Abstract: A first dipole antenna consisting of dipole antennae 2a, 2b and a second dipole antenna consisting of dipole antennae 2c, 2d are disposed so as to be approximately orthogonal at approximately &lgr;/4 intervals on a reflecting plate 6 having a diameter of approximately &lgr;/2 or more. By disposing a plurality of non-feeding elements 3a to 3h around the first dipole antenna and second dipole antenna and isolating them by approximately &lgr;/4, the transmission gain and axial ratio in a low elevation angle can be improved.

Abstract: A phased array antenna includes an active or beam forming array portion, and active parasitic elements that transmit and/or receive signals. The parasitic elements serve the dual purpose of providing a uniform impedance for elements at the edge of the array portion of the antenna while also providing active elements that are used to transmit and/or receive signals. The active parasitic elements may transmit and/or receive at the same frequency as the array portion or at a different frequency than the array portion. It is also possible for the active parasitic elements to have a different polarization than the elements of the array portion.

Abstract: To reduce sidelobes in the radiation pattern of a phased array dipole antenna, a plurality of parasitic antenna elements are provided adjacent to the array of dipole elements of the antenna. The driven elements of the dipole array and associated director elements are formed as patterned conductor elements on one surface of a thin dielectric substrate. Feed elements for the driven dipole array also comprise patterned conductor elements formed on an opposite surface of the substrate. The feed elements have a geometry and mutually overlapping projection relationship with the conductors of the driven dipole elements, so as to form a matched impedance transmission line through the dielectric substrate with the patterned dipole elements. The parasitic elements are formed on additional dielectric substrates spaced apart from and parallel to the thin dielectric substrate upon which the driven dipole array is formed.

Abstract: An array antenna apparatus includes a radiating element (6) for transmitting and receiving radio signals, and at least one parasitic element (7) arranged at a predetermined distance (d) away from the radiating element (6) and incapable of transmitting or receiving radio signals. The parasitic element (7) is connected with a variable-reactance element (23). A controller (100) changes the directivity of the array antenna by changing the reactance Xn of the variable-reactance element (23). The variable-reactance element (23) is a varactor diode (D, D1), for example, and the controller (100) changes the backward bias voltage Vb applied to the variable-reactance diode (D, D1) to change the capacitance of the varactor diode (D, D1), thus changing the directivity of the array antenna. The array antenna has a low-cost and simplified structure compared with the prior art, while facilitating directivity control.

Abstract: Antenna elements A1 to A24 of a ring-shaped array antenna are selectively connected to power combiners each with a switch SH1, SH2 and SH3 one after another. When a direct wave and a reflected wave arrive in the directions of the antenna elements A5 and A3, respectively, the antenna elements A2, A5 and A8 in the power combiner SH2 are selected and their received signals are input into a receiver Rr to obtain therefrom an output Sr(2+5+6, f), and the respective antenna elements of the power combiners SH1 and SH3 are sequentially selected and their received signals are input into a receiver Rm to obtain therefrom outputs Sm(1, f), Sm(3, f), . . . . The outputs from the receivers Rr and Rm are caused to interfere with each other in an interferer 11 to detect an interference output to obtain data E(K, L).

Abstract: To reduce sidelobes in the radiation pattern of a phased array dipole antenna, a plurality of parasitic antenna elements are provided adjacent to the array of dipole elements of the antenna. The driven elements of the dipole array and associated director elements are formed as patterned conductor elements on one surface of a thin dielectric substrate. Feed elements for the driven dipole array also comprise patterned conductor elements formed on an opposite surface of the substrate. The feed elements have a geometry and mutually overlapping projection relationship with the conductors of the driven dipole elements, so as to form a matched impedance transmission line through the dielectric substrate with the patterned dipole elements. The parasitic elements are formed on additional dielectric substrates spaced apart from and parallel to the thin dielectric substrate upon which the driven dipole array is formed.

Abstract: An antenna arrangement is provide with a variable parasitic element whose position is varied as a function of the scan angle. According to an exemplary embodiment of the invention, a variable scanning array dual polarized antenna provides different scan angles by varying phase elements of the array. According to this embodiment an adjustable phase shift mechanism is used to modify the phase of the antenna array. The adjustable phase shift mechanism is used changes the antenna's phase as a function of a moveable dielectric slab. The dielectric slab slides over a microstrip line that results in a phase change that is a function of line coverage. A parasitic element is also connected to the dielectric slab such that the position of the parasitic element is varied in response to a change in the phase shift mechanism thereby varying the canceling signal of the parasitic element to optimize port isolation for the dual polarized antenna.

Abstract: A linear antenna capable of adjusting directivity and impedance matching comprises: a common dipole in which two cylindrical conductors each having a length of &lgr;/4 of the transmission frequency are provided linearly (thus having a total length of &lgr;/2); a plurality of linear parasitic elements that are provided at positions separated by a distance D2 from the axis of the common dipole so as to surround the common dipole; and a U-shaped parasitic element for realizing impedance matching that is arranged in proximity to one end of the common dipole. Each of the linear parasitic elements are arranged parallel to the common dipole and have a length of one half-wavelength of a desired transmission frequency.

Abstract: A radiating element for dual polarised operation in a linear antenna array is disclosed. The radiating element is a dual polarised radiating patch element consisting of a ground plane, a lower patch, an upper patch and parasitic elements. The lower patch and upper patch are stacked above the ground plane in a spaced apart relationship. The parasitic elements lie in the same plane as the lateral edges of the lower patch. Supports are used to hold the patches and the parasitic elements in a spaced apart relationship. The parasitic elements are fed from a central area of the lower patch by microstrips. The ground plane has apertures which are of a dumbbell shape to achieve the same effective length as long apertures. Orthogonally disposed strip type driven elements span across the central portions of the apertures and the length of these strips is selected to achieve the desired matchings.

Abstract: To reduce sidelobes in the radiation pattern of a phased array dipole antenna, a plurality of parasitic antenna elements are provided adjacent to the array of dipole elements of the antenna. The driven elements of the dipole array and associated director elements are formed as patterned conductor elements on one surface of a thin dielectric substrate. Feed elements for the driven dipole array also comprise patterned conductor elements formed on an opposite surface of the substrate. The feed elements have a geometry and mutually overlapping projection relationship with the conductors of the driven dipole elements, so as to form a matched impedance transmission line through the dielectric substrate with the patterned dipole elements. The parasitic elements are formed on additional dielectric substrates spaced apart from and parallel to the thin dielectric substrate upon which the driven dipole array is formed.

Abstract: A dual-polarized antenna system is provided for transmitting or receiving electromagnetic waves. The antenna system has at least one cruciform radiating element module that is aligned using dipoles or in the form of a patch radiating element, at angles of +45° and −45° with respect to vertical. The antenna system further has a conductive reflector arranged in the back of the at least one radiating element module. Two conductive side wall sections are provided on each side of the at least one radiating element and are disposed vertically. At least one slot is provided in each side wall section at the level of the radiating element module and extend in parallel to the reflector plane.

Abstract: A narrow and light mobile radio antenna that requires convenient supporting metal fittings provided in a base station is provided. An inner conductor of a coaxial feed line extends upward by a length of ¼ wavelength from the upper end of an outer conductor. This extended inner conductor forms an antenna element. Outside the coaxial feed line, a ¼-wavelength sleeve-like metal pipe made of brass is located with one end connected to the upper end of the outer conductor. On a part of the inner surface of the open end of the metal pipe, an internal thread is formed by tapping. In the open end of the metal pipe, an insulating spacer having an external thread formed around its periphery is inserted. In other words, the insulating spacer is located between the inner wall of the metal pipe and the outer conductor of the coaxial feed line. At the lower end of the coaxial feed line, a coaxial connector for connection with an external circuit is provided.

Abstract: To reduce sidelobes in the radiation pattern of a phased array dipole antenna, a plurality of parasitic antenna elements are provided adjacent to the array of dipole elements of the antenna. The driven elements of the dipole array and associated director elements are formed as patterned conductor elements on one surface of a thin dielectric substrate. Feed elements for the driven dipole array also comprise patterned conductor elements formed on an opposite surface of the substrate. The feed elements have a geometry and mutually overlapping projection relationship with the conductors of the driven dipole elements, so as to form a matched impedance transmission line through the dielectric substrate with the patterned dipole elements. The parasitic elements are formed on additional dielectric substrates spaced apart from and parallel to the thin dielectric substrate upon which the driven dipole array is formed.

Abstract: A low profile bi-directional antenna is provided for mounting directly to a metal structure, or some other conductive or semi-conductive surface. The antenna includes an insulating antenna tray, a conductive ground plane mounted to a surface of the antenna tray, first and second radiating elements extending from the ground plane, and a radome covering the radiating elements and fastened to the insulating antenna tray. First and second reflector elements are mounted to the surface of the antenna tray on the lateral sides of the ground plane. The reflectors are electrically connected to the ground plane. The radiating elements are supported above and to the lateral sides of the ground plane and reflector elements by support members mounted at acute angles to the ground plane. An RF connector is provided for coupling RF signals to and from the first and second radiating elements.

Abstract: A dual polarization antenna for transmitting/receiving polarized radio frequency signals includes a reflector plate that reflects the polarized radio frequency signals and one or more dipole assemblies. Each dipole assembly has two cross bow tie dipoles having radiating arms for transmitting/receiving the polarized radio frequency energy signals at two polarizations, and having U-shaped air-filled transmission feedlines for supporting respective radiating arms and providing the radio frequency signals between the reflector plate and the respective radiating arms. Each U-shaped air-filled transmission feedline includes two legs and respective feed rods arranged in respective legs. Each leg has a rectangular shape with three sides for isolating undesirable radio frequency energy. The radiating arms are triangularly-shaped and have notches dimensioned for minimizing radiation pattern distortion due to undesirable radio frequency coupling between the two cross bow tie dipoles.

Abstract: A directional antenna for telecomunication base station applications for home or business is provided. A folded dipole, a passive reflector, a balun and selectively routed coaxial transmission line all enclosed in a plastic enclosure provide improved stability of operating parameters when subjected to significant installation variations. The use of a PVC or similar plastic enclosure results in increased bandwidth while permitting printed circuit techniques and similar electronic construction methods the necessary protection and structural integrity.

Abstract: A no-loss, multi-band, adaptable Yagi style antenna employs a multi-element driven cell having a center element and one or more adjacent elements on each side of the center element. The adjacent elements of the driven cell are electrically shorter than the center element, thereby permitting the driven cell to be tuned to two or more frequency bands. The antenna is fed by a feedline connected to a common feed point at the center of the center element in the driven cell. Parasitic director elements are positioned in front of the driven cell and are tuned to the highest band of the driven cell. Parasitic reflector elements for one or more frequency bands are positioned behind the driven cell, with these elements tuned to actual operating frequencies of the antenna.

Abstract: Although conventional antennas have characteristics suitable for mobile radio base stations, their vertical dimension is large, and locations of their installation are limited. A radiator for an first upper antenna 32 is arranged in a hollow nonconductive radome 2, using an internal conductor 7a and a metal pipe 10. A radiator for a second lower antenna 34 is arranged in the radome 2, using metal pipes 14 and 15. Two parasitic elements 31 are installed substantially in parallel with the first antenna 32 below a feeding point 9. Two parasitic elements 33 are installed substantially in parallel with the second antenna 34 above a feeding point 13. These allow the tilt angle to be freely set between -10.degree. and +10.degree. by adjusting the parasitic element length and the antenna to be reduced in size.

Abstract: An antenna for receiving electromagnetic signals comprises: a ground plane with a length and having a vertical axis along the length. A plurality of dipole radiating elements, the radiating elements are comprised of first and second co-located, orthogonal dipoles, the dipoles are aligned at first and second predetermined angles with respect to the vertical axis, the radiating elements and ground plane produce first electromagnetic fields in response to said electromagnetic signals. A plurality of supports, the supports are connected to the ground plane and perpendicular to the vertical axis and placed between selected of the plurality of dipole radiating elements. A plurality of metallic parasitic elements are placed in a selected of said plurality of supports, the first electromagnetic fields exciting currents in said metallic parasitic elements, the currents creating second electromagnetic fields, the second electromagnetic fields canceling with portions of the first electromagnetic fields.

Abstract: A multiple beam antenna array utilizing strategically placed parasitic elements to control side lobe levels is disclosed. Two specific arrangements of such parasitic elements are taught. A first preferred arrangement of parasitic elements provides for their placement between a ground plane and a plane of active antenna elements. An alternative preferred arrangement of parasitic elements provides for their placement both between a ground plane and a plane of active antenna elements, as well as in front of the active antenna elements. Both such embodiments provide improved side lobe control over a similar antenna system without parasitic elements. Moreover, the characteristics of the main lobe are improved by both embodiments.

Abstract: A dual polarized aperture coupled patch antenna system having a back plate, a ground plane and a patch plane. The patch plane has a conductive patch layer forming a plurality of conductive patches on one side. The ground plane has a slot layer on one side and a microstrip feed network layer on the opposite side. The ground plate is positioned between the patch plane and the back plate, with the slot layer confronting the conductive patch layer of the patch plane and the microstrip feed network layer confronting the back plate. The slot layer comprises a conducting coating having a plurality of intersecting polarization slot pairs etched into the coating. The microstrip feed network layer comprises two feed lines and a plurality of feed probes. Two feed probe members are coupled to each conductive patch through one arm of each slot pair and one feed probe member is coupled to each conductive patch through each other slot pair.

Abstract: An improved dipole antenna array with high radiation directivity and broad bandwidth is disclosed. Each dipole antenna is driven by a balun structure composed of an unbalanced J-shaped transmission line placed over a pair of ground plane extensions that are separated by a channel. The dipole antenna arms are connected to an intermediate point on the ground plane extensions so that the balun structure extends beyond the dipole antenna. The length of the dipole arms, their position on the ground plane extensions, and the extent to which the balun extends beyond the dipole antenna can be chosen to determine the desired operating frequency range. The antennas are fabricated on ground and circuit planes separated by a dielectric material and composed of conducting material deposited on dielectric sheets. A planar array of dipole antennas is formed with the ground plane circumscribing each antenna in the array to improve directivity.

Abstract: An array antenna (12atf) particularly useful for a spacecraft includes a plurality of antenna elements (310). Each of the elements includes a conductive hexagonal cup (408) having sides (410a, 410b, 410c, . . .) which are thirteen twentieths of a wavelength long at the center frequency, and have a height above the bottom (412) which is a little more than one-third wavelength. A crossed dipole (420) includes two dipoles (420V, 420H), the first (421, 422) having elements approximately one quarter wavelength long, and the second (420H) having elements (423, 424) about three twentieths of a wavelength long. The plane of the crossed dipole is about one quarter wavelength above the bottom of the cup. A first director ring (512) has a diameter of about one quarter wavelength, and is spaced about nine tenths of a wavelength above the bottom. A second director ring (514) has a like diameter, and is spaced about seven tenths of a wavelength above the bottom of the cup.

Abstract: A dipole array antenna is configured for improved cellular operation by avoidance of metallic contacts which can lead to generation of intermodulation products (IMP). Isolated rectangular dipole radiators 12-17 are electromagnetically excited by perpendicularly aligned non-contacting exciter resonators 40-45. The rectangular exciter resonators 40-45 are integrally formed with microstrip signal distribution feed 18 supported above a ground plane 22. A non-contact RF grounded termination for the outer conductor of coaxial input line 52 uses a quarter-wave microstrip line section 56 to provide a low impedance RF path to ground to avoid IMP. An RF-isolated DC grounding circuit for surge protection includes a parallel combination of quarter-wave line sections 62 and 66. Line section 66 provides an RF open circuit path to a DC grounding post 67. Line section 62 provides a parallel non-contact low impedance RF path to ground, avoiding IMP from flow of an RF current through pressure contact points at post 67.

Abstract: A antenna system of the present invention comprises a radiator for radiating a radio frequency, which is converted from electric power, and which has a impedance matching unit and a power divider; a first reflector for reflecting and filtering the radio frequency; and at least one second reflector for filtering the radio frequency radiated in the sideward direction of the antenna system, which is vertically attached to the first reflector, and is able to be moved in a horizontal direction.

Abstract: Microwave devices incorporate at least one photosensitive baffle that is selectively illuminated, changing the baffle's electronic characteristic from being transparent to microwave energy to being reflective thereof. That action selectively alters an electronic characteristic of the microwave device. The effect is shown applied in a number of devices, including a back lobe antenna. Undesired back lobes occuring at a principal frequency are reduced in a back plane antenna by alternately coupling and decoupling an extension to the antenna's back plane at a rate sufficiently high enough to shift the back lobes to adjacent frequencies. A photoelectrically controlled baffle suitably serves as the extension.

Abstract: A horizontally polarized antenna array having extended E-plane beam width, and a method for accomplishing beam width extension. In one embodiment of the invention, an antenna array is provided that comprises a driven dipole element mounted to a conductive means forming a ground plane, the driven dipole element having opposing arms, and a pair of collinear parasitic dipole elements disposed on opposite sides of the driven dipole element, the parasitic dipole elements having opposing arms inclined toward the ground plane such that the opposing arms of each parasitic dipole element are perpendicular to one another.

Abstract: A driven element is disposed on an antenna axis for transmission of electromagnetic energy in a transmission direction along the antenna axis. First and second parasitic arrays are disposed on opposite sides of the antenna axis in the transmission direction from the driven element. At least a portion of the antenna axis adjacent to the parasitic arrays is without parasitic elements. Each parasitic array has a plurality of parallel parasitic elements or directors spaced apart along a respective array line that includes a proximal portion adjacent to the driven element that extends in a general direction that is at an acute angle to the transmission direction. The first and second parasitic arrays are sufficiently close to the antenna axis to produce a radiation pattern that has a lobe with greatest magnitude in the transmission direction.

Abstract: Multi-beam antennas with relatively large effective apertures for high antenna gain are provided for tower or pole mounting for cellular and other uses. Low wind resistance is achieved by use of thin cylindrical radiating units and thin cylindrical tuned reflector units. Each radiating unit includes separately excited upper and lower radiators, each including a microstrip pattern of a phase reversed series of half-wave transmission line sections on a substrate enclosed in a fiberglass tube radome. Each tuned reflector unit includes a resonant stack of electrically isolated metal rods enclosed in a fiberglass radome. In one embodiment, four cylindrical radiating units, each including upper and lower radiators, are laterally spaced in front of upper and lower reflector configurations, each including seven laterally spaced tuned reflector units.

Abstract: A non-imaging antenna system for the Instrument Landing System (ILS) utilizes a spatial filter network to provide a glideslope beam at a positive angle, while providing a null effect at a corresponding negative angle to reduce energy reflection at the glideslope angle. Four radiating elements, each including dipoles and a corner reflector, can be used as two overlapping vertical arrays of three elements each. A magic-T input junction is used to provide sum and difference glideslope beam signals to the overlapping arrays. The radiated signals of the two overlapping arrays provide aircraft guidance signals enabling an approaching aircraft to derive indications of high or low departures from the desired glide path. The array apertures may also be tilted from vertical to avoid coning effects of prior ILS antennas. Guidance signals compatible with the current ILS are provided, while avoiding site limitations, snow cover and other operating deficiencies of prior ILS antennas.

Abstract: The invention uses a modified Yagi-Uda antenna as a directional antenna for remote entry applications for transportation vehicles. To reduce the area that the antenna requires for packaging in a vehicle headliner, the antenna employs a shared reflector for plural reception zones on opposite sides of the vehicle. Since the antenna is packaged close to body sheet metal, a folded dipole is used as the antenna feed element to increase input impedance and simplify impedance matching with the receiver.

Abstract: A television broadcast invention comprising an elongated vertical support, a plurality of transmission lines extending upwardly along the vertical support, a plurality of primary radiators spaced along the length of the vertical support and connected to the transmission lines for radiating vertically polarized signals, and a plurality of parasitic radiating elements disposed radially outwardly from the primary radiators for re-radiating the vertically polarized signals as elliptically polarized signals. The primary radiators are preferably open-sleeve dipoles mounted on and surrounding a central hollow mast and fed by transmission lines extending along the hollow interior of the mast.

Abstract: Disclosed is an array antenna (10) that may be reconfigured to point in multiple directions. The array antenna includes a driven element (12) coupled to a transmission line (14) and a pair of passive elements (22) and (24). The passive elements (22) and (24) each include three antenna segments that are coupled together by a pair of optoelectronic switches (26) and (28), respectively. When the optoelectronic switches coupled to a particular passive element are closed the element functions as a reflector; when the switches are open, the element functions as a director. Other reconfigurable antennas are also disclosed, including antennas with reconfigurable gain and field pattern characteristics.

Abstract: The present invention relates to an antenna apparatus emitting or receiving high frequency waves and comprising four parasitic vertical rod elements disposed symmetrically to a central vertical rod element and switching elements controlled by a control circuit so that the parasitic rod elements are applied successively and periodically to the ground potential by the control circuit.

Abstract: An antenna comprises a base plate forming a ground plane, a coaxial feed serving as a mast connected to the base plate and extending along an axis that is normal to the ground plane, and two orthogonal dipoles each formed of two elements. Each dipole element has a first end connected to and supported by the mast at a first location spaced apart from the ground plane by a predetermined distance and a second end closer to the ground plane and exhibits a curvature in a plane containing the mast.

Abstract: The antenna has a support with a metallic structure and cables. In order to give the antenna good resistance to wind, it is made by means of rigid half-wave dipoles and these dipoles are mounted directly on the mechanical structure.

Abstract: An antenna comprising a linear array of active elements positioned in one or more rows. The back portion of the array is partially enveloped by a reflector. The reflector includes a backwall and at least one sidewall perpendicular to the backwall and extending forward of the backwall. In one embodiment of the invention, a single row of dipole radiators form the linear array. In a second embodiment of the invention, a row of folded monopoles mounted on an imaging ground plane form the linear array. The radiation pattern is directed forward of the reflector, the back radiation in the E-plane being suppressed by the sidewall of the reflector.

Abstract: The described embodiments of the present invention provide a high-gain antenna while allowing for the inclusion of devices within the antenna array. In one embodiment of the invention an array of receiver/transmitter elements is positioned in a pan-like reflector base. The elements are positioned one-quarter of a wavelength from the surface of the base. The wavelength is the wavelength of the chosen frequency of transmission or reception of the antenna. A partially reflective plate is positioned one-half wavelength from the base and thus one quarter wavelength from the elements. Reflective disks are also positioned one-half wavelength above the base and are positioned directly above the elements. The disks create a resonant cavity around the elements for waves of the chosen frequency arriving from near normal to the plane of the base or being emanated from the elements at a normal or near-normal angle. The partially reflective plate extends this resonant area spatially from the element.

Abstract: A dipole antenna system includes a driven dipole element and two parallel parasitic dipole elements equally spaced from the driven dipole element. Dual polarization can also be achieved by using two such systems arranged orthogonally.

Abstract: A simplified short backfire directional antenna provides both sum and error adiation patterns in the H-plane. Three parallel dipoles are mounted above a pan-type reflector, with a small metal reflector disc over the dipoles. The center dipole is excited to produce a sum pattern and the two end dipoles are excited out of phase to provide an error pattern with a broadside null in the H-plane. Alternatively, a hybrid circuit may be used with a pair of parallel dipoles to generate the desired patterns. Improved gain and resolution are achieved with a small antenna array.

Abstract: An antenna system is provided having a common reflector and a plurality of spaced apart end-fired yagi type elements each comprising a driver and one or more directors. The elements are positioned longitudinally parallel to each other in separate planes. Adjustable parasitic reflecting rods are located adjacent to the elements so as to cause the generation of a low energy scattering field which, in turn, increases inter-element isolation.

Abstract: An L-band radar and antenna array operating with an existing X-band surveance radar to provide a foliage penetration capability. The foliage penetration antenna consists of an array of L-band, stripline dipole/director elements placed in front of an array of broadwall waveguide slots which define an X-band aperture. The X-band aperture in addition to its own function, serves as a reflector for the dipole/director elements. Aperture sharing is thus provided for a dual frequency antenna without increasing the size of the existing X-band aperture.

Abstract: Antenna having a selectively rotatably extendable sensitivity pattern provided by an array of three or more dipole antenna units, each of substantially equal mechanical length and located at the corners of a substantially regular polygon having the same number of sides as the number of units in the array and switching means having connections to each dipole unit to selectively energize at least one of said units and interpose an electrically-lengthening inductive reactance in at least two other units located, with respect to the direction in which the sensitivity is to be extended, behind and on either side of an energized unit to serve as parasitic reflectors extending the lobe of sensitivity of an energized unit in the selected direction.