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Showing papers on "Slot antenna published in 1990"


Patent
17 May 1990
TL;DR: In this paper, an exponentially tapered slot (Vivaldi) antenna for producing an end-fire beam was proposed, which has a novel balun for coupling with a feed line.
Abstract: An exponentially tapered slot (Vivaldi) antenna for producing an end-fire beam. The antenna features a novel balun for coupling with a feed line. The conventional Vivaldi antenna is fed by means of a stripline section (1) underlying the ground plane (5) and lying perpendicular to the axis of the slot line (3). This balun arrangement has an inherent narrow bandwidth. In the proposed antenna arrangement the slot line (14) and the stripline (16) each have a 45° twist centered on a common cross-over point (X o ,Y o ). The stripline (16) is terminated by a short-circuit to the ground plane (12) and the slot line (14) is terminated by an open-circuit in the form of a circular slot (15). The E-plane and H-plane radiation characteristics are similar to those of the conventional Vivaldi antenna, but the arrangement has a broadband capability enabling operation over any 3 to 1 bandwidth in the frequency range 1 to 40 GHz.

167 citations


Proceedings ArticleDOI
07 May 1990
TL;DR: In this article, the slot design for aperture field synthesis in a single-layered RLSA (radial line slot antenna) is summarized, where the slot length and the spacing are varied on the basis of a full-wave analysis.
Abstract: The slot design for aperture field synthesis in a single-layered RLSA (radial line slot antenna) is summarized. In order to realize a desired slot coupling, the slot length and the spacing are varied on the basis of a full-wave analysis. An example is presented concerning the design of the uniform aperture field distribution. >

78 citations


Journal ArticleDOI
01 Oct 1990
TL;DR: In this article, a set of integral equations for the fields in the slot is derived, based on the field equivalence theorem, and is solved numerically by Galerkin's method.
Abstract: A radial line slot antenna (RLSA) is a nonresonant multimode waveguide slotted array. The slot coupling to the radial waveguide in this antenna is analysed. A parallel plate waveguide with a periodic boundary condition is used to simulate a sectral region of the circular aperture in a RLSA. A set of integral equations for the fields in the slot is derived, based on the field equivalence theorem, and is solved numerically by Galerkin's method. Theoretical results effectively express the measured effects of the various antenna design parameters on the slot coupling.

65 citations


Patent
25 Jan 1990
TL;DR: In this paper, a broadband microwave antenna exhibiting high radiation efficiency over a broad frequency band in which the VSWR is less than 2.5:1 over at least 15% of the frequency band, includes a ground plane at one side of a dielectric substrate and formed with at least one slot, and a feed strip at the other side of the substrate.
Abstract: A broadband microwave antenna exhibiting high radiation efficiency over a broad frequency band in which the VSWR is less than 2.5:1 over at least 15% of the frequency band, includes a ground plane at one side of a dielectric substrate and formed with at least one slot, and a feed strip at the other side of the substrate. The feed strip is of uniform width for substantially its complete length, but includes a change in width at the feed end of the slot to produce a first impedance matching network effective to bring the slot impedance to the level of the feed line over the broad frequency band, and another change in width at the load end of the slot to produce a second impedance matching network which reduces the slot reactance to match the reactive impedance of the load to the reactive part of the slot impedance over the broad frequency band.

37 citations


Journal ArticleDOI
TL;DR: In this paper, a resonant coupling slot cut in the common broad wall of two crossed rectangular waveguides is analyzed, where the slot is offset from the center line and tilted with respect to the longitudinal axis of the main waveguide, whereas it is centered-tiled in the branch waveguide.
Abstract: A resonant coupling slot cut in the common broad wall of two crossed rectangular waveguides is analyzed. The slot is offset from the center line and tilted with respect to the longitudinal axis of the main waveguide, whereas it is centered-tiled in the branch waveguide. It is shown that the slot offset and tilt control the branch waveguide excitation amplitude with a phase variability of 360 degrees . Pertinent integral equations are developed, taking into account finite wall thickness. The integral equations are solved for the slot aperture electric field using the method of moments. Dominant mode scattering by the slot in both waveguides is obtained. >

34 citations


Journal ArticleDOI
TL;DR: In this article, a model which allows prediction of element gain and aperture efficiency of the feed/reflector system is presented, and the predictions are in good agreement with experimental results, showing that TSA arrays used in multibeam systems with small beam spacings are competitive in terms of aperture efficiency with other more standard types of arrays incorporating waveguide type elements.
Abstract: A class of feed antennas and feed antenna arrays used in the focal plane of paraboloid reflectors and exhibiting higher than normal levels of cross-polarized radiation in the diagonal planes is addressed. A model which allows prediction of element gain and aperture efficiency of the feed/reflector system is presented. The predictions are in good agreement with experimental results. Tapered slot antenna (TSA) elements are used as an example of an element of this type. It is shown that TSA arrays used in multibeam systems with small beam spacings are competitive in terms of aperture efficiency with other, more standard types of arrays incorporating waveguide type elements. >

33 citations


Journal ArticleDOI
TL;DR: In this paper, the authors considered the problem of electromagnetic penetration of a narrow slot aperture in a thick conducting plane when the conductivity of the plane and slot walls is large but not necessarily infinite and when somewhat lossy gaskets are placed in the slot.
Abstract: The problem of electromagnetic penetration of a narrow slot aperture in a thick conducting plane is considered when the conductivity of the plane (and slot walls) is large but not necessarily infinite and when somewhat lossy gaskets are placed in the slot. The problem is partitioned into a local region, where transmission line theory is used to describe the antenna modes along the slot, and a nonlocal region, where a filament-type integral representation is used. The result is a modified Hallen-type integro-differential equation for the slot voltage (or magnetic current). The local transmission line theory allows the effects of wall loss and gaskets to be included in a simple and intuitive manner. Examples involving a rectangular slot aperture are given. The finite conductivity of the conducting plane, even for good conductors, reduces the penetration when realistic slot dimensions are used. Gaskets, even with relatively small loss tangents, also reduce the penetration when realistic slot dimensions are used. >

30 citations


G. Hygate1
24 Jan 1990
TL;DR: In this paper, a dipole scatterer similar to Hajnal's has been used monostatically for the first time to make measurements in the reactive near field of an antenna.
Abstract: Any attempt to measure a microwave field pattern inevitably results in some perturbation of that pattern. The conventional method, using a probe antenna connected via a length of waveguide to a remote receiver, perturbs the fields considerably because the probe antenna and the waveguide connected to it are electrically conducting and large compared with the wavelength of the radiation. Distortion of the original fields by the probe antenna is not troublesome if the probe antenna is far from radiating or reflecting objects, but it prevents accurate measurement of the fields close to source antennas or reflectors. Hajnal (1987) used a plastic optical fibre to bring the light from a modulated light-emitting diode to a photosensitive load at the centre of a short dipole scatterer; this was then used to make bistatic measurements in the far-fields of antennas at a single frequency. In the work described here, a scatterer similar to Hajnal's has been used monostatically for the first time to make measurements in the reactive near field of an antenna. The spot-frequency homodyne detector used by Hajnal has been replaced by a broadband instrument, constructed using coaxial components and designed to work over the frequency range 2-18 GHz.

29 citations


Proceedings ArticleDOI
07 May 1990
TL;DR: An accurate analysis and detailed characterization of a leaky-wave antenna based on a metal-strip-loaded dielectric inset waveguide and a detailed parametric analysis indicate that this class of antennas exhibits a significant degree of flexibility in terms of achievable electric characteristics.
Abstract: An accurate analysis and detailed characterization of a leaky-wave antenna based on a metal-strip-loaded dielectric inset waveguide are presented. A detailed parametric analysis is presented, illustrating how the various parameters can affect its characteristics. In addition, an example of how the insight gained through this analysis permits one to design structures with a prescribed behavior is given. The analysis performed and the results obtained indicate that this class of antennas exhibits a significant degree of flexibility in terms of achievable electric characteristics. This feature and its inherent mechanical simplicity make the structure analyzed a very promising candidate for millimeter-wave antenna applications. >

28 citations


Proceedings ArticleDOI
07 May 1990
TL;DR: In this article, a matching slot pair for a circularly polarized slotted waveguide array is designed to suppress reflection and realize a desired polarization in the tilted beam direction, which contributes to the improvement of the antenna efficiency.
Abstract: The analysis and the design of the matching slot pair for a circularly polarized slotted waveguide array are described. The position and the size of the slots are numerically optimized to suppress reflection and to realize a desired polarization in the tilted beam direction, which contributes to the improvement of the antenna efficiency. A boundary value problem is analyzed for the matching slot pair taking the wall thickness of a waveguide into account in order to evaluate the phase of aperture fields accurately. The position and the size of the slots are determined on the basis of this analysis. The design is verified by measuring the reflection coefficient, the radiation patterns, and the axial ratio of a model slot pair. It was verified experimentally that the return loss is below -15 dB over 0.1 GHz at the 4-GHz band and the 3-dB axial ratio bandwidth is about 5% in the titled beam direction. >

28 citations


Journal ArticleDOI
TL;DR: In this paper, the authors analyze a slot in a conducting plane separating different media when the slot is illuminated by a transverse electric and a transversal magnetic plane wave, and provide numerical results for the characteristic currents, the equivalent magnetic currents and the field pattern for a slot whose width is a function of the wavelength.
Abstract: The authors analyze a slot in a conducting plane separating different media when the slot is illuminated by a transverse electric and a transverse magnetic plane wave. The general characteristic mode theory for different media is used for the solution of this problem. The characteristic modes, which are computed using the method of moments, provide numerical results for the characteristic currents, the equivalent magnetic currents, and the field pattern for a slot whose width is a function of the wavelength. Analytical expressions for the narrow slot are also given. >

Patent
04 May 1990
TL;DR: An antenna with unidirectional sensitivity includes a slot-forming means defining a plurality of substantially concentric and generally coplanar annular slots and a non-resonant antenna connection for transmitting electromagnetic energy to and from the plurality of annular slot as mentioned in this paper.
Abstract: An inexpensive, efficient, broadband, slot-type antenna with unidirectional sensitivity includes a slot-forming means defining a plurality of substantially concentric and generally coplanar annular slots and a non-resonant antenna connection means for transmitting electromagnetic energy to and from the plurality of annular slots. The antenna connection means forms a plurality of non-resonant, radially-extending cavities that are adapted to combine electromagnetic energy received at the plurality of concentric, annular slots substantially in phase and to divide electromagnetic energy between the plurality of concentric, annular slots for transmission from the slots generally in phase and along the central slot axis that lies perpendicular to the two concentric, annular, coplanar slots. The antenna may also include a plurality of polarizing antenna elements carried by the slot-forming means adjacent at least one or two of the substantially concentric, annular slots to enhance the unidirectional sensitivity of the antenna. Such a plurality of polarizers may be carried by the slot-forming means in a plurality of locations spaced above and over at least one or two of the concentric annular slots and oriented and distributed around their peripheries at locations to correct for variations to polarity and to suppress cross-polarization to and from the antenna.

Journal ArticleDOI
TL;DR: In this article, a planar, monolithic twin slot antenna integrated with a bismuth microbolometer detector for operation near 94 GHz is presented, and measured receiver gain beam patterns are compared with theoretical patterns for a number of cases.
Abstract: We have constructed a planar, monolithic twin slot antenna integrated with a bismuth microbolometer detector for operation near 94 GHz. In this paper, we briefly discuss the theory of operation for planar antennas on a dielectric stack. We then cover the fabrication details, including a short discussion of a photoresist bridge technique used to fabricate the microbolometer detectors. Measured receiver gain beam patterns are then compared with theoretical patterns for a number of cases.

Proceedings ArticleDOI
01 Oct 1990
TL;DR: In this paper, two types of tapered slotline antennas (TSA) have been studied for submillimeter wave-lengths, where the substrate is difficult to thin down.
Abstract: Two types of tapered slotline antennas (TSA) have been studied. One type, which requires a fairly thin substrate, gives a radiation pattern of high gaussicity. For submillimeter wave-lengths, where the substrate is difficult to thin down, a sandwich type with thick substrate and superstrate has been studied. The radiation patterns for the sandwiched antenna are substantially improved when an elliptical lens is added.

Journal ArticleDOI
TL;DR: A notable increase in the average received power has been observed in operation in an urban area where the field distributes randomly and consists of cross-polarized components.
Abstract: The receiving performance of mobile antenna systems that have vertical and horizontal elements at the 920-MHz band has been investigated by measurements in both rural and urban areas in Japan. Three types of inverted-F antennas for a car and three types of antenna elements, a monopole, a bent-slot and an inverted-F antenna, for portable equipment were used in the experiments. The average received power and its probability density function are obtained as the parameter to evaluate the performance of antenna systems. The performances of the bent-slot antenna system for portable equipment and the inverted-F antenna system mounted on a car are compared with those of the monopole or dipole antenna systems used as reference antennas. A notable increase in the average received power has been observed in operation in an urban area where the field distributes randomly and consists of cross-polarized components. >

Proceedings ArticleDOI
07 May 1990
TL;DR: A numerical analysis of correlation coefficient characteristics with antenna separation and incoming wave distribution for a built-in diversity antenna system comprising two planar inverted-F antennas mounted on both sides of the radio case found that even small antenna separation yields a sufficiently low correlation coefficient.
Abstract: The authors present a numerical analysis of correlation coefficient characteristics with antenna separation and incoming wave distribution for a built-in diversity antenna system comprising two planar inverted-F antennas (PIFAs) mounted on both sides of the radio case. It was found that even small antenna separation yields a sufficiently low correlation coefficient. Mutual couplings between the two antennas were found to play a major role in obtaining low correlation coefficients. It was also found that the built-in diversity antennas have good performance in terms of effective gain. The calculated results were in fairly good agreement with experimental results. >

Patent
01 Nov 1990
TL;DR: In this paper, the ear-like dipole elements are rotated with respect to the slot in order to fine tune the polarization direction, and the earlike elements are disposed in a symmetrically opposed relationship along the elongated edges of the slot.
Abstract: An antenna (10) incorporating a slot (12) and a plurality of ear-like dipole elements (13a,b). The antenna comprises a ground plane (11) having a slot (12) disposed therein, and a plurality of ear-like elements (13a,b) attached to one side of the ground plane along the elongated edges of the slot (12). The ear-like elements (13a,b) are oriented orthogonal to the ground plane (11) in the same direction. Typically, the plurality of ear-like elements are disposed in a symmetrically opposed relationship along the elongated edges of the slot. The plurality of ear-like elements typically comprise two generally quadrant-shaped elements having the centers of the respective quadrant-shaped elements are disposed at or near the outer edges of the slot and the outer edge of the elements extend to about the middle of the slot. The ear-like elements may be rotated with respect to the slot in order to fine tune the polarization direction. In a typical antenna, a plurality of slots are employed, and the present invention permits the use of randomly oriented or regularly spaced slots that are fed by means of conventional rectangular waveguides or boxed stripline. An polarized radiation field having a controlled arbitrary polarization is selectively produced by controlling the relative positions of the slot and ear-like elements. Typically, if all the energy radiates from the ear-like elements, then tile antenna is polarized along the slot. If all the energy radiates from the slot, then the antenna is polarized across the slot. When both the slot and ear-like elements radiate energy, then the antenna is linearly polarized if both the slot and ear-like elements radiate in phase, circularly polarized if both the slot and ear-like elements radiate with equal amplitude and the phase difference between them is ±90 degrees, and elliptically polarized if the excitation amplitude and phase associated with the slot and ear-like elements are not the same.

Patent
06 Dec 1990
TL;DR: In this paper, the antenna combination of the invention is particularly suitable for transmitting and receiving in vehicles because antennas which have transmitting and reception properties equivalent or superior to those of rod and disc antennas can be built into the vehicle.
Abstract: The antenna combination has at least two individual antennas which form part of at least one resonant circuit which appears on an electrically conductive surface. The output signals of the individual antennas are combined, for example, added. The antennas are preferably located at the edges of the electrically conductive structure. The antenna combination of the invention is particularly suitable for transmitting and receiving in vehicles because antennas which have transmitting and receiving properties equivalent or superior to those of rod and disc antennas can be built into the vehicle. The antenna combination can be used advantageously in a diversity process.

Patent
16 May 1990
TL;DR: In this paper, a symmetrical 180° microwave hybrid is constructed by opening a slot line in a ground plane below a conducting strip disposed on a dielectric substrate, creating a slot coupled conductor.
Abstract: A symmetrical 180° microwave hybrid is constructed by opening a slot line in a ground plane below a conducting strip disposed on a dielectric substrate, creating a slot coupled conductor. Difference signals propagating on the slot coupled conductor are isolated on the slot line leaving sum signals to propagate on the microstrip. The difference signal is coupled from the slot line onto a second microstrip line for transmission to a desired location. The microstrip branches in a symmetrical fashion to provide the input/output ports of the 180° hybrid. The symmetry of the device provides for balance and isolation between sum and difference signals, and provides an advantageous balance between the power handling capabilities and the bandwidth of the device.

Proceedings ArticleDOI
L. Josefsson1
07 May 1990
TL;DR: In this paper, the moment method using global sinusoidal expansion and testing functions has been used for the analysis of scattering from a single slot in a screen as well as a slot backed by a waveguide.
Abstract: The moment method using global sinusoidal expansion and testing functions has been used for the analysis of scattering from a single slot in a screen as well as a slot backed by a waveguide. The method is basically the same as that used for slot admittance calculations. The results agree with the radar cross section in the (Babinet) equivalent strip dipole case. Slot fields have been computed for several cases including oblique incidence. Finite wall thickness is also treated. Bistatic scattering from a slot loaded with a waveguide section on the rear side was studied. The coupling to the waveguide modes in the waveguide was also obtained. Oblique incidence is shown to produce an asymmetrical field distribution which results in nonsymmetric coupling to the waveguide modes as well as a nonsymmetric bistatic cross section distribution. >

Patent
23 Feb 1990
TL;DR: In this article, a planar microwave antenna having a resonant back structure constituting a common back plane cavity for an array (20,27) of resonant slots (21). The back structure comprises a sheet of metal having an arrangement of mechanically pressed projections forming lands (23).
Abstract: A planar microwave antenna having a resonant back structure (22) constituting a common back plane cavity for an array (20,27) of resonant slots (21). The back structure (22) comprises a sheet of metal having an arrangement of mechanically pressed projections forming lands (23). The projections extend towards the regions between the slots (21) of the array (20) and are so shaped and positioned that the lands (23) do not intrude into areas of the back plane exposed by the slots (21). The lands (23) provide a rigid support for the slot array (20) and reduce the dimensional tolerance problems encountered in antennas having a single flat back plate. Further, the projections reduce the number of possible degenerate waveguide modes to give an improved antenna performance. The provision of a common back cavity also enables a closer slot spacing than can be achieved when using individual cavities for each pair of slots. The back structure can be manufactured at low cost without recourse to specialist pressing techniques or the use of expensive alloys. A slot antenna incorporating the back structure is suitable for use in DBS (Direct Broadcast by Satellite) TV reception.



Patent
21 Feb 1990
TL;DR: In this article, a planar microwave antenna having a resonant back structure constituting a common back plane cavity for an array (20, 27) of resonant slots (21). The back structure (22) comprises a sheet of metal having an arrangement of mechanically pressed projections forming lands (23).
Abstract: A planar microwave antenna having a resonant back structure (22) constituting a common back plane cavity for an array (20, 27) of resonant slots (21). The back structure (22) comprises a sheet of metal having an arrangement of mechanically pressed projections forming lands (23). The projections extend towards the regions between the slots (21) of the array (20) and are so shaped and positioned that the lands (23) do not intrude into areas of the back plane exposed by the slots (21). The lands (23) provide a rigid support for the slot array (20) and reduce the dimensional tolerance problems encountered in antennas having a single flat back plate. Further, the projections reduce the number of possible degenerate waveguide modes to give an improved antenna performance. The provision of a common back cavity also enables a closer slot spacing than can be achieved when using individual cavities for each pair of slots. The back structure can be manufactured at low cost without recourse to specialist pressing techniques or the use of expensive alloys. A slot antenna incorporating the back structure is suitable for use in DBS (Direct Broadcast by Satellite) TV reception.

Journal ArticleDOI
TL;DR: In this article, a method is described for calculating the input impedance as seen by the detector for a twin-slot antenna structure, which is then used to analyze several twin slot antenna configurations, leading to improved performance.
Abstract: A method is described for calculating the input impedance as seen by the detector for a twin slot antenna structure. This technique is then used to analyze several twin slot antenna configurations, leading to improved performance.

Patent
14 Sep 1990
TL;DR: In this paper, a known circular slot antenna is improved such that its horizontal and vertical polar diagram has a comparatively high antenna gain and such that the vertical polar diagrams has as far as possible no antenna gain at all underneath the antenna.
Abstract: 2.1 A known circular slot antenna is intended to be improved such that its horizontal and vertical polar diagram has a comparatively high antenna gain and such that the vertical polar diagram has as far as possible no antenna gain at all underneath the antenna. 2.2 On the underside (12) of the conductive wall (10), the vehicle antenna according to the invention has a cavity, which coaxially surrounds the circular slot (11), in the form of a pot (13). 2.3 A preferred field of application for the vehicle antenna is a motor vehicle antenna for the 900 MHz band. 3. The drawing shows a perspective sectional view of the vehicle antenna.

Patent
11 Dec 1990
TL;DR: In this article, an array antenna which includes a first waveguide 12 coupled to a second waveguide 20 by an L-shaped coupling slot 30 is presented. But the proposed design is not suitable for planar antennas.
Abstract: An array antenna which includes a first waveguide 12 coupled to a second waveguide 20 by an L-shaped coupling slot 30. The slot 30 has a first portion 32 orthogonal to a second portion 34 thereof thereby providing the unique L-shape. In a specific embodiment, the slot 30 is located with the first portion 32 along the centerline and longitudinal axis of the first waveguide 12 and the second portion 34 along the centerline and longitudinal axis of the second waveguide 20. The folded short, as well as the tapered section of prior designs can be eliminated by use of the L-shaped coupling slot of the present invention in the first and last positions of the coupling slot because a short can be placed at the L-shaped slot. Hence, the L-shaped coupling slot of the present invention provides a more compact planar antenna than that afforded by conventional designs.

Proceedings ArticleDOI
07 May 1990
TL;DR: In this paper, a K-band four-element linear phased array of printed dipole antennas has been designed and tested, and a coplanar waveguide (CPW) is used for the microwave distribution system.
Abstract: A K-band four-element linear phased array of printed dipole antennas has been designed and tested. This array radiates in the end fire direction and is suitable for large two-dimensional arrays. A coplanar waveguide (CPW) is used for the microwave distribution system. A CPW to twin strip transition is used to interface with the printed dipole antennas. MMIC (microwave monolithic integrated circuit) phased shifters are used for phase control. This array demonstrates the advantages of CPW for MMIC integration and microwave signal distribution. The radiation characteristics of the antenna are excellent. >

Patent
25 Oct 1990
TL;DR: In this paper, a printed circuit plate (PCP) is placed in a narrow wall of the waveguide and a microstrip line is connected to the plate to excite the slots with the energy thus tapped.
Abstract: In a waveguide (1) having slots (2, 3) perpendicular to the axis of the waveguide and cut in a narrow wall of the waveguide, a printed circuit plate (4) is positioned. This plate has patches (5, 7) for coupling with the energy being propagated in the waveguide and microstrip lines (6, 8) connected to the patches to excite the slots (2, 3) with the energy thus tapped. These slot waveguides can be used particularly in array antennas.