Abstract: An antenna-shared distributor is provided such that a non-conductor section is provided in a part of two conductor planes, a dielectric resonator which resonates in the HE111 mode is disposed between the conductor planes, and first and second dielectric strips whose respective end portions face the dielectric resonator are disposed, forming first and second dielectric lines and further, a voltage-controlled oscillator and a mixer are connected to the first and second dielectric lines, respectively.

Abstract: An antenna includes a cylindrically shaped dielectric resonator placed on a longitudinally extended axis of an elongated dielectric strip disposed on a planar conductor and another planar conductor having an opening covers the dielectric strip with the opening on the dielectric resonator. There may be another dielectric strip placed perpendicularly to the first dielectric strip such that the dielectric resonator is where the lines longitudinally extended from the axes of both dielectric strips will cross.

Abstract: A single radiating structure with an integrated mode transducer that produces near-ideal radiation characteristics at two frequency bands. The dual band feed consists of three main sections: feed waveguide, mode transducer and corrugated horn. The feed waveguide consists of two concentric, circular waveguides that are excited in the TE.sub.11 coaxial and circular waveguide modes for the low and high bands, respectively. The mode transducer, which is critical to the performance of the feed, provides a single mode, low return loss transition, for both bands, between the feed waveguide and the corrugated horn. This is achieved by converting the TE.sub.11 circular waveguide modes into the fundamental hybrid, HE.sub.11, mode of the corrugated horn. The corrugated horn, which is a stepped-slot configuration, is designed to achieve a smooth transition from the mode transducer and to produce the desired radiation characteristics at both frequency bands.

Abstract: Systems and methods for scanning antennas with plasma gratings are described. An apparatus includes a semiconductor slab and an electrode set or illuminating system to inject a plasma grating. The systems and methods provide advantages in the compactness and higher efficiency in comparison with existing antennas.

Abstract: An antenna is provided in which electromagnetic signals in the High Frequy and Super High Frequency bands are propagated utilizing ionized gas, or plasma. Energized electrodes ionize the gas and the plasma is confined within non-metallic coaxial tubes contained within a non-metallic pressure vessel. Electric field gradients are used to change the shape and density of the plasma to affect the gain and directivity of the antenna. The inner plasma tube acts as the radiating source, while the outer plasma tube is used to change the radiation of the inner tube and to reflect the radiated signal. Instrumentation measures the density of the plasma providing a means to measure incoming signals as well as to regulate the radiation frequency.

Abstract: Systems and methods for thermal imagining are described. An apparatus includes a rotatable radial scanning antenna. The systems and methods provide advantages in that fires can be detected, and their positions determined, over substantial distances and through obscurants such as smoke and/or rain.

Abstract: A dielectric rod antenna has a dielectric rod and a waveguide which receives one end of the dielectric rod to excite the dielectric rod. The dielectric rod is divided along its length into at least two sections including a hollow tubular dielectric sleeve and a dielectric internal rod telescopically received and secured in the hollow of the dielectric sleeve. One end of the dielectric internal rod makes a releasable-fit engagement with the adjacent end of the dielectric sleeve so that the overall length of the antenna can be fixed against change during the use. The overall radius and the hollow radius of the dielectric sleeve and the overall radius of the dielectric internal rod are determined such that the propagation constant in the dielectric sleeve and the propagation constant in the dielectric internal rod are equalized to each other. The end of the dielectric internal rod adjacent to the dielectric sleeve is tapered so as to converge towards the end extremity.

Abstract: Systems and methods for two dimensional millimeter wave imaging are described. A system includes a spindle assembly defining a rotation axis; a waveguide assembly connected to the spindle assembly, the waveguide assembly including a first dielectric waveguide defining a first axis; and a grating assembly connected to the spindle assembly, the grating assembly including a plurality of sectors, each of the plurality of sectors including a varying period conductive grating pattern. A varying period of the varying period conductive grating pattern is a function of an angle defined by a rotational position of the grating assembly with regard to the rotation axis. The systems and methods provide advantages in that an image can be scanned quickly using an inexpensive system.

Abstract: First and second tandemly positioned electrically biased semiconductor members radiate microwave energy in response to the receipt of an excitation light beam having two wavelengths related to the bandgaps of the members. The projected microwave beam may be made more narrow and directional if two of the members are electrically biased at the same time. An inefficient frequency doubler generates the two wavelength beam enabling a single light beam to excite both members in a simple, rugged photoconductive antenna element.

Abstract: A feed system for an antenna has a set of inner and outer coaxial waveguides which apply, respectively, both higher and lower frequency radiations to a common radiating aperture provided by a horn and shroud which envelops radiating apertures of the individual feed waveguides. Each of the feed waveguides carries signals having a bandwidth of an octave. Lower frequency radiation to be transmitted by the outer coaxial feed waveguide is applied thereto by a set of four waveguides of a launcher which launches a wave with a desired propagation mode into the outer feed waveguide. Each of the launch waveguides is initially a rectangular double-ridged waveguide for increase bandwidth. The ridging is reduced to a condition of no ridging in the outer feed waveguide by a transition to a single inner ridge which terminates in a tapered star-shaped combination ridge within the outer feed waveguide.

Abstract: A vehicle radar safety apparatus employs a radar for detecting an object in front and/or to the rear and sides of a vehicle and for producing an indication of the distance and closing speed between the vehicle and the detected object. A signal processing unit sums the vehicle speed and the closing speed between the vehicle and detected object and compares the summed output with a signal corresponding to the distance between the vehicle and the detected object to provide an output to a display indicating the vehicle's capability of stopping prior to colliding with the detected object. The output from the signal processing unit is optionally applied to an accelerator and/or brake control circuit to automatically slow down the vehicle. A brake pedal override switch is connected to the accelerator and brake controls to override the accelerator and/or brake controls when the vehicle operator depresses the vehicle brake pedal.

Abstract: An ultrawideband transverse electromagnetic mode horn antenna for use at high voltages, comprises a pulse generator (1) and two transmission horns (12, 18) containing different dielectric media. The interface (30) between the dielectric media is configured so that a signal from the generator is incident on the interface at an angle substantially equal to the Brewster angle, thereby maintaining a good impedance match across the interface. A further advantage of the arrangement is that the TEM wavefront is preserved through the antenna section allowing operation at fast pulse risetime (less than 200 ps) for short duration (several ns) at high voltage.

Abstract: Systems and methods for guided wave antennas are described. Apparatus is disclosed comprising: a dielectric nonphotoconductive waveguide defining a principle axis; a grating carrier connected to the dielectric nonphotoconductive waveguide, the grating carrier i) including a photoconductive material and ii) defining a photoconductive axis that is substantially parallel to the principle axis; a spatial light modulator optically connected to the layer of photoconductive material; and a source of illumination optically connected to the spatial light modulator and the layer of photoconductive material.

Abstract: Horn antenna (10) produces an electromagnetic energy field and includes waveguide (12) for generating an electromagnetic field having an electric field (52, 54, 56) and magnetic field (58 and 60). Horn portion (14) expands the electric field (52, 54, 56) and magnetic field (50, 60), and produces therefrom an electromagnetic energy field (34) at radiating aperture (29) of horn portion (14). Dielectric portion (32) is positioned within horn portion (14) and includes a sheet (32) of dielectric material that has a relatively uniform thickness. The dielectric portion (32) is placed across horn portion (14) perpendicular to electric field (52, 54, 56) to yield cosinusoidal electromagnetic field (34) at radiating aperture (29).

Abstract: A method for adjusting the radiation direction of an antenna, which uses a plurality of uniformly spaced diffraction gratings formed in the waveguide of the antenna while adjusting the maximum radiation direction of radiation waves emerging from the diffraction gratings and varying the length of crystal lattices in the diffraction gratings, thereby achieving an improvement in the directivity of the radiation waves and an adjustment in the radiation direction of radiation waves. In accordance with this method, it is possible to vary the radiation direction of an electronic wave passing through the antenna by varying the interval of crystal lattices in a region where the diffraction gratings exist. Accordingly, it is possible to obtain a narrow beam width characteristic. The diffraction gratings are made of a piezo-electric material.

Abstract: An omnidirectional isotropic antenna employing a tubular waveguide 12, a dielectric insert 18 which includes a lens 20 and a depending stem 22. The lens 20 is an elliptoid generated by rotating an elliptoid form about the longitudinal axis 42 of the tubular waveguide 12 with its foci 40 aligned with the longitudinal axis 42 and its major axis 38 lying in a zone of rotation 43 intersecting the horizontal plane 44 that is normal to the axis 42 and containing the foci 40. The stem 22 has integrally formed a polarizing element 36, and an impedance to matching element 21. There is provided a passband filter 50 and a modified tubular waveguide 60 that provides node differences for the RF signals.

Abstract: A feed system for an antenna has a set of inner and outer coaxial waveguides which apply, respectively, both higher and lower frequency radiations to a common radiating aperture provided by a horn and shroud which envelops radiating apertures of the individual feed waveguides. Each of the feed waveguides carries signals having a bandwidth of an octave. Lower frequency radiation to be transmitted by the outer coaxial feed waveguide is applied thereto by a set of four waveguides of a launcher which launches a wave with a desired propagation mode into the outer feed waveguide. Each of the launch waveguides is initially a rectangular double-ridged waveguide for increase bandwidth. The ridging is reduced to a condition of no ridging in the outer feed waveguide by a transition to a single inner ridge which terminates in a tapered star-shaped combination ridge within the outer feed waveguide.

Abstract: An innovative nonradioactive dielectric waveguide (NRD guide). Protrusions are separately formed on a surface of a dielectric strip. Recesses corresponding to the protrusions are formed on a parallel conductive plate. The dielectric strip is set between top and bottom parallel conductive plates such that the small protrusions on the dielectric strip are fitted into the recesses on the bottom parallel conductive plate.

Abstract: A scanning antenna is disclosed including: a rotatable cylinder having an outer surface; a continuously, or steppingly, varying period conductive grating pattern of separated strips on the outer surface, the varying conductive grating pattern of separated strips defining a grating axis; and a first elongated dielectric waveguide defining a first waveguide axis, the first elongated dielectric waveguide being located proximally adjacent and alongside the varying conductive grating pattern of separated strips so as to evanescently couple electromagnetic signals with the first elongated dielectric waveguide. The scanning antenna provides advantages in that the gain is high.

Abstract: A feed system for an antenna has a set of inner and outer coaxial waveguides which apply, respectively, both higher and lower frequency radiations to a common radiating aperture provided by a horn and shroud which envelops radiating apertures of the individual feed waveguides. Each of the feed waveguides carries signals having a bandwidth of an octave. Lower frequency radiation to be transmitted by the outer coaxial feed waveguide is applied thereto by a set of four waveguides of a launcher which launches a wave with a desired propagation mode into the outer feed waveguide. Each of the launch waveguides is initially a rectangular double-ridged waveguide for increase bandwidth. The ridging is reduced to a condition of no ridging in the outer feed waveguide by a transition to a single inner ridge which terminates in a tapered star-shaped combination ridge within the outer feed waveguide.

Abstract: A feed system for an antenna has a set of inner and outer coaxial waveguides which apply, respectively, both higher and lower frequency radiations to a common radiating aperture provided by a horn and shroud which envelops radiating apertures of the individual feed waveguides. Each of the feed waveguides carries signals having a bandwidth of an octave. Lower frequency radiation to be transmitted by the outer coaxial feed waveguide is applied thereto by a set of four waveguides of a launcher which launches a wave with a desired propagation mode into the outer feed waveguide. Each of the launch waveguides is initially a rectangular double-ridged waveguide for increase bandwidth. The ridging is reduced to a condition of no ridging in the outer feed waveguide by a transition to a single inner ridge which terminates in a tapered star-shaped combination ridge within the outer feed waveguide.

Abstract: A leakage dielectric waveguide includes a housing made of plane-shaped electrical conductors located parallel to each other, and a dielectric strip for propagating a high-frequency wave between the parallel electrical conductors, wherein the dielectric strip is provided within the housing. The housing is arranged to be asymmetrical, thereby leaking and radiating a high-frequency wave propagating through the dielectric strip. The housing is preferably further composed of the plane-shaped parallel electrical conductors and a side wall. A plane antenna includes the above-mentioned leakage dielectric waveguide, and a projecting device for projecting the high-frequency wave toward a free space in response to a high-frequency wave being projected from the dielectric waveguide.

Abstract: An antenna for transmitting or receiving electromagnetic radiation along an axis comprises at least three layers 20a, 20b, 20c, 20d and 20e of dielectric material spaced from one another in a direction perpendicular to the axis. The outermost layers 20a and 20e are spaced from one another by at least half the wavelength of the electromagnetic radiation. The layers extend generally in the direction of the axis from a rear end to a front end of the layers. A transition portion 22 electromagnetically couples the layers 20a, 20b, 20c, 20d and 20e directly to a waveguide 21. A front end of the transition portion 22 is connected to the rear end of the layers 20a, 20b, 20c, 20d and 20e and has a dimension in the direction perpendicular to the axis substantially equal to the spacing between the outermost layers 20a, 20e at the rear end of the layers.

Abstract: A microstrip patch or slot radiating element is coupled to a dielectric rod antenna by way of a tapered tubular dielectric guide formed integrally with the rod. An array of radiating elements may be formed on a common substrate, and the dielectric guide/rod antennae may be arranged to direct the energy radiated from these elements to a secondary antenna element such as a lens or a dish.

Abstract: The present invention provides multidimensional stacked photonic band gap crystal structures improving the performance of current planar monolithic antennas and RF filters by forbidding radiation from coupling into the substrate thereby significantly enhancing radiation efficiency and bandwidth. This invention comprises a number of sub-crystals with each having at least two lattices disposed within a host material, each lattice having a plurality of dielectric pieces arranged and spaced from each other in a predetermined manner, the sub-crystals being stacked in a crystal structure to provide a photonic band gap forbidding electromagnetic radiation propagating over a specially designed frequency band gap, or stopband. Both two dimensional and multidimensional crystals are disclosed.

Abstract: A microwave antenna comprises a single moded metal waveguide tapering inwardly to a cutoff dimension near the distal end thereof. The antenna also comprises a first solid dielectric waveguide mounted coaxially within the distal end portion of the metal waveguide and tapering outwardly toward the inwardly tapering portion of the metal waveguide. The first dielectric waveguide extends beyond the distal end of the metal waveguide in the axial direction. The antenna also comprises a second dielectric waveguide surrounding the first dielectric waveguide beyond the distal end of the metal waveguide and having a dielectric constant lower than the dielectric constant of the first dielectric waveguide. A distal end portion of the first dielectric waveguide tapers inwardly toward the axis thereof, to launch signals propagating toward the distal end of the first dielectric waveguide into the second dielectric waveguide.

Abstract: A compact scanned antenna which includes a radiator, a rotatable tube and a line source. The radiator is formed by plating a shaped dielectric core. It generates an antenna beam at an output aperture in response to a microwave signal at an input port. The line source generates a radiation sheet which is directed across a signal plane to the input pot. The tube has a cylindrical wall which is positioned across the signal plane. As the tube rotates, refractive or diffractive transmission structures pass through the signal plane. The refractive structures include linear segments which refract the wavefront of the radiation sheet. Because the wavefront slope at the radiator's aperture is a function of the wavefront slope at its input port, the antenna beam is scanned. The linear contour segments have the same inclination but are not colinear. This arrangement reduces the thickness of the tube wall. Phase coherence is achieved by an appropriate radial spacing of adjacent ends of contour segments.

Abstract: A diverging shall antenna fed by a waveguide supplying TE.sub.11 mode is described. A dielectric rod partially contained within the waveguide converts the TE.sub.11 mode to a dominant or HE.sub.11 mode. The HE.sub.11 mode is controllably converted to second and third order modes in the diverging shell by discontinuities placed in predetermined locations in the diverging shell. The discontinuities generating the second mode are incorporated into the dielectric rod structure. Turning of the relative amplitude and phase of the second and third order modes relative to the HE.sub.11 mode is achieved by slideably positioning the dielectric rod. An alternative embodiment of the inventive device includes a reactive surface of the diverging shell.

Abstract: A pyramidal horn antenna that decreases ringing in radar systems that are placed against a solid volume of e.g. concrete or wood for finding an object in or behind the solid volume. The antenna includes a solid, pyramid-shaped dielectric, the pyramid shape including a rectangular base and four triangular sides that extend from the base to meet at the apex of the pyramid. Two conductive triangular plates overlay opposite ones of the four sides of the pyramid, each of the plates including an electrical connection for coupling the plate to a radar system. The pyramid-shaped dielectric has a dielectric constant that approximates the dielectric constant of the solid volume, and therefore provides an impedance match between the antenna and the solid volume.

Abstract: A single integrated antenna feed transmits and receives electromagnetic waves in the C, X, and Ku frequency bands. This antenna feed includes an inner metal tube which lies along a central axis, and an outer metal tube which surrounds and is coaxial with the inner metal tube. Through the inner tube, a passageway is provided which is sized to carry electromagnetic waves in the X-band and Ku-band, but reject electromagnetic waves in the C-band. Between the inner tube and the outer tube, another passageway is provided which is sized to carry electromagnetic waves in the C-band. An I/O port for the X and Ku-bands is provided by a first end of the inner tube, and an I/O port for the C-band is provided by a corresponding first end of the outer tube. This first end of the outer tube lies proximate to but not past the first end of the inner tube. A solid dielectric is inserted into and fills the first end of the inner tube; and, a hollow metal cone is attached to the first end of the outer tube.

Abstract: An antenna device for transmitting a short pulse duration signal of predetermined radio frequency that eliminates a trailing antenna resonance signal. The device includes a gas filled tube; a voltage source for developing an electrically conductive path along a length of the tube corresponding to a resonant wavelength multiple of the predetermined radio frequency; and a signal transmission source coupled to the tube for supplying a radio frequency signal to the conductive path for antenna transmission. A method for transmitting a short pulse signal without a trailing residual signal is also provided.

Abstract: A dielectric material is formed into a structure having two parallel broad surfaces with one or more raised integral portions extending transversely across at least one of the broad surfaces. The exterior is uniformly conductively coated resulting in a parallel plate waveguide having a continuous transverse stub element disposed adjacent one plate thereof. Purely reactive elements are formed by leaving the conductive coating on the terminus of the stub element, or by narrowing the terminus of the stub element. Radiating elements are formed when stub elements of moderate height are opened to free space. Radiating, coupling and/or reactive continuous transverse stub elements may be combined in a common parallel plate structure in order to form a variety of microwave, millimeter wave and quasi-optical components including integrated filters, couplers and antenna arrays.

Abstract: A scanning antenna is disclosed including: a rotatable cylinder having an outer surface; a varying period conductive grating pattern of separated strips on the outer surface, the varying conductive grating pattern of separated strips defining a grating axis; and a first elongated dielectric waveguide defining a first waveguide axis, the first elongated dielectric waveguide being located proximally adjacent and alongside the varying conductive grating pattern of separated strips so as to evanescently couple electromagnetic signals with the first elongated dielectric waveguide. The scanning antenna provides advantages in that the gain is high.

Abstract: A dielectric rod antenna including a dielectric rod, a ring-shaped conductive film provided on an outer peripheral surface of the dielectric rod, and a waveguide. The conductive film is provided on an outer peripheral surface portion of the dielectric rod which is inclined from a base end portion toward a forward end portion. The conductive film is arranged to intersect the waveguide so as to form a substantially V-shaped cross-sectional area.

Abstract: A compact microwave antenna suitable of printed-circuit fabrication is comprised of a non-radiating guided wave structure for supporting the propagation of captured surface-guided waves; a series of dipoles in proximity to the guided waves supported by the non-radiating guided wave structure, wherein such dipoles are excited by the guided waves, thereby generating a desired radiation field, wherein the dipoles are independent of electrical transmission lines, and wherein the length and spacing of the dipoles are selected to achieve a desired angle of radiation from the surface of the non-radiating guided wave structure and a desired radiation frequency; and excitation means, in communication with the non-radiating guided wave structure, for exciting the reactive medium with electromagnetic waves to generate the captured surface-guided waves.

Abstract: A dielectric material is formed into a structure having two parallel broad surfaces with one or more raised integral portions extending transversely across at least one of the broad surfaces. The exterior is uniformly conductively coated resulting in a parallel plate waveguide having a continuous transverse stub element disposed adjacent one plate thereof. Purely reactive elements are formed by leaving the conductive coating on the terminus of the stub element, or by narrowing the terminus of the stub element. Radiating elements are formed when stub elements of moderate height are opened to free space. Radiating, coupling and/or reactive continuous transverse stub elements may be combined in a common parallel plate structure in order to form a variety of microwave, millimeter wave and quasi-optical components including integrated filters, couplers and antenna arrays.

Abstract: The ferroelectric scanning RF antenna includes a ferroelectric material having conductors deposited thereon that are connected to an adjustable d.c. or a.c. voltage source. The scanning antenna is placed in an RF transmission line that includes appropriate input and output impedance matching devices such as quarter-wave transformers. The scanning section of the RF scanning antenna is constructed of two prismatic structures of a ferroelectric material. When the two prismatic structures are at the same zero bias voltage, then the RF energy passing through the antenna is not deflected and a boresight radiation pattern is obtained. Application of a bias voltage reduces the permittivity and the refractive index of the outer prismatic structure. The RF energy is refracted away from the normal at the interface between the prismatic surfaces and the radiation pattern is scanned in one direction. Application of a bias voltage reduces the permittivity and the refractive index of the inner prismatic structure.

Abstract: An improved microstrip patch antenna has a pair, for example, of dielectric overlay strips attached along the radiating edges of the patch where the patch is rectangular. By optimizing dimensions parameters and materials, the bandwidth of the patch is increased substantially as well as the amount of radiated energy.

Abstract: A dielectric material is formed into a structure having two parallel broad surfaces with one or more raised integral portions extending transversely across at least one of the broad surfaces. The exterior is uniformly conductively coated resulting in a parallel plate waveguide having a continuous transverse stub element disposed adjacent one plate thereof. Purely reactive elements are formed by leaving the conductive coating on the terminus of the stub element, or by narrowing the terminus of the stub element. Radiating elements are formed when stub elements of moderate height are opened to free space. Radiating, coupling and/or reactive continuous transverse stub elements may be combined in a common parallel plate structure in order to form a variety of microwave, millimeter wave and quasi-optical components including integrated filters, couplers and antenna arrays.

Abstract: A dielectric material is formed into a structure having two parallel broad surfaces with one or more raised integral portions extending transversely across at least one of the broad surfaces. The exterior is uniformly conductively coated resulting in a parallel plate waveguide having a continuous transverse stub element disposed adjacent one plate thereof. Purely reactive elements are formed by leaving the conductive coating on the terminus of the stub element, or by narrowing the terminus of the stub element. Radiating elements are formed when stub elements of moderate height are opened to free space. Radiating, coupling and/or reactive continuous transverse stub elements may be combined in a common parallel plate structure in order to form a variety of microwave, millimeter wave and quasi-optical components including integrated filters, couplers and antenna arrays.

Abstract: The widebeam antenna includes a tapered dielectric waveguide having a radiating end and an end for coupling electromagnetic energy into and out of the dielectric waveguide. A conducting sleeve surrounds the dielectric waveguide. A corrugated flange surrounds the sleeve near the radiating end of the waveguide and a dielectric ring also surrounds the radiating end of the waveguide. It is preferred that the dielectric ring have a dielectric constant in the range of 2.0 to 4.0. The structure of the invention provides substantially uniform hemispherical coverage for the transmission and reception of electromagnetic energy.

Abstract: An antenna has a dielectric slab with an inner surface and an outer surface. The inner surface is mounted on a metal backplate. A radiating spiral is located on the outer surface of the dielectric slab and has a pitch of one wavelength at the design frequency. A circular waveguide, for providing RF energy in the TM.sub.01 mode, passes through the metal backplate to terminate at the inner surface of the dielectric slab. A metal cap is located on outer surface of the dielectric slab coaxial with the circular waveguide and at the center of the spiral. The metal cap has a surface is sloped away from the outer dielectric surface and has one or more concentric choke grooves formed on the sloped surface. The grooves are one quarter wavelength deep at the design frequency.

Abstract: A structurally-embedded electronics assembly is disclosed and includes an outer skin member which is lightly loaded structurally, a primary load-carrying member positioned inboard from the outer skin member, a core member positioned between the primary load-carrying member and the outer skin member, an intermediate skin member positioned between the outer skin member and the core member and an electronics structure positioned between a predetermined two of the members or intermingled with a predetermined number of the members set forth above which are adjacent each other. In another embodiment, a thermally conductive baseplate member is positioned inboard from the primary load-carrying member. In another embodiment, a vibration damping member is positioned inboard from the primary load-carrying member.

Abstract: A dual band feed arrangement for a microwave antenna provides microwave communication in a lower band and in a substantially widened upper band to provide simultaneous microwave communication for three signals. One signal in the lower band propagates between the outer and inner conductors of a coaxial waveguide in the TE.sub.11 coaxial mode, and two signals in the upper band propagate in the inner conductor in TE.sub.11 circular waveguide mode. A combiner, having a conically shaped section with a plurality of irises through its sidewall, is coupled to the coaxial waveguide to provide a transformation from the TE.sub.11 modes to the HE.sub.11 waveguide modes for each of the three signals. A dielectric rod extends from within the inner conductor and into the horn antenna for propagating the second signal out of and into the antenna.

Abstract: This invention provides a flat circular waveguide device which permits uniform radiation or power through a plurality of power-radiating openings in order to increase the antenna gain in the technical field of electric communications, especially, broadcasting antennas. To achieve such uniform radiation of power, the device is equipped with means for feeding power from a peripheral wall of a wave-guiding space, which is surrounded by metallic walls, toward a central part of the wave-guiding space.

Abstract: A broad band omnidirectional monocone antenna 10 having a wide operative frequency spectrum and a large elevation angle A is disclosed herein. The antenna 10 of the present invention includes an input circular waveguide network 12 and 18 for providing electromagnetic energy of at least one polarization. Coupled to the circular waveguide network 12 and 18 is a dielectric-loaded waveguide arrangement 22 for projecting a first electromagnetic beam. The inventive antenna 10 further includes a parasitic element network 32, 34, and 36 positioned in the path of the first beam. The parasitic element network 32, 34, and 36 is disposed to form a parasitic beam in response to the first beam. In a particular embodiment of the inventive antenna 10 a beam shaping cone 40 circumscribes the dielectric waveguide arrangement 22. The cone 40 is adapted to augment the elevation angle A characterizing the antenna 10 of the present invention by redirecting the parasitic beam.

Abstract: A wideband hybrid horn antenna in which a circular section horn (1) is fed by a circular feed guide (3). A dielectric polyrod (7) is cantilever mounted in the throat end (4) of the horn (1) and is tapered to provide a match to the guide (3). Its forward section is tapered from the guide diameter down to about 2 mm just outside the mouth (11) of the horn (1). The various dimensions--horn diameter at throat and aperture, flare angle, polyrod diameter taper and extent--are all chosen to produce a balance of opposing effects on the beamwidth and thus provide a fixed beamwidth substantially independent of frequency over a wide band. A large bandwidth, from 8 to 16 GHz in the particular case, is thus obtained with a substantially constant beamwidth over the band.

Abstract: A photoconductive antenna modulator which optically modulates a radio frequency carrier signal from a dielectric waveguide antenna is disclosed. A photoconductor film is placed in proximity with the dielectric waveguide antenna such that the radio frequency carrier signal from the antenna must be conducted through the film when it is radiated into space. The carrier is then optically modulated by variably illuminating the photoconductor film with light which has wavelengths near the photoconductor film's spectral region of photoconductor sensitivity, which decreases the photoconductor film's transparency to the radio frequency carrier signal. By varying the strength of the illumination on the photoconductor film, one is able to optically modulate the radio frequency carrier signal propagated through the photoconductor.

Abstract: An antenna includes a sheet of dielectric material having two parallel surfaces. A tapered recess in one surface converges towards the other surface with the axis of the recess orthogonal to said surface. The dielectric material has a critical angle of reflection with respect to the axis. A RF horn is located in proximity to the surface with the recess and has an axis in common with the axis of the tapered recess. A RF lens is located between the horn and the tapered recess. The optical properties of the RF horn, RF lens, tapered recess, and dielectric material are such that all rays traced from the horn through the lens and dielectric material to the second surface have an angle with respect to said normal of the second surface greater than said critical angle. RF energy on the second surface from the center of the horn is in phase with RF energy on said second surface from the edge of said horn allowing a surface wave to be launched on the second surface.

Abstract: Scanning tip for electromagnetic radiation having wavelengths below about 3 cm comprising a waveguide (10) which acts as high-frequency hollow waveguide and which comprises a wall (12) of an electrically conductive material and the internal cross-section of which diminishes from a point at which it has a magnitude which permits unrestricted propagation of the radiation perpendicularly to the cross-sectioin to an end aperture (14) having a dimension (s) which is small in comparison with the wavelength of the radiation, having a rod (20) which comprises an electrically conductive surface which is electrically insulated with respect to an electrically conductive inner wall of the hollow waveguide and extends from the aperture (14) at least up to said location (z=0).