from, the main feed arrangement in the plane of the sidelobes to be suppressed. All feed arrangements radiate the same signal and their individual beams are radiated in a direction whereby the central ray thereof impinge the same point on the main reflector. By proper adjustment of the phase, amplitude and transverse off-axis distance of the auxiliary feed arrangements from the main feed arrangement, the combined E-field distribution of the auxiliary feed arrangements at the edge of the reflector in the plane of the sidelobes to be suppressed will be equal and opposite to the E-field distribution of the main feed arrangement.

Abstract: A spherical reflector of microwaves is formed by a thin metallic coating laminated to the inside of a semi-hemispherically formed thin plastic sheet joined equatorially by a short rigid cylindrical support member to another thin semi-hemispherically formed thin plastic sheet which is transparent to microwaves. A thin wall plastic tube which is transparent to microwaves is externally joined to and extends through the cylindrical central support member at the focal plane of the reflector to provide trunnions fitting external bearings in a mounting frame to enable adjustment of antenna beam elevation angle. The interior of the trunnion tube provides support and variable positioning for the antenna feed along the focal plane for limited adjustment of antenna beam azimuth angle.

Abstract: This specification discloses a microwave antenna system using an offset J-hook feed to achieve low sidelobe energy level over the entire radiation space from an electrical circular reflector antenna. An electromagnetic horn is positioned along the central axis of symmetry of a parabolic reflector. A waveguide feed is coupled to the horn and intersects the reflective surface at a position offset from the axis of symmetry.

Abstract: A lightweight inexpensive fiberglass antenna dish is disclosed, as well as a method for the manufacture thereof. The dish may be formed by spraying chopped fiberglass and epoxy binder onto the glazed surface of a parabolic mold. An aperture formed on the focal axis of the antenna dish, either at the time of molding or at a later time, accommodates a heavy wall structural tube which extends along the focal axis half-way towards the focal point and which is secured to the dish. Rods secured between the dish surface and the distal end of the tube form triangular shapes in cross-section which rigidify the dish element. The feed unit, such as a horn, is attached to the distal end of the tube and the transmission lines therefore can pass through the tube itself.

Abstract: An antenna arrangement for a radar surveillance method for target locating having altitude acquisition provides that, for the purpose of level comparison, a plurality of overlapping lobes lying above one another are generated by a reflector rotating around a vertical axis together with a primary radiator row arranged essentially vertically. In employing a paraboloid of revolution as the reflector, a vertical primary radiator row is arranged around its focal point. Given more greatly deflected beams whose exciters are at a greater distance from the focal point, the gain in such an antenna decreases as the side lobes increase, limiting the elevation angle range. A single parabolic cylinder reflector generating a beam and focusing only in the horizontal plane is employed as the reflector, the individual radiators of a primary radiator row being arranged along its focal line.

Abstract: An omni-directional type passive antenna in which the response pattern is a close approach to the ideal of a hemisphere. The system includes an antenna having an antenna axis extending in the direction of highest antenna sensitivity, and a first surface which is a surface of revolution swept out by a part of a parabolic curve rotated about the antenna axis, the axis of the parabolic curve being inclined at an angle in the range of about 70 to 80 degrees to the antenna axis with the focus of the parabolic curve substantially on the antenna axis. A first set of electrically isolated dipoles is mounted on the surface and all are similarly oriented such that they lie only along edges of axial planes of the antenna.

Abstract: A radio frequency antenna having a parabolic reflecting surface and an array of feeds disposed adjacent the focal point of the parabolic reflecting surface, such feeds providing a predetermined amplitude and phase distribution to radio frequency signals passing to such feeds, each one of such feeds passing such energy in the same propagation mode. The energy passing through each one of the feeds is reflected from the reflecting surface and combines at the radiating aperture to provide, in free space, an antenna pattern having relatively low sidelobes over a relatively wide band of frequencies. The array of feeds includes a waveguide section having opposing outer wall portions and a plurality of conductive members disposed between the opposing outer wall portions to provide, with the outer wall portions, a plurality of channels.

Abstract: The disclosed common aperture seeker antenna includes a parabolic array of crossed dipoles. This array is substantially reflective for radiated electrical signals in one band, and substantially transmissive for radiated electrical signals outside of that band. A monopulse (four-element) waveguide feed is rigidly positioned on the concave side of the parabolic array at the focal point thereof. The parabolic reflector antenna operates in the one band to provide a high gain active system for accurate tracking of targets. A planar spiral antenna is rigidly positioned on the convex side of the parabolic array in axial alignment with the parabolic reflector antenna. This wideband antenna operates over a multioctave frequency band below that of the one band to provide a low gain system for passive tracking of targets. The two antenna systems coexist in such a manner that each utilizes the available aperture to its fullest extent.

Abstract: A microstrip backfire antenna which combines the microstrip type antenna ment with a backfire cavity to provide more than three times the gain over a single microstrip element and thereby be capable of replacing four or more elements of a conventional microstrip array. The microstrip backfire antenna consists of a microstrip element in a cavity between a total reflector and a partial reflector and is characterized by multiple reflections of electromagnetic waves between the two reflectors and by energy being radiated normal to and through the partial reflector.

Abstract: An improved directional antenna for microwave transmissions is disclosed comprising a paraboloidal main reflector, a waveguide feed having a first open end thereof positioned on the axis of the main reflector, and a second waveguide of the same size serially connected between the second open end of the waveguide feed and a transmission device such as a microwave transceiver. The waveguide feed has an elliptical cross-section throughout its axial length, thus providing an elliptically shaped first open end that in of itself and without separate horn attachment, functions as a feed energizer; while the second waveguide also has an elliptical cross-section of the same size, which in combination with such waveguide feed provides a microwave coupling to the transmission device that minimizes reflections, respectively matching problems, especially in the case of overmoded waveguide applications.

Abstract: The antenna system employs a parabolic reflector fed by an offset feed array of circular wave guides located substantially at the focus of the parabolic reflector, but offset from the axis thereof. A plurality of aperture tuning mechanisms disposed at the mouths of the circular waveguides of the waveguide feed array, and having physical lengths much shorter than one wavelength at the frequencies involved, are provided to reduce cross-polarization and mutual coupling between adjacent feeds. The short resonant length of these tuning mechanisms, and their shape which is chosen to generate the TM.sub.11 mode E-field contour line ensures that they are effective over a broad bandwidth of as much as 20% or more. Within this bandwidth, they act as inductive suppressors to control both cross-polarization and mutual coupling between adjacent feeds.

Abstract: An antenna system is disclosed comprising a paraboloidal reflector and a feed array having several substantially identical feed elements. The antenna produces a coverage pattern of transmitted radiation in the form of a shaped beam. The present invention permits the use of a smaller number of feed elements for a given size of the reflector's aperture by means of attenuating the sinusoidal ripple that is present in the shaped beam radiation pattern and caused by the size of the feed elements. A plurality of disks is placed in the focal plane of the paraboloidal reflector. The disks are selective with respect to one spatial frequency of the emitted radiation (which is at a constant electromagnetic frequency). The disks may be fabricated of a material which reflects the radiation, a material which absorbs the radiation, or a dielectric material of a certain thickness stipulated herein which changes the phase of the radiation by 90.degree..

Abstract: Disclosed is a conically scanning antenna emitting a beam of radiation which is modulated in phase but not in amplitude. In certain embodiments the antenna comprises a source of radiation including a horn illuminating a reflector, the horn being either inclined to the reflector axis or juxtaposed with a prism imparting such inclination to its direction of maximum radiation. The inclined horn or the prism is rotated about the axis by drive means supplying a reference scanning signal to a processor.

Abstract: A triple-beam offset paraboloidal antenna minimizes the offset of each of ree antenna feeds from the focal point of the paraboloid to thereby minimize beam aberrations, while at the same time maximizing the beam steering capability of the antenna. Three beams are produced, two being in mutually orthogonal planes. The axis of the third beam corresponds to the intersection of the orthogonal planes. The antenna in accordance with the present invention finds particular utility in the measurement of three dimensional wind profiles employing doppler radar techniques.

Abstract: An integrated radar antenna array consists of a first antenna, in which an exciter is positioned at a focal length of a double curvature reflector with different height and width dimensions to generate a first directional radiation pattern, and a second antenna comprising the reflector of the first antenna and a plurality of micro strip surfaces fitted to the double curvature of the reflector and suitably secured thereon.The radiating micro strip surface is positioned on the reflector at a distance d=K.lambda./2 where .lambda.=wavelength of the exciter frequency and K can be 0,1,2,3 . . . n.

Abstract: The invention relates to a printed monopulse primary source for a radar antenna.The primary source has, arranged on a first face of a dielectric material substrate, radiating zones forming independent site and bearing difference and sum channels. A receiving supply circuit for the radiating zones is arranged on a second face of the substrate, opposite to the first face. Connecting means ensure the electrical connection of the radiating zones to the receiving supply circuit in the thickness of the substrate.Application to airport radar systems.

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: A collapsible dish structure composed of a plurality of rows of rigid radial petal assemblies concentric with the axis of the dish. The petal assemblies consist of a center petal and two side petals, the center petal hinged on an axis tangent to a circle concentric with the axis of the dish and the side petals hinged to the center petal at their mating edge. The center petal is foldable inwardly and the side petals rotate about their hinges such that the collapsed dish structure occupies a much smaller volume than the deployed dish. Means of controlling the shape of the dish to compensate for differential expansion of the deployed dish are also provided.

Abstract: A parallel-plane antenna of the pillbox or cheese type in which the cylindrical-parabolic portion is constituted by a semitransparent reflector and the focal plane of which is constituted by a polarizing reflector. The cylindrical-parabolic semitransparent reflector is constituted by an array of wires parallel to the plane of polarization of the wave emitted by the source. The polarizing reflector is formed by a reflecting plate located at a distance of .lambda./4 from an array of parallel wires inclined at 45.degree. with respect to the plane of polarization of the incident wave.

Abstract: A modified parabolic antenna exhibiting low wind load characteristics having a collapsible reflector boom and a plurality of reflector elements mounted thereon. The collapsible boom includes two symmetrical parabolically shaped half sections. A first and second series of thin substantially elongated rectangular shaped reflector elements are mounted to each boom in a predetermined spaced relationship. Each reflector element is identical to the other and is also parabolically curved.

Abstract: A bifunctional antenna of a primary/secondary radar system comprises a reflector having a concave front surface formed with a row of slots along a horizontal generatrix, the slots lying in front of respective cavities excitable to radiate interrogation signals in a directive sum pattern and supplemental radiation in a differential control pattern designed to blank minor lobes of the interrogation pattern. Some of the cavities and slots are symmetrically duplicated on a dielectric cap covering the convex rear surface of the reflector. The reflector and its cap form a closed shell of dielectric material, specifically a glass mat impregnated with epoxy resin, overlain at the front by a fiber-glass fabric incorporating orthogonally intersecting insulated copper wires.

Abstract: This specification discloses a frontal reflector bracing wherein at least a portion of the support for a reflecting surface is positioned on the front side of the surface and the rearward most support is adjacent the reflecting surface. A natural structural rigidity minimizing weight can be achieved with a frontal truss arrangement including radial components.

Abstract: A system for, and a method of, scanning a collimated beam of electromagnetic radiation with a very large primary reflector of an antenna system without loss (i.e., with zero phase error) and without moving the primary reflector. The system is a two dimensional scan, loss-free, Cassegrain antenna system which comprises a stationary, parabolic-shaped, primary reflector, and a smaller, movable, parabolic-shaped subreflector, and also a movable, plane wave, electromagnetic radiation beam source interposed between the two reflectors. It is shown that, without moving the primary reflector, the beam can be scanned over wide angles with no phase error in the plane of scan, provided that the source and the subreflector are rotated about the focal point of the antenna in a specific manner. A unique angular relationship between the source and the subreflector is required for each scan angle, and is taught.

Abstract: A conical scan microwave antenna having a stationary fixed axially symmetric primary reflector consisting of any concave surface of revolution along with a spherical wave point source feed-and-subreflector assembly potentially rotatable about the axis of the primary reflector, and with the surface of the subreflecror being shaped so that the reflection of the spherical wave from the feed and off of the subreflector strikes the primary antenna and is reflected as a co-planar wavefront from every point on the primary reflector, and, further, the subreflector-and-feed assembly is located outside of the aperture of the reflected pencil beam such that for any given scan position of the subreflector, no portion of the reflected wavefront intersects the subreflector or its feed.

Abstract: A cylindrical metal sheath surrounds the beam rays between the antenna and the passive reflector of a periscope arrangement; this sheath forms the support of the periscope arrangement as well as a screen against parasitic radiation.

Abstract: An antenna structure, kit and method for making the structure comprising a generally circular base, a plurality of specially formed pre-stressed similarly shaped and sized arms which may be affixed in a disk array to the base and means, an arm encircling turnbuckel cable arrangement, for stressing the pre-stressed arms into a generally parabolic disk array is disclosed. The ribs are each made of a plurality of layers of resilient material, such as wood, which are bonded together in a bowed pre-stressed shape, which shape when modified by the stressing by the cable to assume a generally parabolic disk.