Showing papers on "Slot antenna published in 1993"

Double-slot antennas on extended hemispherical and elliptical silicon dielectric lenses

Abstract: Far-field patterns and Gaussian-beam coupling efficiencies are investigated for a double-slot antenna placed on hemispherical lenses with varying extension lengths. The radiation patterns of a double-slot antenna on a silicon dielectric lens are computed using ray-tracing inside the dielectric lens and electric and magnetic field integration on the spherical dielectric surface. The measured radiation patterns at 246 GHz and Gaussian-beam coupling efficiencies show good agreement with theory. The theoretical results are presented in terms of extension-length/radius and radius/ lambda , and therefore result in universal design curves for silicon lenses of different diameters and at different frequencies. The theoretical and experimental results indicate that for single units, there exists a wide range of extension lengths which result in high Gaussian-coupling efficiencies (50-60%) to moderately high f 's. These Gaussian-coupling efficiencies can be increased to 80-90 degrees % with the use of a lambda /sub m//4 matching-cap layer. For imaging array applications with high packing densities, an extension-length/radius of 0.38 to 0.39 (depending on frequency) will result in peak directivity and a corresponding Gaussian-coupling efficiency 15-20% lower than for single units. >

Radiation properties of a planar antenna on a photonic-crystal substrate

Abstract: The photonic crystal is investigated as a substrate material for planar antennas in the microwave and millimeter-wave bands. Experimental results are presented for a bow-tie antenna on a (111)-oriented face-centered-cubic photonic-crystal substrate with a band gap between approximately 13 and 16 GHz. When driven at 13.2 GHz, the antenna radiates predominantly into the air rather than into the substrate. This suggests that highly efficient planar antennas can be made on photonic-crystal regions fabricated in semiconductor substrates such as GaAs.

Analysis of a wide radiating slot in the ground plane of a microstrip line

Abstract: An analysis of a wide rectangular radiating slot excited by a microstrip line is described Coupled integral equations are formulated to find the electric current distribution on the feed line and the electric field in the aperture The solution is based on the method of moments and using the space domain Sommerfeld-type Green's function The information about the input impedance or reflection coefficient is extracted from the electric current distribution on the microstrip line utilizing the matrix pencil technique The theoretical analysis is described and data are presented and compared with other theoretical and experimental results >

Novel ultrawide-bandwidth Vivaldi antenna with low crosspolarisation

Abstract: The conventional Vivaldi antenna typically has a bandwidth of less than 3:1, limited by the feed line to radiating slot transition. The antipodal Vivaldi antenna removes this limitation but gives very high crosspolarisation which is undesirable for phased array applications. The Letter describes a new balanced antipodal Vivaldi antenna that retains the wide bandwidth characteristics while reducing the crosspolarisation by 15dB across an 18:1 band. Measurements are presented that compare the performance of existing antenna structures with this novel antenna element.

Closed slot antenna having outer and inner magnetic loops

Abstract: An RF identification system having an interrogator operable to send RF interrogations to a transponder and to receive RF responses from the transponder. The interrogator is in electrical communication with a closed slot antenna. The closed slot antenna is formed by an an outer visual magnetic loop and an inner visual magnetic loop such that the antenna has a superior magnetic field when compared to a balanced double loop antenna with an equal area and a superior far-field noise suppression when compared to the single loop antenna. The antenna receives said RF responses from the transponder and provides said RF responses to said interrogator. Other devices, systems and methods are also disclosed.

Differential phase measurement through antenna multiplexing

Abstract: An embodiment of the present invention is a system for time multiplexing a carrier signal received by two or more GPS antennas through a single hardware path, using a single receiver's oscillator in that hardware path as a reference to compare the phase from each antenna. One of the antennas is designated as a reference antenna and a carrier signal received by it is used to phase lock in numerically controlled oscillator. The same carrier signal received by the other antennas is periodically compared in phase to the output of the numerically controlled oscillator. Each comparison results in a phase angle measurement for the respective antennas compared to the master antenna.

Transparent window antenna

Abstract: A slot antenna formed in combination with a vehicle window. An electrically conducting, optically transparent film panel is bonded to the window and terminates so that its outer peripheral edge is spaced from the innermost edge of the metal framing the window to define a polygonal antenna slot between the edges. An unbalanced transmission line is connected to the antenna by connecting the grounded conductor to the framing metal near the metal edge and coupling the ungrounded conductor to the conductive panel near the juxtaposed, interfacing edge of the conductive panel.

Sectorized cellular radio base station antenna

Abstract: A sectorized cellular radio base station antenna is provided comprising: a plurality (e.g. six) of angularly separated directional transmit antennas (11), each transmit antenna having a central access of transmission, for serving mobile units located in sectors centered on the axis of transmission of the transmit antennas; a plurality (e.g. six) of angularly separated directional receive antennas (30), each having a central axis of reception; and diversity combining means for combining signals from adjacent receive antennas. The central axis of the receiving antennas are at an angular offset to the central axis of the transmit antennas and, for a mobile in a given sector served by a given transmit antenna, the diversity combining means are arranged to combine the signals from the two receive antennas the axes of which lie on either side of that transmit antenna axis.

Wide band bunny-ear radiating element

Abstract: A low-cost wideband radiating element for EW (electronic warfare) and radar array antenna applications is reported. This printed end-fire bunny-ear element is fed by a balanced slot line, and it can operate over 0.5 to 18 GHz with very low loss in an isolated environment. The input transition, the feed line, and the launching section of this element are essentially TEM (transverse electromagnetic) structures. The element was scaled and used in an L-band array with 50% instantaneous bandwidth. >

Input impedance of aperture coupled hemispherical dielectric resonator antenna

Abstract: A hemispherical dielectric resonator (DR) antenna fed by a microstripline through an aperture on the ground plane is investigated both theoretically and experimentally. The broadside TE111 mode input impedance of the antenna configuration is evaluated, and reasonable agreement between theory and experiment is obtained. The effects of the slot length and the slot width on the input impedance are studied and discussed.

Tapered slotline antennas at 802 GHz

Abstract: Broken linearly tapered endfire slotline antennas (BLTSAs) were fabricated on 1.7- mu m thin SiO/sub 2/-Si/sub 3/N/sub 4/ dielectric membranes. Antenna patterns in the E-, H-, and D-planes were measured at 802 GHz. The -10 dB beamwidths were found to be approximately 40 degrees in all planes, with side lobe levels below -11 dB (-19 dB in the E-plane). The cross-polarized peaks in the D-plane were 8 dB below the copolarized peak. A theoretical model for calculating the E- and H-plane patterns of tapered slotline antenna 10 is extended to include the co- and cross-polarized D-planes. Measured and calculated patterns show good agreement. >

Self and mutual admittance of slot antennas on a dielectric half-space

Abstract: In this paper, an efficient implementation of the spectral domain moment technique is presented for computing the self and mutual coupling between slot antennas on a dielectric half-space. It is demonstrated that by the proper selection of the weighting functions in the method of moments, the analytic evaluation or simplification of the transverse moment integrals is enabled. This results into a significant reduction of the required computational labor. The method is then utilized in order to provide design data for the self and mutual admittances between two slot antennas on a dielectric substrate lens in the case of fused quartz (∈ r =3.80), crystal quartz (∈ r =4.53), silicon (∈ r =11.9) and GaAs (∈ r =12.8). The presented technique and associated results are useful when designing twin slot quasi-optical receivers, imaging arrays, phased arrays or power-combining arrays of slot elements at millimeter-wave frequencies.

A waveguide transverse slot for array applications

Abstract: The characteristics of a radiating rectangular transverse slot in a rectangular waveguide have been studied. A moment method solution is used with entire basis expansion and testing functions (Galerkin) including the effect of wall thickness. The results are presented in terms of normalized resistance and reactance versus slot length and frequency. Excellent agreement with a previous pulse basis solution is found, as well as with measured data. An array of resonantly spaced transverse slots radiates large grating lobes. A spatial filter using baffles to suppress the grating lobes is described, suppressed. The effect of the baffles on the transverse slot impedance is analyzed for the case of baffles with infinite height. >

Moving vehicle transponder

Abstract: A transponder tag operative in the UHF range and including a substrate of dielectric material having formed on one side a conductive surface providing a ground plane and a dipole antenna, a slot line within the ground plane forming a balanced antenna feeder and leading to the center of the dipole antenna, and the substrate having mounted on the side of the substrate opposite to the one side a transmission line feeder positioned for electromagnetic coupling with the slot line, the transmission line feeder being coupled to transceiver circuit and processing circuit mounted on the opposite side for performing a transponding function.

Aperture coupled microstrip antenna for dual frequency operation

Abstract: An original analysis is presented of an aperture coupled microstrip antenna exhibiting parallel slots on the patch in order to obtain dual frequency operation. The theory is based on the cavity model and the input impedance is calculated using the theorem of energy conservation; the theoretical results are compared with measurements.

Quasi-optical planar arrays with FETs and slots

Abstract: This work describes the design concept and experimental results for prototypes of two-dimensional quasi-optical power-combining arrays. Several different quasi-optical circuits were used to obtain the fundamental data for this study. How to incorporate the antenna input impedance into the active antenna circuit and how to analyze the strong coupling condition with two operating modes are addressed using large-signal analysis. Several circuit configurations are demonstrated, including a single active antenna operating at 9.3 and 24.0 GHz, a six-element linear power-combining array operating at 15.6 GHz, and four-element and sixteen-element two-dimensional power combining arrays operating at 10.4 and 7.8 GHz. Important characteristics such as antenna patterns and tuning ranges are discussed. The prospects for a two-dimensional monolithic quasi-optical power-combining array are discussed. >

Resonance properties of omnidirectional slot doublet in rectangular waveguide

Abstract: A moment method is employed to analyse a longitudinal slot doublet in both air-filled and dielectric-filled rectangular waveguides in which the slot radiators are located in the opposing broadfaces of the waveguide. Theoretical results are presented for the resonance properties of the slot doublet, and these are in good agreement with experimental measurements.

Leaky NRD guide as a feeder for microwave planar antennas

Abstract: Although leaky wave antennas have been studied extensively in the literature, their practical use is still limited. This work proposes a novel and unique application of leaky NRD guides as feeding systems for microwave planar antennas and shows their substantial possibilities of practical use. At first a new leaky waveguide is introduced based on a periodic array of grooves on the upper side of the dielectric strip in the NRD guide. Then, leaky waves issuing from this configuration are used to feed a slot array cut on the upper metal plate of the NRD guide. Design examples of linearly and circularly polarized planar antennas were constructed, and their characteristics were measured at 23 GHz. The obtained results show the validity for this application of the leaky waveguide. >

Theoretical and experimental studies of cavity-backed slot antenna excited by a narrow strip

Abstract: Theoretical and experimental studies of a cavity-backed slot antenna excited internally by a suspended narrow strip are undertaken. Coupled integral equations are developed to compute the electric field distribution in the slot and the surface current distribution on the strip. The input impedance of the cavity at the feeding point on the strip has been computed theoretically and measured experimentally. The impedance data, being a function of cavity dimension, slot length, strip length, and frequency, can be polyfitted and used to implement a systematic design procedure to construct a planar array of these slots. >

Apparatus and method of logging using slot antenna having two nonparallel elements

Abstract: A slot antenna has a square aperture and two current probes at angles to each other in the aperture. The two current probes are excited simultaneously or separately with different signals. By adjusting the amplitude or phase of the signals in the current probes, the angle of the magnetic moment of the antenna can be adjusted. An array of such antennas in an electromagnetic propagation tool for a well-logging device simultaneously provides better standoff performance by adjusting the magnetic moment to be parallel to a borehole axis, and better image response by adjusting the magnetic moment to be perpendicular to the formation bed. The array can be excited to function as an endfire and broadside array of an electromagnetic propagation tool.

Uniform plasma produced by a plane slotted antenna with magnets for electron cyclotron resonance

Abstract: A uniform plasma is produced by a new plane slotted antenna with permanent magnets for the electron cyclotron resonance. The plasma is uniform within a few percent in a diameter of 25–30 cm at a distance of 25–30 cm from the antenna. The plasma density, 1.5×1010 cm−3 with electron temperature of 1.8 eV at a microwave power of 100 W, is almost proportional to the microwave power. A magnetic distribution provided by the magnets is essential for producing such a uniform plasma.

Dual slot-coupled microstrip antenna for dual frequency operation

Abstract: A new dual slot-coupled circular microstrip antenna for dual frequency or dual polarisation operation is proposed. By optimising the placement of the two slots, high isolation between two ports is achieved. Experimentally, an isolation of more than 35dB is obtained at L-band.

A folded slot antenna for planar quasi-optical mixer applications

Abstract: The simple uniplanar quasi-optical mixer uses the effect of orthogonal modes in the folded slot antenna fed by slotline and coplanar waveguide on opposite sides. The input impedance of the antenna is analyzed with the space domain integral equation technique. Experiments at 11 GHz have demonstrated antenna and mixer operation. The antenna shows reasonable radiating properties. By taking advantage of even and odd modes in the antenna, balanced mixing can be achieved with good conversion loss. >

Variable size antenna device having resonance frequency compensation

Abstract: An arm-attached band type radio apparatus capable of providing a stable antenna gain without being affected by the band size has an arm attaching band that is formed into a loop by way of a buckle 31 having an metallic electrode plate 32, first and second conductor plates 5L, 5R, shaped so as to form a slot antenna, to form a loop-like slot antenna. The distal end side of conductor plate 5L has an overlap capacitance changing portion 15 so that, when the connecting position of the band changes according to the thickness of the wearer's arm, the overlap capacitance between first conductor plate 5L and metallic electrode 32, is changed. The magnitude of the capacitance change corresponds to a change in the inductance of the antenna to compensate for a shift in the resonance frequency. The overlap capacitance can be changed by controlling the overlap area or the effective dielectric constant of the material separating conductor plate 5L from metallic electrode 32.

Design procedure for a Fresnel-zone plate antenna

Abstract: A design procedure for two types of Fresnel-zone plate antennas is presented: viz. antennas with absorbing/transparent zones and phase-correcting zones. Design objectives are the optimization of the gain of the lens of the antenna and the side-lobe envelope of its radiation pattern. The design rules are derived from numerical simulations.

A slotted waveguide array using reflection-cancelling slot pairs

Abstract: The slot pair array is compared with the conventional one, and it is pointed out that the new array can realize strong coupling with offset. The slot pair array can radiate a boresite beam. The radiation characteristic of a one-dimensional slot pair array is confirmed experimentally. >

Double-slot antennas on extended hemispherical and elliptical quartz dielectric lenses

Abstract: In this paper, the theoretical far-field patterns and Gaussianbeam coupling efficiencies are investigated for a double-slot antenna placed on quartz hemispherical lenses with varying extension lengths The radiation patterns of the double-slot antenna are computed using ray-tracing inside the lens and electric and magnetic field integration on the spherical dielectric surface The theoretical results are equally valid for double-dipole, log-periodic, and spiral antennas, and are presented in extension length/radius and radius/λ Therefore, the results yield universal design curves for quartz lenses of different diameters and at different frequencies and using different antennas The results indicate that forsingle units, there exists a wide range of extension lengths (ext length/radius=061 to 076) which result in high Gaussian-coupling efficiencies to moderately highf/# systems Forimaging array applications with high packing densities, an extension length/radius=082 to 093 (depending on frequency) will result in peak directivity and highest packing density but lower Gaussian-coupling efficiencies

Method of evaluating a geological formation using a logging tool including slot antenna having two nonparallel elements

Abstract: A slot antenna has a square aperture and two current probes at angles to each other in the aperture. The two current probes are excited simultaneously or separately with different signals. By adjusting the amplitude or phase of the signals in the current probes, the angle of the magnetic moment of the antenna can be adjusted. An array of such antennas in an electromagnetic propagation tool for a well-logging device simultaneously provides better standoff performance by adjusting tile magnetic moment to be parallel to a borehole axis, and better image response by adjusting the magnetic moment to be perpendicular to the formation bed. The array can be excited to function as an endfire and broadside array of an electromagnetic propagation tool.

Radiation characteristics of uniform and nonuniform dielectric leaky-wave antennas

Abstract: An approach based on a waveguide model for analyzing the uniform and nonuniform dielectric leaky-wave structures is proposed for which the Galerkin solution method is applied. In the first part of the paper the far-field radiation of the uniform antenna is determined theoretically and experimentally in the Ku band and also the dependence of beamwidth and sidelobe level as function of strip width and frequency is demonstrated. In addition, an analysis of the antenna with a tapered-strip distribution-is presented. The second part describes a novel tapering procedure, performed by changing the width of the uniform antenna, for obtaining the radiation pattern with lower sidelobe levels. Sinusoidally and exponentially shaped dielectric leaky-wave structures are analyzed as nonuniform antennas. Finally, the radiation and scanning characteristics of these antennas are theoretically presented. >

Quasi-optic amplifier with slot and patch antennas

Abstract: A monolithic quasi-optic amplifier is provided for co-linear beam propagation in the millimeter wave frequency range (30-300 GHz). The amplifier comprises a multiplicity of unit cells that act as nearly independent amplifiers. Each unit cell includes a GaAs transistor, a slot antenna, a patch antenna, a microstrip line, and a DC bias provided by a ground plane that routes non-radiating transmission lines without interference. The slot antennas on GaAs provide preferential directionality in receiving the input waves. A vertically polarized input wave couples energy into each unit cell through the slots in the ground plane, through the microstrip lines, and to the base of each transistor. After amplification by the transistors, the signal is fed to the patch antennas, which generate a horizontally polarized output wave. The size of each patch antenna, which is determined by the operating frequency, is approximately 1 mm by 1 mm in GaAs at 44 GHz.