Showing papers on "Patch antenna published in 1997"
Patent•
03 Nov 1997
TL;DR: In this paper, a volumetric ablation is achieved without impeding out any of the deployed antennas when 5 to 200 watts of electromagnetic energy is delivered from the electromagnetic energy source to the multiple antenna ablation device.
Abstract: A multiple antenna ablation apparatus includes an electromagnetic energy source, a trocar including a distal end, and a hollow lumen extending along a longitudinal axis of the trocar, and a multiple antenna ablation device with three or more antennas. The antennas are initially positioned in the trocar lumen as the trocar is introduced through tissue. At a selected tissue site the antennas are deployable from the trocar lumen in a lateral direction relative to the longitudinal axis. Each of the deployed antennas has an electromagnetic energy delivery surface of sufficient size to, (i) create a volumetric ablation between the deployed antennas, and (ii) the volumetric ablation is achieved without impeding out any of the deployed antennas when 5 to 200 watts of electromagnetic energy is delivered from the electromagnetic energy source to the multiple antenna ablation device. At least one cable couples the multiple antenna ablation device to the electromagnetic energy source.
750 citations
TL;DR: In this paper, a critical overview of possible solutions for dual-frequency patch antennas is presented, and future perspectives are outlined, in particular geometric and spectral properties of patch antennas are discussed.
Abstract: Dual-frequency patch antennas may provide an alternative to large-bandwidth planar antennas, in applications in which large bandwidth is really needed for operating at two separate transmit-receive bands. When the two operating frequencies are far apart, a dual-frequency patch structure can be conceived to avoid the use of separate antennas. In this paper, a critical overview of possible solutions for dual-frequency patch antennas is presented, and future perspectives are outlined. Geometries are discussed in particular.
467 citations
01 Oct 1997
TL;DR: In this paper, the U-slot patch on a foam substrate of about 0.08/spl lambda/thick was designed to attain 20-30% impedance as well as gain bandwidth.
Abstract: Experimental and simulation results are presented on the coaxially fed rectangular patch antenna with a U-shaped slot. Experimental results include impedance bandwidth, copolar- and crosspolar-pattern characteristics and gain measurements. Simulation results are obtained mainly through the development of a FDTD code. It is found that the U-slot patch on a foam substrate of about 0.08/spl lambda/ thick can be designed to attain 20-30% impedance as well as gain bandwidths without the need of parasitic patches on another layer or on the same layer. The far-field patterns have good copolar and crosspolar characteristics. By altering the patch width or feed position, the wideband characteristic can be changed into a dual-frequency characteristic. Simulation results are in good agreement with measurements.
413 citations
TL;DR: In this paper, an antenna can be used to realize a near-field optical probe that combines spatial resolution well below the diffraction limit with transmission efficiency approaching unity, using a planar bow-tie antenna with an open-circuited gap at its apex.
Abstract: We demonstrate that an antenna can be used to realize a near-field optical probe that combines spatial resolution well below the diffraction limit with transmission efficiency approaching unity. The probe consists of a planar bow-tie antenna with an open-circuited gap at its apex. We present proof-of-principle measurements using microwave radiation and discuss scaling the antenna to the visible optical spectrum.
395 citations
TL;DR: In this article, a miniature aperture-coupled microstrip antenna of very high permittivity designed at 1.66 GHz is described, where superstrates of appropriate thickness are added on the substrate for gain enhancement.
Abstract: A miniature aperture-coupled microstrip antenna of very high permittivity designed at 1.66 GHz is described. Superstrates of appropriate thickness are added on the substrate for gain enhancement. Its size is dramatically reduced and the electrical performance remains almost the same as compared with the conventional microstrip antenna of low dielectric constant. Experimental data for the return loss, radiation pattern and measured antenna gain are presented to validate the design.
207 citations
Patent•
12 Nov 1997
TL;DR: In this article, a control system for the antenna selectively connects and isolates RF currents between certain tuning strips and the patch, changing the effective length of the patch and thus the antenna's resonant frequency, thereby frequency tuning the antenna electrically over a relatively broad band of frequencies.
Abstract: A patch antenna is provided with one or more tuning strips spaced therefrom and RF switches to connect or block RF currents therebetween. When a control system for the antenna selectively connects and isolates RF currents between certain of the tuning strips and the patch, the tuning strips change the effective length of the patch and thus the antenna's resonant frequency, thereby frequency tuning the antenna electrically over a relatively broad band of frequencies. The control system includes circuitry for rapidly switching the antenna to a desired frequency with minimal delay and with superior isolation from the antenna, making it suitable for use in DAMA, TDMA, and other frequency hopping applications.
181 citations
Patent•
07 Nov 1997
TL;DR: In this paper, a microstrip patch antenna having reduced size is implemented by providing a substrate having on one surface a conductive fractal pattern, and having on the other surface another conductive pattern that may (but need not) also be a fractal patterns.
Abstract: A microstrip patch antenna having reduced size is implementing by providing a substrate having on one surface a conductive fractal pattern, and having on the other surface a conductive pattern that may (but need not) also be a fractal pattern. The fractal pattern is of order N≧1, and if fractal patterns are formed on each substrate surface, the fractal family and fractal iteration number may be different. So fractalizing at least one conductive surface permits reduction of substrate dimension may be reduced to one-eighth wavelength.
180 citations
TL;DR: In this paper, it was found through a vector integral-equation analysis and the reciprocity theorem that the gain of a microstrip antenna can be greatly enhanced with a photonic band gap material layer either as the substrate or the superstrate.
Abstract: It is found through a vector integral-equation analysis and the reciprocity theorem that the gain of a microstrip antenna can be greatly enhanced with a photonic band-gap material layer either as the substrate or the superstrate. The beam angle is found to coincide with that of a leaky-wave mode of a planar-grating structure. This observation suggests that high gain is due to the excitation of strong leaky-wave fields.
171 citations
Patent•
23 Jun 1997
TL;DR: In this article, a planar phased array antenna with M by N antenna cells with only M+N phase shifters was proposed. But, the phase shifter was used to separate adjacent cells in the matrix by coupling an antenna element to one row and column feed.
Abstract: A new planar phased array antenna is disclosed having M by N antenna cells with only M+N phase shifters A grid of M+N feed lines with the M feed lines at a first frequency having a uniquely controllable phase and N feed lines at a second frequency with each feed line having a uniquely controllable phase are provided separating adjacent cells in the matrix By coupling an antenna element through a mixer to one row and column feed, a phase for each antenna element in the array can be uniquely controlled through a scan, thereby providing a simplified planar array to be implemented as a patch antenna
165 citations
TL;DR: In this article, a chip-resistor-loaded rectangular microstrip antenna fed using a probe feed or an inset microstrip-line feed is presented. But the advantages of small antenna size and wide antenna bandwidth, compared to a conventional rectangular micro-strip antenna, are not discussed.
Abstract: Designs of a chip-resistor-loaded rectangular microstrip antenna fed using a probe feed or an inset microstrip-line feed are presented. These antenna designs have the advantages of small antenna size and wide antenna bandwidth, compared to a conventional rectangular microstrip antenna. Details of the experimental results are given.
149 citations
TL;DR: In this article, the design of a single-feed small microstrip antenna with circular polarisation (CP) radiation is described, which is achieved by cutting slits in the square patch and adjusting the lengths of the slits.
Abstract: The design of a single-feed small microstrip antenna with circular polarisation (CP) radiation is described. This design is achieved by cutting slits in the square patch and. By adjusting the lengths of the slits, the microstrip antenna can perform CP radiation with a reduced patch size at a fixed operating frequency. This design also provides a wide CP bandwidth and relaxed fabrication tolerances.
TL;DR: In this article, the authors presented properties of a circular patch antenna with radiation characteristics similar to those of a resonant monopole, which is easy to match to a 50 /spl Omega/ line.
Abstract: Properties of a circular patch antenna with radiation characteristics similar to those of a resonant monopole are presented. The TM/sub 01/ mode excited patch on a small ground plane radiates a null on boresight and is easy to match to a 50 /spl Omega/ line. Applications include mobile vehicle applications and wireless LANs.
Patent•
20 Mar 1997TL;DR: A tapered antenna structural panel array that can serve both as a structural member and an antenna is made from an injection molded monolithic three dimensional grid of thermoplastic material as discussed by the authors, where the antenna ground plane is supported by the sheet bonded to the lower edge and connected to the antenna circuitry of the sidewalls.
Abstract: A tapered notch antenna structural panel array that can serve both as a structural member and an antenna is made from an injection molded monolithic three dimensional grid of thermoplastic material. The notch and feed line is in the form of microstrip or stripline circuitry formed to the sidewalls of adjacent cells. Dielectric sheets of material are bonded to the upper and lower edges of the grid. Interconnect circuitry on the antenna ground plane is supported by the sheet bonded to the lower edge and connected to the antenna circuitry of the sidewalls.
TL;DR: In this article, a triangular microstrip antenna with dual-frequency operation is presented, where the microstrip patch is shortcircuited using a shorting pin and fed by a single probe feed.
Abstract: This paper presents a novel design of triangular microstrip antenna with dual-frequency operation. In this design the microstrip patch is short-circuited using a shorting pin and fed by a single probe feed. By varying the shorting pin position in the microstrip patch, such a design can provide a large tunable frequency ratio of about 2.5-4.9 for the two operating frequencies. Experimental results for operating at frequencies of 464 and 2276 MHz are presented and discussed.
TL;DR: In this paper, a triangular microstrip antenna with a U-shaped slot was proposed and the performance of the antenna was evaluated with a foam substrate of thickness /spl sim/0.08 /spl lambda/sub 0.
Abstract: The broadband design of a triangular microstrip antenna with a U-shaped slot is demonstrated. With a foam substrate of thickness /spl sim/0.08 /spl lambda//sub 0/, a slotted triangular microstrip antenna with an operating bandwidth of /spl sim/18% is obtained, which is /spl sim/1.8 times that of a corresponding simple triangular patch antenna. Details of the antenna design and experimental results are presented.
TL;DR: In this paper, a numerical modeling based on the solution of coupled integral equations is used for the characterization of CPW-fed aperture-coupled microstrip antennas, such as open stubs, slot loops and capacitively and inductively coupled slots, in terms of return loss and front-to-back radiated power ratio.
Abstract: A numerical modeling based on the solution of coupled integral equations is used for the characterization of CPW-fed aperture-coupled microstrip antennas. Various shapes of excitation slots, such as open stubs, slot loops, and capacitively and inductively coupled slots, are investigated in terms of return loss and front-to-back radiated power ratio. It is shown that a centered CPW open stub gives a minimum of back radiation while allowing for easy matching. The slot-loop excitation seems to be a convenient feeding mechanism that also allows the insertion of active devices.
TL;DR: In this paper, the characteristics of a single-feed dual-frequency compact microstrip antenna with a shorting pin are studied experimentally, which can provide a high frequency ratio of > 3.0 between the two operating frequencies.
Abstract: The characteristics of a single-feed dual-frequency compact microstrip antenna with a shorting pin are studied experimentally. Besides the compactness of the antenna, this dual-frequency design can provide a high frequency ratio of >3.0 between the two operating frequencies. Typical experimental results of the proposed antenna are presented and discussed.
Patent•
07 Nov 1997
TL;DR: In this paper, the first fractal antenna of iteration N≧2 in free space exhibits characteristics including at least one resonant frequency and bandwidth, and a region of ground plane may be formed adjacent the antenna system, to form a sandwich-like system that is readily tuned.
Abstract: A first fractal antenna of iteration N≧2 in free space exhibits characteristics including at least one resonant frequency and bandwidth. Spacing-apart the first fractal conductive element from a conductive element by a distance Δ, non-planarly or otherwise, preferably ≦0.05λ for non-planar separation for frequencies of interest decreases resonant frequency and/or introduces new resonant frequencies, widens the bandwidth, or both, for the resultant antenna system. The conductive element may itself be a fractal antenna, which if rotated relative to the first fractal antenna will alter or tune at least one characteristic of the antenna system. Forming a cut anywhere in the first fractal antenna causes new and different resonant nodes to appear. The antenna system may be tuned by cutting-off a portion of the first fractal antenna, typically increasing resonant frequency. A region of ground plane may be formed adjacent the antenna system, to form a sandwich-like system that is readily tuned. Resonator systems as well as antenna systems may be tuned using is disclosed methodology.
Patent•
05 Dec 1997TL;DR: In this article, a miniaturized and thin slot antenna device maintains high transmitting and receiving performance by improving the configuration of an antenna body and a circuit substrate, which can be constructed from two parallel, opposed, electrically conductive members spaced apart by a gap.
Abstract: A miniaturized and thin slot antenna device maintains high transmitting and receiving performance by improving the configuration of an antenna body and a circuit substrate. The slot antenna device includes an antenna body made of an electrically conductive member having a slot into which the circuit substrate is placed. Alternatively, the slotted, electrically conductive member can be placed flat on a first surface of the circuit substrate, which can contain a reflector on its second, opposite surface. The slot antenna device also can be constructed from two parallel, opposed, electrically conductive members spaced apart by a gap so that a slot is defined by outer peripheries of the electrically conductive members. The electrically conductive members can be provided on opposite surfaces of a circuit substrate.
TL;DR: By using a shorting pin and meandering the circular patch, a compact circular microstrip antenna with a patch size of less than 10% of the conventional circular patch antenna can be easily obtained as discussed by the authors.
Abstract: By using a shorting pin and meandering the circular patch, a compact circular microstrip antenna with a patch size of less than 10% of the conventional circular patch antenna can be easily obtained. The design of such compact circular microstrip antennas is described, and experimental results are presented and discussed. © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 15: 147–49, 1997.
TL;DR: In this paper, a TM/sub 02/-mode circular patch antenna for the application of radio LANs is reported and tested at 5.2 GHz and the antenna pattern is omnidirectional in azimuth and has a notch in the normal direction.
Abstract: A TM/sub 02/-mode circular patch antenna for the application of radio LANs is reported. An experimental prototype operating at 5.2 GHz is designed and tested. The antenna pattern is omnidirectional in azimuth and has a notch in the normal direction. A 3.3% bandwidth of VSWR /spl les/2 and 4.2-dB antenna gain were measured. Experimental results agree well with theoretical predictions.
Patent•
31 Mar 1997TL;DR: In this article, a folded quarter-wave patch antenna with a ground plane separated from the conductor plate by a dielectric substrate and an electrically connected ground plane is connected to the first arm at one end.
Abstract: A folded quarter-wave patch antenna which includes a conductor plate having first and second arms spaced apart. A ground plane is separated from the conductor plate by a dielectric substrate and is approximately parallel to the conductor plate. The ground plane is electrically connected to the first arm at one end. A signal unit is electrically coupled to the first arm. The signal unit transmits and/or receives signals having a selected frequency band. The folded quarter-wave patch antenna can also act as a dual frequency band antenna. In dual frequency band operation, the signal unit provides the antenna with a first signal of a first frequency band and a second signal of a second frequency band.
TL;DR: In this article, two class B GaAs field effect transistor (FET) power amplifiers integrated with patch antennas have been designed and fabricated at 2.48 GHz and an increase of 7% in the power added efficiency (PAE) and 0.5 dB in the output power was achieved through the second harmonic tuning.
Abstract: Two class B GaAs field-effect transistor (FET) power amplifiers integrated with patch antennas have been designed and fabricated at 2.48 GHz. Both amplifiers are integrated with patch antennas, which serve as load and radiator. In one case, a standard patch design was used with random harmonic termination. In another case, a modified patch design was used, which allows the tuning of the second harmonic. In this case the antenna has an additional function of a filter. An increase of 7% in the power-added efficiency (PAE) and 0.5 dB in the output power was achieved through the second harmonic tuning.
13 Jul 1997
TL;DR: In this article, the authors presented a feasibility study on optically transparent patch antennas with microstrip line and probe feeds, which operate at 2.3 GHz and 19.5 GHz respectively.
Abstract: The paper presents a feasibility study on optically transparent patch antennas with microstrip line and probe feeds. The two antennas operate at 2.3 GHz and 19.5 GHz respectively. They are constructed from a thin sheet of clear polyester with an AgHT-8 optically transparent conductive coating. The experimental results show good radiation patterns and input impedance match. The antennas have potential applications in mobile wireless communications.
TL;DR: In this article, a single-feed, reduced-size dual-frequency rectangular microstrip antenna with a cross slot of equal length is presented, where the frequency ratio is mainly determined by the aspect ratio of the rectangular patch, and the reduction in the two operating frequencies is achieved by cutting a cross-slot in the microstrip patch.
Abstract: A new design of single-feed, reduced-size dual-frequency rectangular microstrip antenna with a cross slot of equal length is presented. The frequency ratio of the two operating frequencies is mainly determined by the aspect ratio of the rectangular patch, and the reduction in the two operating frequencies is achieved by cutting a cross slot in the microstrip patch. Details of the experimental results for such a design are presented and discussed.
Patent•
31 May 1997TL;DR: In this article, the antenna design for a tag operating in an radio frequency identification system minimizes the influence of reflecting surfaces upon the antenna radiation pattern by constructing a rectangular metal patch separated from a larger metallic plane.
Abstract: An antenna design for a tag operating in an radio frequency identification system minimizes the influence of reflecting surfaces upon the antenna radiation pattern. The antenna advantageously provides near uniform performance when the tag is in varying proximity to different metal reflecting surfaces. The antenna operates as a quarter wave patch antenna and is constructed from a rectangular metal patch separated from a larger metallic plane. This metallic plane serves as the reference ground plane for a circuit attached to the antenna, with a direct short between the patch and the ground plane along one edge of the patch. The dimensions of the metal patch are selected such that one quarter of a wavelength of incident radiation forms a standing wave on the antenna. A careful choice of dielectric material and lateral dimensions determine the bandwidth of the antenna. The presence of the ground plane serves as a natural advantageous plane of isolation between energy radiated from the patch antenna and otherwise reflecting surfaces which may be brought into proximity with this antenna.
Patent•
04 Feb 1997TL;DR: An aperture-coupled planar inverted-F antenna (PIFA) as mentioned in this paper is a planar PIFA with a radiating patch formed on one side of a ground plane and separated therefrom by a first dielectric which may be air, foam or another suitable material.
Abstract: An aperture-coupled planar inverted-F antenna (PIFA) including a radiating patch formed on one side of a ground plane and separated therefrom by a first dielectric which may be air, foam or another suitable material. A shorting strip connects a side of the radiating patch to the ground plane at a point corresponding to a dominant mode null, such that the size of the radiating patch may be reduced by a factor of two. A microstrip feedline is arranged on an opposite side of the ground plane and separated therefrom by a second dielectric which may be part of a substrate formed of printed wiring board material. Signals are coupled between the microstrip feedline and the radiating patch via an aperture formed in the ground plane. The use of aperture coupling avoids the excessive cost associated with conventional TEM transmission line or coaxial feeds, while providing improved manufacturability and ease of integration relative to PIFAs with conventional feeds. Moreover, the aperture coupling provides improved tuning flexibility. For example, a portion of the microstrip feedline may be used as a tuning stub to provide impedance matching on the feedline.
Patent•
15 Feb 1997
TL;DR: In this paper, a flat three-dimensional antenna is built in three planes, where in the first plane a base plate, in the second plane a slot divider bent in a U-shape, and in the third plane a resonant structure above the slot dividers.
Abstract: A flat three-dimensional antenna is built in three planes. In the first plane is a base plate, in the second plane is a slot divider bent in a U-shape, and in the third plane is resonant structure above the slot divider. The slot divider has a middle part with a length of preferably λ/4 and two limbs of λ/8 of the same length. With the base plate the slot divider forms a λ/2 antenna slot, while the resonant structure with the slot divider defines a shorter second antenna slot. The antenna is characterized by a large bandwidth and omnidirectional radiation characteristic. Perpendicular to the base plate there is essentially no radiation. Feeding takes place preferably via a stripline which is routed between two limbs to a middle part. Impedance matching of the antenna is achieved by suitable dimensioning of the stripline. The antenna can be built equally well in air as well as in a dielectric such as a ceramic block. Several of these antennas can be combined into an ultracompact diversity antenna system.
TL;DR: In this paper, a triangular microstrip antenna with a shorting pin can significantly reduce the antenna size at a given operating frequency, and the experimental results of such a triangulation antenna are presented.
Abstract: Loading a triangular microstrip antenna with a shorting pin can significantly reduce the antenna size at a given operating frequency. Experimental results of such a triangular microstrip antenna are presented. Variations of the resonant frequency of the triangular microstrip patch with different shorting-pin positions are given, and comparisons of the compact and conventional triangular microstrip antennas are also presented and discussed.
TL;DR: In this paper, the mixedpotential integral-equation (MPIE) method is developed in the spatial domain for multilayered media, which is useful for efficient computation for interacting microstrip elements, which may be located at any substrate layer and separated by an arbitrarily large distance.
Abstract: Microstrip elements of arbitrary shape are modeled in multilayered media. The Green's function for the multilayered structure is developed in a form useful for efficient computation for interacting microstrip elements, which may be located at any substrate layer and separated by an arbitrarily large distance. This result is of significant value to a variety of applications in wave propagation besides those discussed in this paper. The mixed-potential integral-equation (MPIE) method is developed in the spatial domain. Examples for regularly/arbitrarily shaped geometries in single and multilayered media are presented. These involve the optimization of an open-end microstrip, a radial-stub microstrip, a five-section overlay-gap-coupled filter, and a circular-patch proximity-coupled microstrip antenna. Very good agreement with measurement and other published data is observed.