Abstract: A base station clustered adaptive antenna array includes a plurality of clusters of antenna elements. Each cluster is spaced away from an adjacent cluster by a first predetermined spacing related to receive-mode beamforming and includes a plurality of transmit-receive antenna elements. Each element within the cluster is spaced away from an adjacent element by a second predetermined spacing related to transmit-mode beamforming. In order to reduce the visual impact of the antenna array, each cluster is included within a single exterior housing or radome. A medial receive-only antenna element may be provided between adjacent clusters to enhance beamforming for reverse link reception.

Abstract: The invention relates to a method for coupling a signal to an antenna structure, as well as to an antenna structure, which comprises at least two antenna elements (101, 102), a ground plane (105) for grounding the antenna structure, a coupling line (106) for coupling a first antenna element and a second antenna element to each other, and a feeding line (107) for feeding the antenna structure through one feeding point. The first antenna element (101) is next to the ground plane and perpendicular to the ground plane (105). The second antenna element (102) is above the ground plane and parallel to the ground plane. The first antenna element is arranged to receive information on a reception band of a broadband radio system and the second antenna element is arranged to transmit information on a transmission band of said broadband radio system.

Abstract: A broadband partial fan cone direction finding antenna and array disclosed. The antenna includes a radiator having a partial cone shape. The radiator substantially occupies a spatial area defined by a portion of a cone and the cone is defined by a cone axis, a cone height, and a cone angle. The cone has a base and an apex, and the portion of the cone is defined by a cone sweep angle. The cone sweep angle is determined as the angle subtended by a projection of the portion of the cone projected onto a plane that is perpendicular to the cone axis. The cone sweep angle is less than 360° so that the portion of the cone is bounded on its sides by edges which extend radially from the apex of the cone outward to the base of the cone.

Abstract: A system and method are disclosed for deploying a plurality of point-to-point receiver transmitter pairs such that the main beam of transmitting radio does not point directly at any receiving radio antenna other than the desired receiving antenna. A three dimensional lattice matrix deploying nodes in different horizontal planes and aligning the nodes such that nodes of a particular row of nodes do not point directly at one another is used. Accordingly, particular horizontal and vertical angles, ideally greater than ½ the main beamwidth, are used to align nodes of the lattice. Additionally, inter-nodal distances and polarization isolation are taught to improve mutual interference.

Abstract: An array antenna apparatus for use in spread spectrum communications is provided including a plurality of antenna elements aligned on a straight line. The array antenna apparatus is used in a receiving station for receiving spread-spectrum modulated radio signals having a wavelength of a predetermined carrier frequency transmitted from transmitting stations using a two-dimensional RAKE receiving method, and for performing spread spectrum communications in code division multiple access. The plurality of antenna elements are aligned such that an interval between antenna elements adjacent to each other among the plurality of antenna elements is set to a value which is larger than one half the wavelength of the carrier frequency and which is equal to or smaller than sixteen times the wavelength of the carrier frequency so as to generate grating lobes.

Abstract: The present invention relates to a multi-band cellular basestation and in particular relates to antennas for such basestations. There is a growing need for mult-band basestation antennas for mobile communication systems, to serve existing 2nd generation systems, and emerging third generation systems. For example, GSM and DCS1800 systems currently coexist in Europe, and emerging 3rd generation systems (UMTS) will initially have to operate in parallel with these systems. The present invention provides a dual/triple/multi-band performance cellular basestation antenna having a shared aperature, having a first set of radiating elements operable at a first frequency range; a second set of radiating elements operable at a second frequency range; wherein the first set and second set of radiating elements are arranged in an interleaved fashion.

Abstract: The invention relates to active repeaters for transmission systems used in mobile telephony. The active repeater comprises an antenna constituted by a plurality of juxtaposed radiating elements which are grouped together in two separate identical matrix arrays, amplification paths for connecting each radiating element of one array to the radiating element of the other array having the same matrix position, with each amplification path having identical gain and phase shift so that the wave received by the first array at an angle of incidence &thgr; is retranmsitted by the second array as a wave having an angle of incidence &bgr; such that &thgr;=&bgr;. The invention is applicable to mobile telephone systems.

Abstract: The present invention relates to a wireless local loop (WLL) system using a patch-type antenna which is provided with microstrips and can be installed indoors. In a WLL system wherein there are provided a base station for relaying transmitted/received signals and a terminal for exchanging these signals between the base station and a telephone or a modem. The present invention includes a patch-type antenna that is detachable/connectable from/to the terminal.

Abstract: The present invention relates to an antenna array adapted to radiate or receive electromagnetic waves of one or two polarizations with very low cross polarization and low sidelobes. An antenna array comprising many antenna elements, e.g., more than ten antenna elements, is provided in which formation of grating lobes are inhibited in selected directions of the radiation and cross polarization within the main lobe is suppressed at least 30 dB below the main lobe peak value. According to a preferred embodiment of the invention, the antenna elements of the antenna array comprise probe-fed patches, preferably rectangular patches, more preferred, square patches. Further, it is preferred that the feed probes are positioned at the axis of symmetry of the square or rectangular patches.

Abstract: The elements of a spatially aperiodic phased array antenna have an unequally spaced circular distribution, that is effective to decorrelate angular and linear separations among elements of the array. For any radial direction passing through an element of the array, the vector distance from any point along that radial direction to any two elements of the array is unequal and uniformly distributed in phase, modulo 2.pi.. Angular separation between successively adjacent antenna elements varies in accordance with an Nth root of two, wherein N is the number of antenna elements in the array. To locate each element, a first element is placed at any arbitrary location along the circumference of the array. The angular spacing .alpha..sub.1 of a second element relative to the first element is defined such that .alpha..sub.1 =2.pi.*(2.sup.1/N -1). The angular spacing .alpha..sub.j of each additional element relative to the first element is defined by .alpha..sub.j =.alpha..sub.j-1 *2.sup.1/N, where j varies from 2 to N.

Abstract: An antenna arrangement for a fixed wireless access base station comprising at least one pair of directional antenna wherein the pair of antennas have a common phase centre. If both antenna in the pair then operate on the same frequency channels, the correlation of fading of same sector co-channel interference can be maximised. To provide full cell coverage a plurality of pairs of antenna are arranged spaced apart in a tier about a support and to provide spatial diversity a second tier of antenna substantially the same as the first and which is vertically separated from the first tier is added.

Abstract: A surface wave directional detection system for determining the direction in which an electromagnetic wave propagating along a metallic surface is travelling includes a first loop probe and a second loop probe positioned in close proximity to the metallic surface so that the electromagnetic wave induces a signal in each of the loop probes. The two loop probes are separated by a quarter wavelength so that the two signals induced in the probes are out of phase. The first and second loop probes are connected by equal length transmission lines to a quadrature hybrid which generates two output signals that vary in magnitude in correspondence with the direction of travel of the electromagnetic surface wave. The two output signals from the quadrature hybrid are provided to RF detectors, which generate output voltage signals that vary in proportion to the magnitude of the output signals from the quadrature hybrid.

Abstract: A cylindrical, omnidirectional antenna array includes a plurality of vertically spaced circular rows and a plurality of angularly spaced vertical columns, with an antenna element located at each row-column intersection. The antenna elements included in one 180.degree. sector of the cylindrical array are vertically polarized, while the antenna elements included in the other, diametrically opposed 180.degree. sector are horizontally polarized to provide polarization diversity. Optionally, the antenna may be adapted as a sector antenna array by reducing the number of columns and the angles of the diametrically opposed sectors to less than 180.degree..

Abstract: A phased array antenna is designed for scanning a narrow beam over an angular sector that is wide in one plane, and narrow in another, while using a minimum number of phase steering controls. High directivity elements occupy a rectangularly shaped area which is large in one direction relative to a second direction, the elements being staggered in position with neighboring elements to suppress near-in grating lobes. The elements are independent and identical to one another so that conventional array beamforming techniques may be utilized.

Abstract: A micro-diverse directional antenna array positioned proximately upon the boundary of a convex shape whereby the primary attenuation lobes of neighboring antennae overlap. This creates a situation in which the reception of signals by said array from the space-time-delay domain of transmission can be effectively modeled as a banded linear transformation upon discretized space-time-delay domain of transmission yielding the antenna reception at discrete time steps.

Abstract: A base station arrangement for a cellular radio system comprising an antenna array, is disclosed. The downlink signals transmitted from antennas have a spacing which is scaled in proportion to the transmitted and received wavelengths. A method of operation is also disclosed.

Abstract: A system and method for determining the minimum number of radiating elements required to achieve desired operating characteristics for a circular array of radiating elements. In one embodiment, the present invention determines the number of radiating elements required to space the radiating elements about the periphery of a circle such that a circular array of radiating elements is generated. The radiating elements are spaced apart from each other by a distance which is related to the wavelength of radiation at which the radiating elements operate. The present invention evaluates the maximum and minimum electric field strength generated by the circular array of radiating elements. By comparing the maximum field strength to the minimum field strength, the present invention measures the maximum ripple generated by the circular array of radiating elements. The maximum ripple generated by the circular array of radiating elements is then compared with a predetermined acceptable ripple level.

Abstract: A planar antenna comprises an emitting circuit plate having an emitting element made of a micro-strip antenna element, a first dielectric plate, and a feeder circuit plate having a feeder line, in which said feeder line are electromagnetically connected to said emitting element in said emitting circuit plate, and said emitting element is a ring circular emitting element containing a cross bridge conductor in the center thereof.

Abstract: A tilted helical element antenna array has increased effective aperture. By tilting individual helical radiators relative to one another, the region of aperture overlap may be decreased to thereby increase the effective aperture of the array. Helical radiators are disposed at a radiator spacing which is less than the operating wavelength .lambda.. At such a small spacing, the apertures of each of the helical radiators overlap. To decrease this aperture overlap region and thereby increase the effective aperture of the array, each of the helical radiators are tilted relative to one another. Thus, a compact antenna having an increased effective aperture is provided.

Abstract: A direction finding antenna system includes a plurality of monopole elements disposed symmetrically around a center of a circular ground plane at the same radial distance from the center and a multimode combiner connected to the monopole elements to provide one or more mode outputs. A phase difference detector determines phase differences between selected ones of the mode outputs to provide azimuth bearing of a detected object. Typically, four or eight monopole elements are used. Placement of the inherently narrowband monopole elements in a bicone structure having a polarizer grid extends the useful bandwidth. Multiband coverage is achieved with a plurality of such antennas connected by a feed cable positioned on the polarizer grid to avoid interference.

Abstract: An energy transmission arrangement is formed as a subarray panel which emits a microwave energy signal to a target location on the basis of a pilot signal received from the target location. The subarray panel includes a transmission antenna divided into a subarray having a plurality of antenna elements for transmission of the energy signal. The subarray panel further includes pilot signal receiving antennas and thus each subarray panel may function independently and may thus be made lighter and more compact.

Abstract: An antenna having an omnidirectional pattern in azimuth and coverage throughout a hemisphere. The radiating elements are four half-loops mounted on a ground plane. Each half-loop is approximately one-half wavelength in length with one end grounded to the ground plane and the other end fed in opposition to the ground plane. The image produced by the ground plane of each half-loop, together with the actual half-loops give the effect of a set of four complete loops, each of which complete loops is approximately one wavelength in circumference. The elements are nominally located in planes normal to the ground plane that pass through a central point in the ground plane. The planes of the elements are oriented nominally at 90 degree intervals about a central point and the centers of the elements are offset from the central point of the ground plane by approximately one-quarter wavelength. The combination of elements produces an omnidirection radiation pattern in azimuth.

Abstract: A phased array antenna (PAA) that is particularly adapted to accommodate communications with low earth orbiting (LEO) satellites includes three antenna faces which comprise a phased array of radiating elements, each antenna face is triangular and the three faces form a triangular pyramid. Each triangular face has a height h and a base length B. B and h are chosen to optimize the antenna's gain variation with beam elevation angle to compensate for the path losses dependent on beam elevation angle. At low elevation, increased free space loss in incurred due to longer range to a low earth orbiting satellite, and more rain and atmospheric loss is incurred due to longer path through the atmosphere compared with the losses at higher elevations or at zenith. Since the intrinsic shape compensates for the elevation dependent losses, the PAA design minimizes total array area compared with other known geometries and thus exhibits lower cost.

Abstract: A distributed antenna system is utilized in a system for providing multipath signals which facilitate signal diversity for enhanced system performance. Each node of the antenna comprises more than one antenna. Each antenna at a common node provides a path having a different delay to the base station.

Abstract: An amplitude monopulse direction finding system is disclosed. The system is built around a circular array with a circular lens in which the antenna elements and array ports are larger than in conventional systems. The oversized antenna elements and array ports provide a wide range of operating frequencies for the direction finding system. Additionally, the direction finding system contains an omni-directional probe at the center of the lens to detect the presence of signals. In an alternative embodiment, each array port is split into two halves which can be combined in different ways to produce different beam patterns, allowing the beam pattern providing the best signal to noise ratio to be selected. Also, built-in-test circuitry is described.

Abstract: An antenna is composed of a number of subarray radiating elements, with an aperiodic geometry, which assures connections between satellites and between satellites and ground stations. The aperiodic structure makes it possible to eliminate possible interference acting on the connection. The possible presence of the array grating lobes during steering of the array beams in the angular sector of interest is reduced. The presence of a grating lobe within the field of view which can cause interference with another low orbiting satellite is avoided, so as to improve reception quality characteristics. The invention is applicable to microwave antennas and space-borne systems by eliminating the presence of grating lobes in the field of view.

Abstract: Arrays of helical antennas are desired for operation at spaced-apart frequencies, such as 1.5 and 2.5 GHz. In order to reduce mutual coupling between the antenna elements of the lower-frequency array, they are spaced apart by more than .lambda.. Grating lobes occur due to the spacing. The lengths of the lower-frequency helices are adjusted to move the nulls in their radiation patterns into congruence with the unwanted peaks of the array pattern, thereby suppressing the grating lobes. In order to reduce the total area of the combined arrays, the higher-frequency antennas of the second array are interleaved with the elements of the first array. At the higher frequency, the antenna elements of the second array are spaced apart even further, in terms of wavelength, than the elements of the first array, so mutual coupling of the antennas of the second array is reduced even more than in the first array.

Abstract: An antenna system particularly suited for wind profiling produces a radio beam which can be oriented in each of four directions and optionally in a fifth, vertical direction and four intermediate directions. The antenna has a single array of strings of coaxial-colinear antenna elements. The strings are formed into sections, with each section having a first string portion formed of cable elements which are longer than one-half wavelength of the radio frequency drive signal in the cable and a second string portion formed of cable elements which are shorter than one-half the wavelength of the drive signal, with the two strings being connected together and mounted parallel to and above and below one another. Power is directed to the strings so that the radio frequency power flows in opposite directions in each string portion. The beam radiated from each string portion in each section adds to produce a beams tilted from the normal to the string portions by the same angle for both string portions.

Abstract: A distributed antenna system comprises a plurality N of spaced apart antennas 3, each antenna being connected to a RF line 2 via a circulator 4, wherein each circulator 4 is arranged to pass to its associated antenna a fraction 1/N of the RF power incident thereon.This can allow cost savings in providing the components needed for the antenna installation.

Abstract: In a point to point microwave communication service including a microwave antenna system at each point directed at the other point, the radiation pattern of the antenna system at at least one point has a substantial null in the direction of an antenna of another microwave communication service to avoid an exchange of signals with the other service, the antenna system provided at said one point includes two antenna elements having substantially equal directional radiation patterns, so oriented and spaced apart a distance that is at least several wave length of the operating frequency of the elements so that the radiation patterns of the elements overlap producing a net radiation pattern that results from interference of the patterns and the net pattern has a substantial lobe in the direction of the other point of said service and a substantial null in the direction of an antenna of the other microwave communication service.

Abstract: A radio transmission antenna system and method of transmitting radio signals.The antenna system includes an array of separately rotatable directional antennas which are spaced along an azimuth line. The antennas are rotated to direct their respective major lopes of transmitted rf energy along parallel lines in a selected direction relative to the azimuth line. Two separate adjustments are made to the phase of identical rf signals which are fed to each antenna in the array.A first phase adjustment is made when required to produce a coherent wave-front transmitted in the selected direction. This first phase adjustment shifts the phase of the signals fed to adjacent antennas in the array by 180.degree.. This adjustment establishes a radiation pattern in any given azimuth quadrant which records major lobes, established by rotating the antennas, at 0.degree. and 90.degree. relative to the azimuth line and at least one intermediate angle between 0.degree. and 90.degree..

Abstract: Antenna device for detecting a direction of an object lying in a low angle direction, which is constructed with a plurality of antenna elements, feeds, and so forth, and comprises a central feed for feeding RF signals to one or a plurality of central antenna elements, and a peripheral feed for feeding RF signals to a plurality of peripheral antenna elements, and that one of input terminals of the central feed and one of input terminals of the peripheral feed are connected together by a hybrid circuit.

Abstract: A phased array antenna (10) includes a plurality of radiating elements (14) arranged in concentric rings (11, 12) to form a deterministically thinned antenna aperture which facilitates heat removal from the array, while minimizing side lobe signals and thereby increasing directively of the antenna for a preselected antenna gain. The radiating elements (14) in any one of the rings (11, 12) are the same radiating size, and the spacing (L, L') between elements in the same ring and between elements in adjacent rings (S, S') is determined by the number of elements in each ring. The rings may be any of several shapes, including circular or polygonal.

Abstract: An antenna array for receiving microwave signals is provided that is particularly designed for use in television receive only (TVRO) satellite earth stations. The array comprises a plurality of identically-directed microwave antenna elements arranged in a plane perpendicular to their common primary receiving direction. Each antenna element includes an integral low-noise amplifier (LNA). Outputs of the LNAs are combined to produce a composite output signal which provides maximum response to microwave radiation arriving from the common primary receiving direction of the elements and null responses to microwave radiation arriving from particular other directions. The array includes means for rotating the elements about an axis parallel to the common primary receiving direction. Such rotation effectively adjusts the angle between the primary receiving direction of the array and a null-response direction disposed in a plane perpendicular to the plane of the array.

Abstract: An interferometer spiral antennae array having a deformable cavity-less spacer which can be shaped to a nonplanar surface without distorting the alignment of the spiral antennae or increasing the difficulty of aligning Alignment is increased by mounting the spiral antennae the antennae. The accuracy of antennae on a stratum, separate from a ground plane by the deformable spacer. The spiral antennae are electrically connected to RF components on a stripline or microstrip feed/balun circuit board by integral finger-like extensions of the circuit, extending through the ground plane and the deformable spacer, thereby eliminating the need for connectors or cables.

Abstract: A method for obtaining a linear cellular array employing cosine-squared antenna patterns is disclosed. The array herein described provides an essentially infinite linear band of coverage utilizing only six frequencies. The embodiment of this invention provides early frequency reuse and superior co-channel interference to existing cellular systems used today. An alternate embodiment provides total area coverage along selected portions or the entire linear band of cellular coverage.

Abstract: The field component diversity antenna and receiver arrangement comprises at least a first pair of parallel spaced, straight, vertical elemental antenna elements disposed substantially parallel to the electric field component of a transmitted signal to receive the transmitted signal in a multipath fading environment where the electric field and magnetic field components are uncorrelated and a 180.degree. hybrid circuit coupled to the first pair of spaced antenna elements to provide a first output signal proportional to the electric field components and a second output signal proportional to the magnetic field component. The spaced elemental antenna elements may be monopole elements or dipole elements. The pair of antenna element may be connected together by a straight conductor to enhance the magnetic field component. The first and second output signals may be combined by known diversity combining arrangement to achieve a diversity advantage.

Abstract: A coded linear array antenna comprised of a plurality of multiple element barrays, each providing sin mx/sin x patterns which are combined, i.e. summed into a composite pattern by having the subarrays commonly connected to a signal summation means. Each subarray is comprised of multiple elements which are respectively spaced equidistantly apart and positioned symmetrically on either side of a common array axis center or axis of symmetry and wherein the individual antenna elements of each subarray are positioned at an i.sub.th location according to the normalized equation ##EQU1## where i=1, 2, 3, . . . h, n.sub.m defines the maximum number of elements in the length or aperture of the composite array, h is the number of elements in the respective subarray, and n is proportional to the element spacing of the respective subarray.

Abstract: An array antenna comprised of n individual elements where n is an integer wer of the base two. The individual elements have predetermined space code positions N which are varied by means of a plurality of tracking loops comprised of a portion of receiver apparatus coupled to the array and a null seeking detector which is adapted to vary the space code positions of the elements such that the elements are selectively spaced at respective N' locations relative to the N locations to provide a predetermined 180.degree. phase difference between sets of elements operating in pairs at each space angle of arrival of each of M interference signals whereby a null and substantially complete cancellation of the interfering sources are simultaneously provided while retaining the ability to receive the desired signal at its peak received value.

Abstract: A method is disclosed whereby adjacent transmitting antenna arrays may be more closely spaced to each other and to receiving antenna arrays while still maintaining a high level of isolation between arrays. In each antenna array, first and second parts thereof are identified. The two parts of each transmitting array are driven in phase quadrature with each other and at substantially equal power levels, and the antenna arrays are spaced sufficiently close to each other so that radiation emitted by one array and received by another array undergoes a cancelling effect before reaching the RF generator associated with the other array. The two parts of each receiver array are coupled to their associated receiver by a signal path such that substantially quadrature phasing is established between the first and second parts thereof to cause received radiation to cancel in the signal path before reaching the receiver.

Abstract: Disclosed herein is a radar jammer which utilizes an electronically agile, sparsely populated, phase controlled antenna array of pseudo-randomly spaced radiating elements to form a high gain, single narrow beam of radiation directed at a detected threat radar, but containing only a small fraction of the available transmitting power, while providing simultaneously therewith effective jamming radiation over a wide coverage region. Preferably, the plurality of radiating elements are sparsely disposed pseudo-randomly over an area surface to form an antenna array, the number of radiating elements in the array being less than the value of the surface area divided by the transmitting carrier wavelength (.lambda.) squared.

Abstract: In an antenna array for radiating Instrument Landing System localizer signals, a method for reducing the required number of antenna elements by the combination of average element to element spacing exceeding one wavelength and end-fire directive antenna elements which suppress spurious radiation that would otherwise occur.

Abstract: A microwave oven having a directional rotating antenna axially supported on an axis of one wall of a microwave oven cavity of the microwave oven which provides circularly symmetric uniform energy distribution of microwave energy within the microwave oven cavity and consistent heating of a product in the microwave oven cavity. The directional rotating antenna includes a two-by-two array of antenna elements where each element is an end driven half-wavelength resonating antenna element supported by a length of conductor perpendicular to the wall of the microwave oven cavity. A parallel plate transmission line connects to each of the supports, four of which join at a junction which connects to a cylindrical probe antenna. The probe antenna is excited by microwave frequency currents of a waveguide adjacent to the wall of the microwave oven cavity. The directional antenna is rotated by a moving stream of air circulated through the microwave oven cavity.

Abstract: To isolate adjacent elements of an antenna array from each other, each feeder contains a power divider with four terminals, two of which are connected to the power dividers associated with the adjacent elements. The power dividers feed r.f. energy to the inactive elements in such a way that the latter no longer act as parasitic elements. The r.f. power dividers are so designed that three is a mismatch when looking from the antenna toward the power divider. This gives a further improvement in the isolation between adjacent antennas.

Abstract: The two channel transmit only antenna includes a balanced antenna and a ground plane disposed between the two radiators of the balanced antenna. The two radiators are fed by a three wire arrangement having one conductor connected to ground and the ground plane and two conductors each connected to a different one of the two radiators. A first channel filter is coupled between a first source providing a first transmit signal in a first frequency channel and one of the two conductors and a second filter is coupled between a second source providing a second transmit signal in a second frequency channel and the other of the two conductors. At least one resistor is connected between the two radiators.

Abstract: A method for optimally siting cosine-squared antennas in an array is taught, along with the array which is produced by use of the array. The array in question utilizes a dense hexagonal cellular grid, and each individual antenna is assigned a frequency group on which the antenna operates. The cells are ordered in such a fashion as to keep co-channel interference to a minimum.

Abstract: An electronically scanned antenna system having a linear array of endfire elements. The endfire elements are laterally spaced between about 0.3 .lambda. to 0.9 .lambda. apart, preferably about 0.55 .lambda. apart, to enhance the effects of mutual coupling therebetween for broadening the radiation signal pattern of the elements in the plane of the array. Advantageously, the endfire elements may be of the Yagi type with each endfire element including a common reflector, a driver, and a plurality of directors.

Abstract: An array antenna for radiating wave energy signals into a selected region of space and suppressing radiation in other regions of space is formed with an aperture which is an array of N antenna element modules, each comprising two or more antenna element groups, and each group comprising one or more antenna elements. A plurality of 2N first transmission lines is provided, each for supplying wave energy signals to one of the element groups. The antenna also includes N second transmission lines. Each of the second transmission lines has an input terminal, intersects a selected number of first transmission lines, and is terminated at its other end. Directional couplers are provided for coupling the second transmission lines to the intersected first transmission lines.

Abstract: An antenna array suitable for mounting at a selected height above a target plane, which provides for excellent resolution along a line in said plane extending through the vertical projection of the center of said array and perpendicular to a plane including said array. The array may comprise a plurality of radiators, each having a phase center along a support. The support is constrained to describe a segment of a circle in a vertical plane whose center lies on said line. As a result, the distance from any arbitrary point on the line in the target plane to any element of the array is equal.

Abstract: An antenna array comprising at least three interferometer pairs of antenna elements with selected spacings made to form a single beam which is readily scannable. All spatial frequencies generated by a signal and intercepted by the array are derived from a signal processing technique applied to the array. The array samples space in the spatial frequency domain while the signal processing technique utilizes real time convolution of functions in the spectral frequency domain. Summation of the appropriate spatial frequencies is equivalent to a Fourier transform operation, yielding the location of the signal source in space. Resolution and freedom from interference of the interferometer system is equal to that of a fully filled array of the same aperture size containing element spacings of one-half wavelength.