Showing papers on "Patch antenna published in 1993"

Analysis of a reflectarray antenna using microstrip patches of variable size

Abstract: Microstrip reflectarrays typically use tuning stubs on each element to adjust the phase of the reflected field. The authors describe a new approach in which the need for tuning stubs is eliminated and phase control is achieved simply by adjusting the resonant length of the patch elements. The advantages of this approach are described, as are a full-wave analysis technique for computing the phase of the reflected field as a function of patch size and a design curve giving the change in patch size for a desired reflected field phase shift.< >

Design of wideband circularly polarized aperture-coupled microstrip antennas

Abstract: Two variations of a novel feeding technique for a wideband circularly polarized aperture-coupled microstrip antenna are described. Prototype designs for wideband linearly polarized elements are first presented, and then used for circularly polarized designs. Techniques used for design of the feed network are detailed, for both series feed and parallel feed versions. Experimental results are shown for each antenna, and results for the two designs are compared. The impedance and axial ratio bandwidths for these antennas are among the best yet achieved for microstrip antenna elements. Several design variations are also discussed. >

Folded dipole microstrip antenna

Abstract: A folded dipole microstrip antenna is disclosed herein. The microstrip antenna includes a dielectric substrate for defining a first mounting surface and a second mounting surface substantially parallel thereto. A folded dipole radiative element is mounted on the second mounting surface. The microstrip antenna further includes a microstrip feed line, mounted on the first surface, for exciting the radiative element in response to an excitation signal. In a preferred implementation of the microstrip antenna an excitation signal is applied to the microstrip feed line through a coaxial cable. In such a preferred implementation the folded dipole radiative element includes a continuous dipole arm arranged parallel to first and second dipole arm segments separated by an excitation gap. The feed element is mounted in alignment with the excitation gap and is electrically connected to the continuous dipole arm. The antenna may additionally include a ground plane reflector separated from the folded dipole radiative element by a dielectric spacer for projecting, in a predetermined direction, electromagnetic energy radiated by the folded dipole radiative element. The thickness of the dielectric spacer between the ground plane reflector and the folded dipole radiative element is selected such that the impedance presented by the antenna to the coaxial cable is approximately fifty ohms.

A numerical study of a dielectric disk antenna above grounded dielectric substrate

Abstract: An antenna made of a dielectric disk with a high permittivity mounted on top of a grounded dielectric substrate of low permittivity is analyzed. A numerical procedure based on surface integral equations, derived from the equivalence principle, is used to compute the natural resonant frequencies for the HEM/sub 11/ mode from which the radiation Q factor of the antenna is obtained. Then the radiation pattern of the antenna, operating at the resonant frequency evaluated previously, is computed with an electric dipole excitation located within the dielectric substrate under the dielectric disk. The effect of various parameters on the radiation characteristics of the antenna is studied, and presented in the form of diagrams. The low values of the radiation Q, combined with the high values of the dielectric Q and conductor Q, indicate that this antenna promises to be more efficient then the microstrip 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.

Tuning of microstrip antenna on ferrite substrate

Abstract: The permeability variation of a ferrite substrate with an axial DC magnetic bias field along with the RF excitation of a microstrip antenna leads to multiresonant behavior. A study of tuning the patch antenna on a ferrite substrate to exploit this feature is reported, along with the associated theoretical analysis and experimental findings. >

A half-split cylindrical dielectric resonator antenna using slot-coupling

Abstract: A half-split cylindrical dielectric resonator placed on a metallic plane and excited in its magnetic dipole mode is a potentially useful antenna element. The use of a microstrip line-slot feed scheme for exciting this antenna is reported. Experimental results show that the antenna displays the anticipated radiation pattern and it has a high operating frequency bandwidth (about 10%). The overall antenna configuration can be easily integrated with MICs. >

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. >

Superconducting microstrip antennas: an experimental comparison of two feeding methods

Abstract: The recent discovery of high-temperature superconductors (HTSs) has generated a substantial amount of interest in microstrip antenna applications. However, the high permittivity of substrates compatible with HTS causes difficulty in feeding such antennas because of the high patch edge impedance. Two methods for feeding HTS microstrip antennas at K- and Ka-band are examined. Superconducting microstrip antennas that are directly coupled and gas-coupled to a microstrip transmission line have been designed and fabricated on lanthanum aluminate substrates using Y-Ba-Cu-O superconducting thin films. Measurements from these antennas, including input impedance, bandwidth, efficiency, and patterns, are presented and compared with published models. The measured results demonstrate that usable antennas can be constructed using either of these architectures, although the antennas suffer from narrow bandwidths. In each case, the HTS antenna shows a substantial improvement over an identical antenna made with normal metals. >

Single-layer dual frequency patch antenna

Abstract: A configuration for a slotted patch antenna is introduced which allows two separate operating frequencies Both of these frequencies are associated with a radiating mode almost identical to that of a standard patch The two resonances are related to the patch width and the slot/patch length, respectively

Device for wireless transfer of information

Abstract: A device for wireless transfer of information includes a data carrier in the form of a thin card, and a transponder that receives a first microwave signal, modulates it and codes it with data, and reradiates a second microwave signal without adding new energy thereto. The transponder includes at least one antenna device formed using microstrip conductors. The antenna device includes a patch antenna with an antenna layer that acts against a ground plane where the antenna layer and the ground plane are of substantially equal size. The device is characterized in that, it is equipped with a separate card holder with a reflective surface that is larger than said ground plane. The reflective surface increases the range by reradiating the second microwave signal and reducing sensitivity to back lobe reflections.

Enhanced performance aperture-coupled planar antenna array

Abstract: A flat antenna is disclosed which consists of a substrate having applied thereto an electrically conductive elements, or patches, in a pattern and a metal layer having a slot pattern aligned with the patches, as well as a distribution network mounted on both sides thereof a layer of foamed material. The antenna further includes a reflector consisting of a metal plate. The external surface of the antenna, consisting of a glass substrate surface, can easily be cleaned. Such an antenna can be manufactured inexpensively by using glass and a foamed material. The various patch patterns can be created by screen printing or metallization. The propagation pattern may be shaped as desired the antenna constructed according to the present invention.

Raised patch antenna

Abstract: A raised patch antenna is disclosed which includes a base having a ground plane, a plurality of leg supports interconnected to and extending upwardly to the base, a raised patch antenna element supportedly interconnected to the leg supports and positioned over the ground plane and an RF feed comprising a feed-leg portion provided on the leg supports and a feed base portion provided as a part of the base. The RF feed includes impedance matching components for matching the impedance of the feed base portion with the impedance with the raised patch antenna element in series with the feed-leg portion. The feed-leg portion comprises at least a first pair of balanced feed-leg lines interconnected to opposing sides of the raised patch antenna element. Baluns can be provided in said feed base portion for balancing. For circularly polarized applications, a second pair of balance feed-leg lines are interconnected to second opposing sides of the raised patch antenna element for excitation of orthogonal modes, and a phasing means is provided in the feed base portion for achieving phase quadrature. The antenna yields broad overhead coverage and satisfactory bandwidth, and can be economically and readily produced.

Laminar microstrip patch antenna

Abstract: A laminar microstrip patch antenna includes a ground plane dement having opposing first and second faces, a first dielectric planar member adjacent a first face of the ground plane element, a patch radiator on a face of the first dielectric member remote from said ground element, a second dielectric planar member adjacent a second face of the ground plane element, and a transmission line circuit for feeding the antenna. The transmission line circuit is located on a face of the second dielectric member remote from said ground plane element, and the ground plane has an aperture to couple the transmission line circuit to the patch radiator. The aperture is formed as a cross made up of two intersecting linear slots. The transmission line circuit is formed by two linear conductors intersecting each other at a single electrically insulated point, the intersection point being aligned with a center of the intersection of the aperture cross with the linear conductors lying between the slots of the aperture.

Resonance of a rectangular microstrip patch on a uniaxial substrate

Abstract: Effects of uniaxial anisotropy in the substrate on the complex resonant frequency of the microstrip patch antenna are investigated in terms of an integral equation formulation. The complex resonant frequency of the microstrip patch antenna is calculated using Galerkin's method to solve the integral equation. The sinusoidal functions that are selected as the basis functions, which show fast numerical convergence. Numerical results indicate that both the resonant frequency and the half-power bandwidth are increased due to positive uniaxial anisotropy and decreased due to negative uniaxial anisotropy. >

Input impedance of coaxially fed rectangular microstrip antenna on electrically thick substrate

Abstract: A full-wave spectral domain analysis has been used to obtain input-impedance results for a probe-fed rectangular-patch antenna, modeling the source as a magnetic-current frill. Multiple modes are used in the probe surface current to account for axial and azimuthal variations. It is established that maximum resistance is dependent on the substrate loss tangent. The axial variation of the probe current must be taken into account for substrate thicknesses greater than about 0.02 wavelengths.

Dielectric resonator antenna with wide bandwidth

Abstract: The invention relates to a dielectric resonator antenna system which exhibits an unusually wide bandwidth. This is achieved by chosing a patch antenna/dielectric resonator combination with shape and dimensions such that resonance modes over a continuous range wavelengths can be established therein. The bandwidth and transmission properties of the device are further improved by including a dielectric coupling element (between the dielectric resonator and air) whose antireflection characteristics are optimized for a wavelength which is slightly different from the maximum wavelength of the patch antenna.

Comparison of three series fed microstrip array geometries

Abstract: The authors describe three different design approaches for series-fed broadside microstrip arrays having a center feed point. The first array uses a standard standing-wave feed design, but with the novel feature that the patch width is varied in order to obtain the desired amplitude taper. The second design also uses patches of varying widths, but the main feed line is designed to be matched at each patch tap point. The third array uses a center-fed feed network with each half of the array designed as a traveling-wave array with a main beam angle slightly off broadside. As a comparative example, the authors have designed and tested a 16-element array with a 22-dB sidelobe level for each of the above designs. Patterns, bandwidth, gain, and directivity have been compared for the three designs. >

A new stacked microstrip antenna with large bandwidth and high gain

Abstract: A novel radiating element is presented which can provide simultaneously a large bandwidth and high gain. It consists of four identical patches uniformly displayed within a rectangular aperture (2*2), and fed electromagnetically by a driven patch etched on a lower substrate. It is shown that a good coupling with the parasitic patches is obtained, causing a large bandwidth, and that the resonance modes of each patch are excited in phase, giving a high gain. Its structural simplicity and superior performance make this element an attractive candidate for large phase arrays. >

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.

Extendable antenna for a radio transceiver

Abstract: This extendable antenna is related to an extendable antenna for a portable radio transceiver. The antenna has a first antenna portion and a second antenna portion connected with a connecting portion of the first antenna portion. The first antenna has a loading coil which is enclosed in a top end cap. When the second antenna portion is retracted into a housing, the connecting portion is held by a holding member disposed in the top of the housing, and the connecting portion is ellectrically connected with the circuitry of the transceiver via the holding member. Furthermore, the electrical length of the loading coil is a quarter wavelength, while the physical length of the loading coil is much less than a quarter wavelength. Accordingly, even if the top end cap is only located out of the housing, the first antenna portion detects a radio frequency signal. Furthermore it is unnecessary for the radio transceiver to have an inner antenna and a rod antenna, and switching means for switching from the rod antenna to the inner antenna. And it is unnecessary for the housing to have space for the the inner antenna.

Hybrid antenna including a dielectric lens and planar feed

Abstract: A hybrid antenna including a dielectric lens-antenna in the shape of an extended hemispherical dielectric lens than is operated in the diffraction limited regime. The dielectric lens-antenna is fed by a planar-structure antenna. The planar antenna is mounted on the flat side of the dielectric lens-antenna, using it as a substrate. An optimum extension distance is found experimentally and numerically for which excellent beam patterns and simultaneously high aperture efficiencies can be achieved. The hybrid antenna is diffraction limited, space efficient in an array due to its high aperture efficiency, and is easily mass produced, thus being well suited for focal place receiver arrays.

Resonance in a superstrate-loaded rectangular microstrip structure

Abstract: The complex resonant frequency of a superstrate-loaded rectangular microstrip structure is investigated. The study is performed by using a full-wave analysis and Galerkin's moment method. The numerical convergence using sinusoidal basis functions, with and without considering the edge singularity to expand the unknown surface current distribution on the rectangular patch, is discussed. Numerical results for the effects of superstrate permittivity and thickness on the complex resonant frequency of the rectangular microstrip structure are also presented. >

Crossed-slot antenna having infinite balun feed means

Abstract: A crossed-slot antenna having a reduced number of feed components to achieve circular polarization. The present invention provides a crossed-slot antenna capable of transceiving circularly polarized radiation and having a feed network comprising a ninety degree hybrid and at least one infinite balun. In one embodiment, a transmission line is used to feed a pair of antenna patch elements, one of which acts as a local ground plane for the microstrip line, thereby defining an infinite balun. The transmission line may comprise a microstrip line, the inner conductor of a coaxial cable, or a coplanar waveguide.

Antenna assembly for a portable transceiver

Abstract: An antenna assembly for use with a portable transceiver provides improved communication between the portable transceiver and a base station. A novel antenna assembly is created wherein the radiating portion is elevated above the handset by combining a half wavelength sleeve dipole antenna with a coaxial line section followed by a quarter wavelength choke. Such a configuration reduces the antenna-housing interaction. The quarter wavelength choke prevents the coaxial transmission line from radiating RF energy, and therefore limits the radiation to the sleeve dipole portion of the antenna assembly.

Antenna system having a plurality of dipole antennas configured from one piece of material

Abstract: An antenna system comprises at least two dipole antennas (6) constituting an antenna module and is placed above and parallel with a common, artificial ground plane (5) in the form of an electrically conducting plate, for instance the bottom of a metal box (2). The dipoles (7) and the feed lines (8, 9, 10, 11) are designed as air dielectric strip-lines and are configured in one piece of a homogeneous material and extend mechanically and electrically in an uninterrupted manner from the dipoles to the antenna connector. The parts configured in one piece are produced by punching out sheet metal, and after suitable bending the parts are inserted in corresponding openings (16) in the ground plane (5).

Active inverted stripline circular patch antennas for spatial power combining

Abstract: An active antenna configuration is proposed for spatial-power-combining applications. The active patch antenna uses an inverted stripline topology to take advantage of several features. These features include avoiding drilling through the circuit substrate to insert the diode and the use of air within the resonant cavity to reduce loss. The inverted substrate serves as a radome for hermetic sealing. The active antenna and housing can be fabricated in modular form for reduced cost and easy replaceability of devices. The active inverted stripline patch antenna exhibits a much cleaner spectrum and greater stability than previously reported active antennas. The fixture serves as a ground plane, heat sink, and support in an active planar array or as a mirror in a quasi-optical power-combining resonator. A single active antenna operating at 9.23 GHz exhibited a 16-MHz locking bandwidth at 30-dB locking gain. Power-combining efficiencies of over 89% have been demonstrated for a four-element square array that maintained injection-locking and power-combining over a 60-MHz bias tuned bandwidth. Similarly, a four-element diamond array showed over 86% combining efficiency and 50-MHz bias tuned bandwidth. Beam steering was demonstrated by varying bias voltage to the individual antenna elements of the square array. >

Apparatus and method for tuning embedded antenna

Abstract: An apparatus and method for tuning a multi-radiating element embedded microstrip antenna is disclosed. In one embodiment, the lower resonant frequency of an antenna is tuned using trimmable tabs integral with an upper radiating element and/or scrapable recessed edges on the ground plane surrounding the upper element and/or trimmable tabs interconnected with the ground means and extending inwardly towards the upper element.

Microstrip patch antenna with embedded detector

Abstract: A diode detector is integrated into a microstrip patch antenna. Tuning and matching of the detector are accomplished by adjusting the geometry of the patch. Cost, power consumption, losses, and spurious responses are reduced. The antenna may be adapted to a mixer, video detector, i.f. detector, or audio detector.