Showing papers on "Slot antenna published in 1989"

The tapered slot antenna-a new integrated element for millimeter-wave applications

Abstract: Tapered slot antennas (TSAs) with a number of potential applications as single elements and focal plane arrays are discussed. TSAs are fabricated with photolithographic techniques and integrated in either hybrid or MMIC circuits with receiver or transmitter components. They offer considerably narrower beams than other integrated antenna elements and have high aperture efficiency and packing density as array elements. Both the circuit and radiation properties of TSAs are reviewed. Topics covered include: antenna beamwidth, directivity, and gain of single-element TSAs; their beam shape and the effect of different taper shapes; and the input impedance and the effects of using thick dielectrics. These characteristics are also given for TSA arrays as are the circuit properties of the array elements. Different array structures and their applications are also described. >

Compound radiating slots in a broad wall of a rectangular waveguide

Abstract: An analysis is presented of the characteristics of a broad wall radiating slot, offset from the center line and tilted with respect to the longitudinal axis of a rectangular waveguide. Pertinent integral equations are developed, taking into account finite wall thickness, and are solved for the slot aperture E-field using the method of moments. Compound slot characteristics are then deduced, including resonant length and dominant mode scattering. Numerical results for the scattering from resonant slots are presented over a range of offsets, tilt angles, frequencies and waveguide dimensions. For resonant compound slots, offset and tilt are shown to control the aperture electric-field amplitude with a phase variability of 360 degrees . The results have significant applications in the design of compound slot arrays. >

Horn array antenna

Abstract: PURPOSE: To prevent the reduction in gain and to suppress thermal noise generated in the inside of an antenna lower by arranging a horn antenna in an array, connecting a waveguide to the connection of horn antennas so as to combine power through the waveguide. CONSTITUTION: Horn antennas 1 are arranged as an array, waveguides 2, 3 are connected to the connection of each horn antenna 1 to combine the power with the waveguide. For example, 16 horn antennas 1 are arranged in an array of 4×4 to constitute the horn array antenna. The radiation efficiency of the horn antenna 1 is ≥80% being close to 90% and the waveguide 2 is directly connected to the horn 1 integrally to reduce the connection loss. Thus, the decrease in the gain is prevented and the thermal noise caused in the inside of the antenna is suppressed lower. COPYRIGHT: (C)1990,JPO&Japio

Analysis of a centered-inclined waveguide slot coupler

Abstract: Integral equations are developed for a centered-inclined coupling slot (including the effect of finite wall-thickness of the common broad-wall) and the slot-aperture electric intensity field is found using the method of moments. Numerical results for resonant length, backscattered wave amplitude, and phase variation off-resonance are presented over a range of values of the waveguide b dimension, wall thickness, slot width, and frequency. It is shown that the resonant length is relatively insensitive to slot tilt, theta , for a standard-height X-band waveguide, whereas its dependence on theta is significant for reduced-height waveguides. The phase variation of scattered TE/sub 10/ waves in both waveguides off-resonance is less for wider slots and smaller b dimensions. Shunt-series coupling slots exhibit greater phase variation off resonance when compared to a centred-inclined coupling slot. Also, the former has a longer resonant length for a smaller b dimension and for a wider slot. Thus the centred-inclined slot coupler possesses superior characteristics. The higher-order mode coupling between a centred-inclined slot coupler and a pair of straddling radiating slots in the branch waveguide is significant. >

Cavity-backed wide slot antenna

Abstract: We propose a wide slot antenna to expand the frequency bandwidth of a cavity-backed slot antenna. In the antenna the slot width is significant in comparison with the slot length. We present the analysis of the antenna including the feed line. The result obtained is a 35% frequency bandwidth (VSWR < = 2), which is also verified by experiment.

Slot antenna device for portable radiophone

Abstract: An antenna device of an easily carried portable radiophone, is provided, by disposing a slot antenna within an interior of the portable radiophone. The antenna device improves sensitivity of the device by arranging a slot antenna so as to transmit and receive vertical- and horizontal-polarized waves through the slot antenna device, which is constructed such that a conductive material is coated on a case of the portable radio telephone, an omni-directional first slot antenna for a vertical-polarized-wave is disposed horizontally over said case, and a second slot antenna for slant vertical-polarized or horizontal-polarized waves is disposed in a predetermined angle below said case, thereafter coupling in parallel a coaxial cable for feeding an electrical signal between each given position on the first and second slot antennas.

Frequency limitations on broad-band performance of shunt slot arrays

Abstract: Two methods are presented for the analysis of slot array performance as a function of frequency, taking mutual coupling into account. The first is a direct method, the other an iterative one. These are applied to a seven-slot resonant array and to a 21-slot traveling wave array. This analysis permits prediction of the bandwidth and provides comprehension of broadband limitations. The two examples presented show good agreement between theory and measurement. >

Axial slot antenna on dielectric-coated elliptic cylinder

Abstract: The radiation properties of an axial slot antenna on a conducting elliptic cylinder with a homogeneous dielectric coating are investigated. In the dielectric coating and in the exterior free-space region the field is expanded in elliptic waves using the Mathieu functions. The Mathieu angular functions are employed as basis and testing functions to enforce the boundary conditions at the interface between the dielectric and the free-space regions. The equations of continuity at the boundary are solved by Galerkin's method. Numerical results are presented in graphical form for the transverse electric (TE) and transverse magnetic (TM) polarizations to illustrate the far-field radiation patterns, the gain versus coating thickness, and the aperture conductance versus coating thickness. >

Distribution network for phased array antennas

Abstract: A distribution network for a modified space-fed phased array antenna consists of a planar array of radiating slots distributed along a coplanar wall in each of an ensemble of parallel waveguides. This waveguide ensemble is fed or excited by an orthogonal waveguide or waveguides, through a row of slots in a wall common to the excitation waveguides and the parallel waveguide ensemble, one slot per waveguide. A predetermined amplitude distribution is achieved in the plane parallel to the axis of the exciting waveguide by adjusting the coupling value of each exciting slot, and in the orthogonal plane by adjusting the displacement of the radiating slots from the center line of the waveguides, and by adjusting slot width, length, and geometry. Such an array of slots is used to feed the inside face of a quasi-space-fed antenna array having identical, individual electronics modules.

An accurate moment method model for the tapered slot antenna

Abstract: A moment-method model is presented for the radiation characteristics of the tapered slot antenna. It overcomes the shortcoming of an earlier theory. The method is rigorous for the air dielectric antennas. For dielectric-supported antennas, the method is approximate but accurate. The method is particularly accurate for antennas etched on substrates that are electrically thin or have a low dielectric constant, within the limits of ( epsilon /sub r/-1)d/ lambda /sub 0/ >

A slot coupling control in circularly-polarized radial line slot antennas

Abstract: The authors predict the gain performance for a CP-RLSA (circularly polarized radial line slot antenna) with reduced slot coupling and propose a basic design for slot coupling control (SCC). When the CP-RLSA can be used near the resonant frequency with weak coupling, the bandwidth becomes 1.5 times as wide as that of an antenna without SCC. SCC for this purpose is possible by the determination of the slot coupling angle. The proposed design was verified experimentally. >

A projection method providing low sidelobe pattern in conformal array antennas

Abstract: The authors present a novel method for the analytical determination of the amplitude distribution providing the low sidelobe pattern of conformal array antennas. The proposed projection method considers both the nonuniform element density and element patterns on the aperture. Numerical results are given as well as results of experimental verification for an X-band, half-spherical array with 60 rectangular microstrip antennas. >

Aperture field and circuit parameters of cavity-backed slot radiator

Abstract: The general problem of a cavity-backed aperture radiator is formulated for the tangential electric field in the aperture. The result is used to obtain an integro-differential equation for the special case of a narrow slot backed by a rectangular cavity resonator. This equation is then solved numerically by the method of moments with the proper choice of piecewise sinusoidal basis and testing functions to remove the differential operator in the integrand. Typical numerical results are presented to show the effect of various cavity and slot dimensions on quantities such as voltage distribution along the slot, input impedance, resonance frequency and bandwidth of the antenna.

Radial line slot antenna

Abstract: PURPOSE: To use a circularly polarized wave, a horizontally polarized wave and a vertically polarized wave in common by providing a 1st slot group formed in spiral, a 2nd slot group in parallel with the Y axis and a 3rd slot group in parallel with the X axis. CONSTITUTION: A circularly polarized wave slot 11 is arranged on a spiral 12 to obtain a circularly polarized wave, and a horizontally polarized wave slot 14 is formed on a space of the circularly polarized wave slot 11 as a slot group in parallel with the Y axis placed on plural semi-circular-arcs whose interval is λg to use the two polarized waves in common. Moreover, a vertically polarized wave slot 15 is formed on a space of the polarized wave in common slot group as a slot group in parallel with the X axis placed on plural semi- circular-arcs whose interval is λg to use the 3rd polarized wave in common. Thus, three kinds of slot patterns orthogonal to each other for the circularly polarized wave, the horizontally polarized wave and the vertically polarized wave are in existence and the mutual interference is minimized, then the aperture face of the antenna is used in common. COPYRIGHT: (C)1992,JPO&Japio

Investigation of planar antennas for submillimeter receivers

Abstract: A frequency-scaled model of a tapered slot antenna has been investigated. The antenna consists of a dielectric substrate which serves as a carrier for a tapered slotline. The width and the shape of the slotline and the dimensions of the substrate (including the value of the permittivity) have been varied to investigate the radiation patterns. The result is a planar antenna with a symmetrical beam in the E and H planes and a beam efficiency of almost 50%. The substrate thickness is the most important limiting factor for scaling the model to submillimeter frequencies. Taking away parts of the dielectric substrate in the front area of the antenna allows a relatively large substrate thickness. The variations of the half-power beam width versus slot parameters, versus the dielectric thickness of the substrate, and versus the length and the width of the substate are presented. In addition the beam efficiency has been measured for various frequencies, and the radiation pattern has been calculated for comparison. >

Equivalent antenna radius for narrow slot apertures having depth

Abstract: The problem of electromagnetic penetration of a narrow slot aperture in a thick perfectly conducting plane is reduced to the solution of Hallen's integral equation with an equivalent antenna radius. The depth and width of the slot are assumed to be small compared to both the length of the slot and the wavelength. The equivalent radius is evaluated in terms of the solution to the transverse static problem. Simple approximations for the equivalent radius is also given. Hallen's integral equation is solved by the Galerkin method with piecewise sinusoidal basis functions. Large slot depth-to-width ratios give rise to vanishingly small equivalent radii and thus large antenna resonance quality factors. A simple correction to the static field distribution in the slot is also given. This correction allows the depth to become somewhat larger relative to the wavelength. >

Vehicle slot antenna with parasitic slot

Abstract: A slot antenna is disclosed for a horizontal dielectric vehicle door in which the ground plane of the antenna sheet does not connect with or overlap the surrounding electrically conducting vehicle body panels but which nevertheless maintains significant RF currents at FM frequencies through the vertical roof pillars of the vehicle. This is accomplished by the formation of a parasitic slot surrounding the antenna slot in the gap between the sheet and the surrounding sheet metal at the trunk opening. The parasitic slot has a first portion of length substantially the same as that of the antenna slot and a similar width and a second portion of a greater width effective to comprise an open circuit for currents. Thus the total effective length of the parasitic slot is equal to that of the antenna slot for similar resulting current flow from the decklid area through the vertical roof pillars; and the desirable FM performance is preserved. If the second portion of the parasitic slot is placed on a vertical portion of the door, backward horizontal radiation is also improved; and interference due to operation of an electric latching mechanism for the door is reduced if it is mounted in the second portion of the parasitic antenna.

Radiation properties of slot and dipole elements on layered substrates

Abstract: This paper presents calculations of the radiation properties of slot and dipole antennas on electrically thick, grounded, dielectric substrates. These structures offer the possibility of simplifying the fabrication of imaging array antenna structures which operate at millimeter wave and far infrared freqeuncies. They also offer the possiblility of good beam patterns which can be tailored to suit a specific need. We present an analysis of practical layered structures which have beam patterns that are suitable for millimeter wave and far-infrared imaging array applications. We discuss considerations of the choice of dielectric layers with regard to beam patterns, surface wave losses, and the type of element used. The effects of dielectric and ground plane losses in high-gain structures are also considered. Efficiencies and beam patterns for three and five layer structures are presented, although the analysis techniques are extendable to an arbitrary number of layers. It is found that in combination with the use of a twin element configuration, both slot and dipole antennas can overcome the problems of losses to surface waves in the substrate. Consequently, they can be made to efficiently radiate to air on these layered dielectric structures.

Dual-loop slot antenna with simple feed

Abstract: A dual-loop slot antenna consisting of two identical loops fed by a triplate line is proposed. It is experimentally demonstrated that the antenna radiates a unidirectional beam of linear polarisation. It is also shown that the generation of a circularly polarised wave is possible by adding perturbation elements to the loops.

Theoretical design/synthesis of slotted waveguide arrays

Abstract: A computer aided design/synthesis procedure for array antennas of the slotted waveguide type is described. It differs from earlier contributions to this topic in that it uses theoretically evaluated self-admittances, rather than measured self-admittances, for the individual broadwall slots in the array. By adopting the moment method to generate the slot self-admittances, it is shown that accuracies which are comparable with those obtained from a measurement based procedure can be achieved.

Dual polarized ambidextrous multiple deformed aperture spiral antennas

Abstract: An antenna group comprising a plurality of spiral antennas occupies a circular space The spiral antennas are radially symmetrically arranged about a point at the center of the circle Each spiral antenna is deformed to occupy a substantially all of the area within a sector of the circle The antenna may be used for detection of circularly-polarized waves of either polarization sense, or may operate with phase-sensing means to locate the source of incoming electromagnetic radiation

A moment method analysis of linearly tapered slot antennas

Abstract: A moment method analysis is used to calculate the current distribution on a linearly tapered slot antenna. The surface current distribution is computed for several test cases. The results for an antenna with L/ lambda =5.2, W/ lambda =2.5, and 2 gamma =14 degrees are shown. Radiation pattern results are in good agreement with experimental data. >

A feasibility study of stripline-fed slots arranged as a planar array with circular grid and circular boundary

Abstract: An experimental study of the self-impedance of stripline-fed slots has been undertaken, with slot length and slot offset relative to the strip as parameters. The slot is cut in one wall of a parallel plate waveguide, and locally a cylindrical cavity is created around the slot by two rho =constant walls and two phi =constant walls. Such cavities can be used as modules to build a circular-grid planar array. Anticipating a corporate feed, it is demonstrated that sufficient dynamic range in the self-impedance to overcome the effects of mutual coupling is achievable, thereby opening up the prospect of an efficient circular-grid array for seeker antenna applications that require good sum and difference patterns. >

Dual polarised phased array antenna

Abstract: A dual polarised phased array antenna is formed by intersecting two parallel sets of circuit boards (11,12) respectively carrying orthogonally polarised antenna elements (17). In prior antennas corresponding orthogonal elements mutually coincided with board intersections and interengagement slots restricted on-board circuit interconnection of elements. In the improvement the elements (17) are spaced from the board intersection slots (14) facilitating circuit interconnection along the board. Also the phase centres (16) of those antenna elements (17) relating to one polarisation direction are offset from the phase centres of corresponding antenna elements relating to the other polarisation direction. An array employing Vivaldi slot antenna elements is described

Two numerical solutions for the parallel plate-fed slot antenna

Abstract: An integrodifferential equation for the electric field in the aperture of a parallel-plate waveguide-fed slot antenna is numerically solved using Galerkin's method, with a basis of edge-condition-weighted Chebyshev polynomials, and pulse expansion with point matching. Efficient algorithms are obtained for the elements of the reduced matrix equations for both moment methods. The numerical convergence of the techniques is demonstrated by the resultant aperture field distributions and input reflection coefficients for the case of dominant (transverse electromagnetic) mode excitation. >

Source localization using a distorted antenna

Abstract: A method is proposed for estimating both the outline of a distorted array antenna and the bearings of some incident plane waves. This is possible if locations are known for a number of sensors equal to the number of remote sources present. Using an operator named the propagator, which can be extracted adaptively from the data, the shape of the whole antenna can be restored, and thus the usual superresolutive direction-finding algorithms can be applied efficiently. Owing to the adaptive character of the method, the case of time-varying antenna shape and/or moving sources can also be handled. This method is particularly useful when the number of sensors is much greater than the number of sources, and it imposes only a low computational burden. >

Analysis of the 'microstrip-loaded inset dielectric waveguide'

Abstract: The authors describe the properties of a microstrip-loaded inset dielectric guide (MSLIDG) and its application to a strip-loaded antenna with horizontal polarization. Dispersion curves are presented for the microstrip-like mode for a MSLIDG with a=22.84 mm, h=10.16 mm, l=2 mm, and the theoretical values of lambda /sub g/ are compared with the values measured in the range of single-mode operation. Attention is also given to the design of a 22-element horizontal array operating at 10.2 GHz. >

Endfire tapered slot antenna characteristics

Abstract: Typical configurations and operating characteristics for endfire tapered slot antennas are described. The feed transition modeling and moment method modeling techniques are utilized to predict antenna performance. The radiation pattern and cross polarization properties for the linearly tapered slot antennas are examined. Endfire tapered slot antennas are applicable for wide-band scanning arrays and focal plane arrays for imaging and multiple beam reflector systems.