Abstract: A multi band antenna feed, for supporting multiple frequency bands, is coupled to a reflector and includes a cylindrical core waveguide and at least three coaxial cylinders, encircling said cylindrical core waveguide and forming at least three coaxial waveguides, bounded between pairs of consecutive coaxial cylinders. The cylindrical core waveguide and the at least three coaxial waveguides provide a pair of sum and difference radiation patterns, for each frequency band: a C-band, an S-band and an L-band.

Abstract: A method and system are disclosed for wide angle multibeam antennas. The method and system involve a multibeam antenna system for generating high performance multiple spot beams. In one or more embodiments, the multibeam antenna system includes an oversized antenna reflector and a plurality of antenna feeds. The oversized antenna reflector has its surface shape optimized from a normal parabolic shape in order to broaden and shape the reflected spot beams to improve antenna performance. In addition, the diameter of the oversized antenna reflector is greater than ((100*?)/?), where ? is the wavelength in inches and ? is the beam to beam spacing in degrees. In some embodiments, the ratio of the focal length of the oversized antenna reflector to the diameter of the oversized antenna reflector (F/D) is greater than 0.7. In at least one embodiment, the system further includes an antenna sub-reflector.

Abstract: A coupling device for transmitting a wireless signal is provided. The coupling device includes a substrate, a ground layer and a feed conductor. The substrate includes a first surface and a second surface opposite to the first surface. The ground layer is disposed on the second surface having a circular opening, and the circular opening has an opening edge and an opening center. The feed conductor extends on the first surface, including a conductive portion and a feed portion connected thereto. The feed portion corresponds to the circular opening, wherein the opening center is on a base line, a radial line is formed between the opening center and the opening edge, a radial distance is formed on the radial line between the opening edge and the feed portion, and a length of the radial distance varies with an angle between the radial line and the base line.

Abstract: Methods, systems, and apparatuses for receiving signals from communications satellites are disclosed.

Abstract: An antenna feed assembly is provided which includes at least two elongate feed chains lying adjacent one another. Each feed chain is adapted to transmit or receive electromagnetic radiation between itself and the antenna along a longitudinal feed axis thereof via a transmit/receive element. The feed chains are held in fixed lateral relationship to one another by first and second mountings spaced apart axially of the feed chains. The transmit/receive elements extend axially from the first mounting towards the antenna and the second mounting is positioned on a side of the first mounting remote from the antenna. The first mounting has a lower coefficient of thermal expansion in the lateral direction than the second mounting whereby translational movement of each transmit/receive element in the lateral direction owing to temperature change of the assembly will be reduced.

Abstract: The present invention provides an improved single antenna system that allows reception of RF energy at multiple frequencies. In one embodiment, the antenna is implemented as a multi-beam, multi-feed antenna having a primary reflector fitted with a dual mode feed tube and a switchable LNB that supports both Ka band and Ku band reception. In another embodiment, the antenna is implemented as a multi-beam, multi-feed antenna having a primary reflector fitted with a feed horn and a LNB that is capable of providing movement such that the feed horn with the LNB is at a focal point with the primary reflector for both Ka and Ku band reception. In another embodiment, the antennae is implemented as a multi-beam, multi-feed antenna having a primary reflected fitted with a feed horn assembly and a switchable LNB that supports both Ka band and Ku band reception.

Abstract: An antenna system includes a reflector having a modified-paraboloid shape; and a multi-beam, multi-band feed array located at a focal point of the reflector so that the antenna system forms a multiple congruent beams that are contiguous. The system has a single reflector with non-frequency selective surface. The reflector is sized to produce a required beam size at K-band frequencies and is oversized at EHF-band frequencies. The synthesized reflector surface is moderately shaped and disproportionately broadens EHF-band and Ka-band beams compared to K-band beams. The synthesized reflector surface forms multiple beams each having a 0.5-degree diameter at K-band, Ka-band, and EHF band. The multi-beam, multi-band feed array includes a number of high-efficiency, multi-mode circular horns that operate in focused mode at K-band and defocused mode at Ka-band and EHF-band by employing “frequency-dependent” design for the horns.

Abstract: The present invention provides an improved antenna system on moving platform that is in communication with multiple satellites for simultaneous reception and transmission of RF energy at multiple frequencies. The antenna is implemented as a multi-beam, multi-band antenna having a main reflector with multiple feed horns and a sub-reflector having a reflective surface defining an image focus for a Ka band frequency signal and a prime focus for a Ku band frequency signal.

Abstract: A feed assembly for a parabolic dish reflector is described. The feed assembly includes a waveguide cavity locatable at the focal point, or any other desired off-boresight location corresponding point, of the parabolic dish, at least one first radiating element optimized for operation at a first frequency band and provided on a top surface of the waveguide cavity, and a plurality of second radiating elements each optimized for operation at a second band of frequencies and provided on the top surface of the waveguide cavity.

Abstract: An antenna system for transmitting and/or receiving radio frequency (RF) signals in multiple frequency bands includes a horn antenna and a feed network. The horn antenna may transmit and/or receive RF signals in multiple frequency bands that are spread over more than an octave bandwidth with at least a 2.44-to-1 bandwidth ratio. The horn antenna includes a throat, an aperture, and an interior surface. The feed network includes a first waveguide section, a first junction, one or more first filters, and a first step-down waveguide section. The first waveguide section can provide a matching network and transmit and/or receive the RF signals in the multiple frequency bands. The first junction can transmit and/or receive the RF signals in first selected band(s) of the multiple frequency bands. The first step-down waveguide section may transmit and/or receive the RF signals in second selected band(s) of the multiple frequency bands.

Abstract: An array antenna with reflector(s) (AR) comprises i) an array (RS) of at least two feeds (S1-S5), including a central feed (S1), arranged and positioned so as to transmit and/or receive beams (F1-F5) in chosen directions, ii) beam-forming means responsible for controlling the amplitude and phase of each of the feeds by means of amplitude/phase laws applied to their ports and providing an appropriate amplification level, in order for each feed (S1-S5) to transmit a chosen radiation pattern (forming a beam and comprising a main lobe) intended to cover a chosen zone (Z1-Z5), and iii) at least one reflector (RC) provided with a surface (SU) specifically for reflecting the beams delivered by the feeds and/or intended for the latter, and shaped tree-dimensionally so as to reflect the beam delivered by each feed (S1-S5) by spreading its energy such that it covers the chosen associated zone, that the main lobe of the radiation pattern associated with the central feed (S1) defines a primary coverage (CP) fully includi

Abstract: An antenna system for generating and configuring at least one defocused beam is provided. The antenna system includes a reflector having a focal plane and a non-parabolic curvature for forming the at least one defocused beam, and a plurality of feed antennas that illuminate the reflector. Each feed antenna is disposed in the focal plane of the reflector. The antenna system further includes at least one incoming signal dividing network that divides at least one incoming signal into a plurality of sub-signals, each corresponding to one of the feed antennas, a plurality of variable phase shifters, each receiving one of the sub-signals from the incoming signal dividing network and phase shifting the sub-signal to generate a corresponding phase-shifted sub-signal, and a plurality of fixed-amplitude amplifiers, at least one corresponding to each of the feed antennas.

Abstract: Contamination at the exciter of a parabolic antenna can lead to impaired signal quality, or even system downtime. A parabolic antenna is described which in addition to a parabolic reflector and an exciter has a rinsing device, which is configured so as to rinse and clean the exciter with rinsing agent or protect it from contaminants. Herein, the rinsing agent is injected, dropped, or else blown from a rinsing outlet in an outlet member at the parabolic reflector onto the exciter. Mounting the rinsing outlet directly to the parabolic reflector allows for the exciter to be cleaned from the parabolic reflector.

Abstract: There is disclosed an LNB alignment device having a main body that removably attaches to a support arm of a satellite dish and has a plurality of mounting holes or rectangular sleeves configured to receive a plurality of low-noise block converters with feed horns (LNBs). The proximal and distal ends of the bar curve inwardly toward the satellite dish and curve slightly upward in a manner that the feed horns of LNBs outside of the focal axis are disposed higher and closer to the center of the reflector to improve signal quality.

Abstract: An antenna system for transmitting and/or receiving radio frequency (RF) signals in multiple frequency bands includes a horn antenna and a feed network. The horn antenna may transmit and/or receive RF signals in multiple frequency bands that are spread over more than an octave bandwidth with at least a 2.44-to-1 bandwidth ratio. The horn antenna includes a throat, an aperture, and an interior surface. The feed network includes a first waveguide section, a first junction, one or more first filters, and a first step-down waveguide section. The first waveguide section can provide a matching network and transmit and/or receive the RF signals in the multiple frequency bands. The first junction can transmit and/or receive the RF signals in first selected band(s) of the multiple frequency bands. The first step-down waveguide section may transmit and/or receive the RF signals in second selected band(s) of the multiple frequency bands.

Abstract: A feed assembly (26) for an antenna system (38) includes a first feed element (30) that propagates a first beam (32) and a second feed element (34) that propagates a second beam (36). The second feed element (34) is collocated with, but displaced vertically from, the first feed element (30) to achieve angular diversity in elevation. Each of the feed elements (30, 34) has an elongated conical shape and is formed from a dielectric material. The feed assembly (26) operates within the Ku-band frequency range to yield high gain, collimated, independent first and second beams (32, 36). The feed assembly (26) can be implemented in a tropospheric scatter communication system (38) in conjunction with a reflector (22) to provide concurrent transmit and receive capability via the two independent, angularly separated first and second beams (32, 36).

Abstract: Reflections on the aerial system of a fill level radar result in reduced measuring quality at short range. Small echo signals at short range can thus disappear in the noise. According to one embodiment of the present invention a parabolic aerial for a fill level radar is stated, which parabolic aerial comprises a parabolic mirror, an exciter and a diffusion disc. The diffusion disc is used for laterally removing interfering electromagnetic waves that would otherwise be absorbed by the exciter. In this way the decay behaviour at short range can be reduced.

Abstract: A antenna system for generating and distributing power among a plurality of non-focused beams is provided The system comprises a reflector having a focal plane and a non-parabolic curvature configured to form the defocused beams. The curvature is configured to create a symmetrical quadratic phase-front in an aperture plane of the reflector. The system further comprises a plurality of feed antennas disposed in the focal plane of the reflector and configured to illuminate the reflector. Each feed antenna is configured to contribute power toward each of the defocused beams. The system further comprises a plurality of fixed-amplitude amplifiers, at least one of which corresponds to each feed antenna.

Abstract: Embodiments of wireless antenna array systems to achieve three-dimensional beam coverage are described herein. Other embodiments may be described and claimed.

Abstract: The invention concerns an antenna system for level measurement with a level measurement device with a wave guide (5) that runs axially and that either has on its rear side an arrangement (4) for the generating and interpreting electromagnetic waves or can be connected to such an arrangement of an antenna, in particular, a parabolic antenna (1-3) on the front side of the wave guide and a wave adapter (9) for transmitting such a wave between two components of the arrangement that conduct the wave for adaptation of the wave transmission between the components, whereby the wave adapter has a through opening in the axial direction.

Abstract: A multi-beam-reflector dish antenna system and a method for production thereof are disclosed. Signals from different satellites are simultaneously received using a single compound LNBF module. The multi-beam-reflector dish antenna system includes a reflector with N-th order projected aperture and a single compound LNBF module constituting multiple LNBF units. The reflector is formed by projected aperture cutting and surface distortion of the aperture in accordance with the method of analysis and synthesis. In addition to reflecting signals from satellites, it also generates focused waves sharing similar radiation patterns and horizontal gain with incoming waves on the focal plane to be received by the compound LNBF modules.

Abstract: A reflective antenna is provided according to one or more embodiments of the invention. In one embodiment, the reflective antenna may include a feedhorn arrangement configured for an operation frequency. According to another embodiment, the reflective antenna may include a curved reflective surface having a plurality of electromagnetically loading structures. The curved reflective surface may be configured to reflect incident electromagnetic energy to corresponding to the operation frequency relative to at least one focal point. In another embodiment, the reflective antenna may include a support structure configured to arrange the feedhorn arrangement and the curved reflective surface such that the antenna assembly may be configured to provide multiple electromagnetic beams exhibiting high gain relative to the at least one focal point.

Abstract: The present invention is applicable to satellite ground station antennas having a wide field of view in comparison to the satellites with which the antenna connects. One embodiment includes a parabolic reflector having a size that corresponds to a beam with an angular half-width larger than the spacing between neighboring interfering satellites. It also has a feed comprising at least two dielectric rod-based surface waveguides coupled to the parabolic reflector configured to have a high sensitivity for a target satellite within the angular half-width of the reflector beam and a low sensitivity for neighboring interfering satellites within the angular half-width of the reflector beam.

Abstract: An antenna capable of generating multiple beams that are close together and have side lobes of low level includes optics comprising a single main reflector and a set of primary sources, each source suitable for generating a beam taken up by the optics that transmits it, or suitable for receiving a beam picked up by the optics of the antenna. The main reflector has an aperture of diameter D as a function of the center wavelength of the frequency band of the beams and the half-power beam width of the beams coming from the main antenna element, and a dimensionless number lying in the range 1.5 to 4. The optics present a profile that is modified relative to conventional optics comprising a parabolic main reflector by a correction that imparts an amplitude and phase distribution that is preferably circularly symmetrical, and compliant with a relationship for enlarging the reflected beams.

Abstract: The present invention is applicable to satellite ground station antennas having a wide field of view in comparison to the satellites with which the antenna connects. One embodiment includes a parabolic reflector having a size that corresponds to a beam with an angular half-width larger than the spacing between neighboring interfering satellites. It also has a feed coupled to the parabolic reflector configured to have a high sensitivity for a target satellite within the angular half-width of the reflector beam and a low sensitivity for neighboring interfering satellites within the angular half-width of the reflector beam. Another embodiment includes projecting a first radiation pattern, such as a digital communications link, between a ground station antenna and a target satellite and projecting a second radiation pattern to a target interferer.

Abstract: A method and apparatus for receiving signals transmitted from a plurality of communications satellites. An apparatus in accordance with the present invention comprises a reflecting surface having a focal point, and a plurality of low noise block down converters with feedhorns (LNBFs), each LNBF having a boresight, wherein at least a first LNBF receives signals in a first frequency band transmitted from a first communication satellite location that are focused at a first focal point and at least a second LNBF receives signals in a second frequency band transmitted from a second satellite location that are focused at a second focal point, wherein the boresight of the first LNBF is closer to the first focal point than the boresight of the second LNBF is to the second focal point.

Abstract: A multiple-beam antenna system includes at least one reflector and a cluster of horns for feeding the reflector. A horn of the cluster of horns is configured for providing transmission and reception of signals over respective transmission and reception frequency bands. The horn includes a substantially conical wall having an internal surface with a variable slope. The internal surface of the substantially conical wall includes slope discontinuities. At least one of the slope discontinuities has a diameter greater than 1.7 times the wavelength of the lowest frequency of the transmission frequency band. The diameter is also greater than 1.7 times the wavelength of the highest frequency of the transmission frequency band. In addition, the diameter is greater than 1.7 times the wavelength of the lowest frequency of the reception frequency band, and the diameter is greater than 1.7 times the wavelength of the highest frequency of the reception frequency band.

Abstract: An antenna system includes a reflector having a modified-paraboloid shape; and a multi-beam, multi-band feed array located at a focal point of the reflector so that the antenna system forms a multiple congruent beams that are contiguous. The system has a single reflector with non-frequency selective surface. The reflector is sized to produce a required beam size at K-band frequencies and is oversized at EHF-band frequencies. The synthesized reflector surface is moderately shaped and disproportionately broadens EHF-band and Ka-band beams compared to K-band beams. The synthesized reflector surface forms multiple beams each having a 0.5-degree diameter at K-band, Ka-band, and EHF band. The multi-beam, multi-band feed array includes a number of high-efficiency, multi-mode circular horns that operate in focused mode at K-band and defocused mode at Ka-band and EHF-band by employing “frequency-dependent” design for the horns.

Abstract: A antenna made from a photonic band-gap (PBG) material, includes: a lateral wall (4) which is made from a PBG material and which completely surrounds a central axis (6), the wall being disposed at a distance from the central axis such as to form a central resonant cavity; and at least one radiating element (34) which is placed inside the cavity. Each radiating element is positioned inside the cavity in order to excite an electromagnetic field parallel to the central axis and the radiating element(s) can excite the modes of the central cavity having a radial resonance more strongly than the other modes of the cavity.

Abstract: A feed window for a low noise block converter feedhorn incorporated into a microwave-range antenna assembly is formed from a thermoplastic polymer composition containing a hydroscopic-effective amount of a high molecular weight siloxane.

Abstract: The present invention provides a parabolic dish reflector antenna for wireless communications that is dually polarized for diversity reception purposes while causing minimal visual disturbance for use with cellular base stations and repeaters. The antenna comprises a reflector of paraboloidal shape along both the longitudinal and latitudinal axes of its diameter. The reflector of the antenna is comprised of 4 identical quadrants assembled at the installation site, where each quadrant is made of thin metal ribs with large openings metal mesh stretched and attached to the ribs. The antenna further comprises a feed that is located around the focal point. The antenna feed comprises an open cup-shaped conductive cavity wherein the two orthogonally mounted feeding elements of the antenna located within its volume, are low cost printed circuit board elements.

Abstract: Integrating dual antennae into a single rigid assembly guarantees parallel alignment between the antennae and provides higher isolation with lower insertion loss than duplexing methods can achieve through a single antenna. The resulting higher performance at lower cost can benefit two-way communication systems using time division duplexing, frequency division duplexing, or polarization division duplexing; or combinations of these methods.

Abstract: An antenna capable of generating multiple beams that are close together and have side lobes of low level includes optics comprising a single main reflector and a set of primary sources, each source suitable for generating a beam taken up by the optics that transmits it, or suitable for receiving a beam picked up by the optics of the antenna. The main reflector has an aperture of diameter D as a function of the center wavelength of the frequency band of the beams and the half-power beam width of the beams coming from the main antenna element, and a dimensionless number lying in the range 1.5 to 4. The optics present a profile that is modified relative to conventional optics comprising a parabolic main reflector by a correction that imparts an amplitude and phase distribution that is preferably circularly symmetrical, and compliant with a relationship for enlarging the reflected beams.

Abstract: This invention concerns a parabolic antenna with a parabolic reflector (2) having a parabolic reflector rim (20), a collar (9), which is positioned on the parabolic reflector (2), in particular on the parabolic reflector rim (20) and which has an outside collar rim (90), and having an exciter and/or a receiver (3), such that the exciter and/or receiver (3) are/is located in the axial direction (X) partly within the parabolic reflector rim (20) and partly outside thereof.

Abstract: A high power dual band high gain antenna system is provided. The antenna system employs one or more feedhorn clusters to distribute power associated with the transmission of high power signals. A first feedhorn cluster is associated with a first frequency band and a second feedhorn cluster is associated with a second frequency band that operates in frequencies below the first frequency band. The antenna system includes a sub-reflector and a main reflector with a first focal point of the sub-reflector being substantially aligned with a focal point of the main reflector. The first feedhorn cluster and the second feedhorn cluster are arranged on a surface of the main reflector with radiating aperture phase centers substantially aligned with a second focal point of the sub-reflector.

Abstract: An antenna system includes an antenna feed aligned with a subreflector and a main reflector. The subreflector has a concave surface defining a vertex. A main reflector having a concave surface is aligned with the subreflector to define an antenna focal area at the vertex of the subreflector. The antenna feed may be a phased array or fixed antenna feed. The antenna system may further include a controller cooperating with the phased array antenna feed for beamsteering or beamforming. The controller may cooperate with the phased array antenna feed to define and steer multiple beams, at different frequencies, for example.

Abstract: A multibeam primary radiator apparatus (2) includes first, second and third primary horns (16, 18, 20). The first primary horn (16) has a generally circular proximal end aperture (22) at its proximal end, and a generally circular distal end aperture (24) at its distal end, which is larger than the proximal end aperture (22). The second and third primary horns (18, 20) have generally circular proximal end apertures (26, 28) at their proximal ends, and larger distal end apertures (30, 32) at their distal ends. The first through third primary horns are disposed with the center axes of the respective proximal end apertures being substantially in parallel with each other. The distance between the center axis of the first primary horn (16) and each of the second and third primary horns (18, 20) is smaller than the diameter of the proximal end aperture (22) of the first primary horn (16).

Abstract: A method and apparatus for receiving signals transmitted from a plurality of communications satellites. An apparatus in accordance with the present invention comprises a reflecting surface having a focal point, and a plurality of low noise block down converters with feedhorns (LNBFs), each LNBF having a boresight, wherein at least a first LNBF receives signals in a first frequency band transmitted from a first communication satellite location that are focused at a first focal point and at least a second LNBF receives signals in a second frequency band transmitted from a second satellite location that are focused at a second focal point, wherein the boresight of the first LNBF is closer to the first focal point than the boresight of the second LNBF is to the second focal point.

Abstract: A device for modifying electromagnetic illumination of a reflector aperture defined by a reflector surface is mounted in front of the reflector aperture in a spaced apart relationship relative to the reflector surface. The device at least partially covers the reflector aperture and provides an illumination control means for at least partially and selectively modifying electromagnetic illumination of the reflector aperture. The device may include a membrane-like substrate that is substantially transparent to electromagnetic radiation. A supporting member may support the substrate in the spaced apart relationship relative to the reflector surface.

Abstract: A triple-band offset hybrid antenna having a shaped reflector is disclosed. The triple-band offset hybrid antenna includes: a shaped reflector reflecting a K/Ku bands RF signals received from a satellite to focus an energy of the K/Ku band RF signals on a focal line and reflecting a Ka band RF transmitting signal; and a triple-band active phased feed array receiving the reflected K/Ku bands RF signals from the shaped reflector and radiating the Ka band RF transmitting signal to the shaped reflector, wherein the triple-active feed array including Ka/K bands feed array for transceiving Ka/K bands RF signal and a Ku band feed array for receiving a Ku band RF signal.

Abstract: A Ka-band offset hybrid antenna having a shaped focuser is disclosed. The Ka-band offset hybrid antenna having a shaped focuser, including: a shaped focuser for reflecting a received plane wave to focus an energy of the received plane wave on an offset focal line and reflecting a transmitting signal; and an active feed array module for receiving the reflected received plane wave from the shaped focuser and radiating the transmitting signal to the shaped focuser antenna, wherein the active feed array module including a feed horn array antenna having a plurality of single horns and an active channel block (ACB) having multi-active channels for changing a direction angle of transceiving beam.

Abstract: A multi-beam-reflector dish antenna system. Signals from different satellites are simultaneously received using a single compound LNBF module. The antenna dish includes a reflector with N-th order projected aperture and a single compound LNBF module constituting multiple LNBF units. The reflector is formed by projected aperture cutting and surface distortion of the aperture in accordance with the method of analysis and synthesis. In addition to reflecting signals from satellites, it also generates focused waves sharing similar radiation patterns and horizontal gain with incoming waves on the focal plane to be received by the compound LNBF modules.

Abstract: In one embodiment of the present invention, an offset folded reflector pair is optimized for scanning off boresight by enforcing the Abbe Sine condition using a least-error approximation. Coma and astigmatism compare favorably over single reflector system and Gregorian pairs over a moderate field of view. A folded-pair reflector system of the present invention offers good performance in a compact size.

Abstract: An electronic scanning radio direction finding system for accurate direction finding of radio frequency signals using singly or doubly flared cylindrical reflectors surrounded by a circular array of inwardly facing feed horns. The array is operated as a phased array to determine the direction of origin of received signals. The feed horns can also be used to transmit RF signals on very narrowly controlled beams with minimal side lobes. The flared cylindrical reflector and its circular feed horn array may be paired with circular log periodic arrays operable at similar frequency ranges or different frequency ranges to provide more precise direction finding and direction finding of signals at frequencies beyond the range of the flared cylindrical reflector and its circular feed horn array.

Abstract: A device for receiving/transmitting electromagnetic signals from/to at least two satellites fixedly located at points at the geostationary path comprises an antenna, for example a lens (1) of waveguide nature. The antenna images remote points at a focal surface and in the points where the satellites are imaged receiver horns (23, 23?) are placed. The horns are adjustably mounted to a rail (21) of a mounting unit (9) except the central horn (23?) that is fixedly placed for receiving along the optical axis of the antenna, at a predetermined distance of the antenna. The rail is mounted to be rotated about the optical axis of the antenna, this giving a simple adjustment of the other horns (23). Using an adjusting assembly the curvature of the rail can be varied to be adapted to receiving at different latitudes.

Abstract: A compact multi-band ring-focus antenna system. The antenna system includes a first and a second main reflector 304, 306, each having a shaped surface of revolution about a common boresight axis (322) of the antenna. A first backfire type RF feed system (302, 312) is provided for feeding the first main reflector (304) on a first frequency band. A second RF feed (301) coaxial with the first RF feed (300) is provided for feeding the second main reflector (306) on a second frequency band spectrally offset from the first frequency band. Further a portion of the second RF feed passes through a first sub-reflectors (302) of the backfire feed. The second RF feed is terminated a distance from the first sub-reflector to illuminate a second sub-reflector (303).

Abstract: Method and apparatus for feeding a compact main reflector of an RF antenna on a plurality of spectrally offset frequency bands. The method can include the steps of forming a focal ring for a main reflector (304) by positioning an RF source (301) at a first frequency within a first frequency band in the far field relative to a shaped non-linear surface of revolution so that the shaped non-linear surface of revolution forms a subreflector (302). A second focal ring can be formed for the main reflector (304) by positioning a second RF source (300) in the nearfield of the shaped non-linear surface of revolution.

Abstract: An electronic scanning radio direction finding system for accurate direction finding of radio frequency signals using singly or doubly flared cylindrical reflectors surrounded by a circular array of inwardly facing feed horns. The array is operated as a phased array to determine the direction of origin of received signals. The feed horns can also be used to transmit RF signals on very narrowly controlled beams with minimal side lobes. The flared cylindrical reflector and its circular feed horn array may be paired with circular log periodic arrays operable at similar frequency ranges or different frequency ranges to provide more precise direction finding and direction finding of signals at frequencies beyond the range of the flared cylindrical reflector and its circular feed horn array.

Abstract: A shield for shielding radio frequency emissions being emitted from a communications antenna. The shield has a first layer of material having the physical property of generally absorbing radio frequency electromagnetic emissions and a second layer of material having the physical property of generally reflecting radio frequency emissions. The first layer of material is positioned between the second layer of material and the communications antenna. Therefore, the first layer of material absorbs a portion of the radio frequency emissions from the communications antenna, and the second layer of material reflects back the remaining emissions to the first layer of material. Therefore, the first layer absorbs a further portion of the remaining emissions. A layer of absorbing material is placed between the combined first & second layers and a material that is transparent to radio frequency emissions and through which the communications antenna radiates radio frequency energy.

Abstract: The invention concerns the secondary reflectors of SHF antennae of the Cassegrain type.