Showing papers on "Antenna (radio) published in 1995"

Radio frequency circuit and memory in thin flexible package

Abstract: The present invention is a novel thin and flexible radio frequency (RF) tag that comprises a semiconductor circuit that has logic, memory, and radio frequency circuits, connected to an antenna with all interconnections placed on a single plane of wiring without crossovers. The elements of the package (substrate, antenna, and laminated covers) are flexible. The elements of the package are all thin. The tag is thin and flexible, enabling a unique range of applications including: RF ID tagging of credit cards, passports, admission tickets, and postage stamps.

EM interaction of handset antennas and a human in personal communications

Abstract: In personal communications, the electromagnetic interaction between handset-mounted antennas and the nearby biological tissue is a key consideration. This paper presents a thorough investigation of this antenna-tissue interaction using the finite-difference time-domain (FDTD) electromagnetic simulation approach with detailed models of real-life antennas on a transceiver handset. The monopole, side-mounted planar inverted F, top-mounted bent inverted F, and back-mounted planar inverted F antennas are selected as representative examples of external and internal configurations. Detailed models of the human head and hand are implemented to investigate the effects of the tissue location and physical model on the antenna performance. Experimental results are provided which support the computationally obtained conclusions. The specific absorption rate (SAR) in the tissue is examined for several different antenna/handset configurations. It is found that for a head-handset separation of 2 cm, the SAR in the head has a peak value between 0.9 and 3.8 mW/g and an average value between 0.06 and 0.10 mW/g for 1 W of power delivered to the antenna. Additionally, the head and hand absorb between 48 and 68% of the power delivered to the antenna. >

Small microstrip patch antenna

Abstract: As stated in Chapter 1, one of the many advantages of microstrip patch technology over its competitors is its low profile and hence small volume. Another key advantage of this printed antenna is the relative ease in which it can be connected to the feed network, as was highlighted in Chapter 2. For these reasons antenna design engineers deduced that microstrip patch antennas could be utilized for applications requiring where there was very limited space to mount the antenna. One such global application is for wireless communication handset terminals.

Remote antenna driver for a radio telephony system

Abstract: A multichannel radiotelephony system provides two way cordless communications with a plurality of multichannel transceivers portable within a coverage area comprised by a plurality of cells, each associated with a base station and antennas, such as to permit channel frequency reuse in cells within the coverage area. For at least part of the coverage area, the locations of the antennas within the cells and the locations of the base stations are independently mapped, the antennas being associated with active antenna systems and the active antenna systems being connected to the base stations utilizing broadband transmission by means of a fixed bi-directional signal distribution network. The network is connected to the base stations and the antenna systems through suitable interfaces incorporating frequency translation so that available frequency bands in the signal distribution network which will normally be shared with other services, may be utilised. Plural base stations may be co-located. The radio link to the transceivers may be frequency or time division multiplexed, but communication over the network will normally be frequency multiplexed, using separate bands for transmission and reception.

Spherical antenna pattern(s) from antenna(s) arranged in a two-dimensional plane for use in RFID tags and labels

Abstract: The present invention introduces an RFID system that comprises a two-dimensional antenna configuration having a dipole in combination with a loop antenna or a second dipole with their dipole axes at approximately a 90° angle to one another The pattern of two dipole antennas combined with the pattern of a single loop antenna, allows the sequential combination of the patterns to represent a nearly spherical antenna pattern in three dimensions, while the antennas reside in a two-dimensional plane The presence of multiple antennas also allows for a method to switch among the multiple antennas to find the antenna or combination of antennas that create(s) the strongest RF communication link thereby enabling more efficient transmitted power or more directional reception coverage Improving efficiency can be further improved by taking this concept one step further by adding multiple antennas into the interrogator unit Now the possibility exists whereby the best RF communication possible can be established between the interrogator and transceiver units by switching to the best antenna combination that would most efficiently pass an RF signal between the interrogator and the transceiver before and after which any of the antennas are now free to be used for trickle charging the chargeable battery cell(s) that reside in the transceiver unit

Radiation shielding and range extending antenna assembly

Abstract: A hand-held radio telephone for communication through an orbiting satellite is provided. An antenna assembly is fixed to the hand-held radio telephone and includes a radiation absorber defining an open curved shape in cross section, so as to define an open transmission area. An antenna is disposed adjacent to the open transmission area so that during use of the hand-held radio telephone some of the radiation signal emitted from the antenna is absorbed by the radiation absorber. The radiation signal that is not absorbed by the radiation absorber is transmitted through the open transmission area for reception by a remote receiver, such as an orbiting satellite. At least one parasitic radiation redirection element receives radiation emitted from the antenna. The radiation received by the parasitic radiation redirection element is directed toward the open transmission area, so as to extend a transmission range of the antenna assembly, and thus extend the transmission range of the hand-held radio telephone. By this construction, at least some of the radiation signal that is emitted from the antenna in directions toward the user is blocked by the radiation absorber from being transmitted to the user. Thus, in accordance with the present invention, the inventive hand-held radio telephone has an antenna assembly capable of preventing unwanted exposure of the user to potentially harmful radiation, while providing an enhanced and extended transmission signal to enable improved communication.

Real-time wideband holographic surveillance system

Abstract: A wideband holographic surveillance system including a transceiver for generating a plurality of electromagnetic waves; antenna for transmitting the electromagnetic waves toward a target at a plurality of predetermined positions in space; the transceiver also receiving and converting electromagnetic waves reflected from the target to electrical signals at a plurality of predetermined positions in space; a computer for processing the electrical signals to obtain signals corresponding to a holographic reconstruction of the target; and a display for displaying the processed information to determine nature of the target. The computer has instructions to apply a three dimensional backward wave algorithm.

Broadband patch antennas

Abstract: Part 1 General background: microstrip structures waves on microstrips microstrip lines significant advantages main design problems. Part 2 Microstrip antennas: patch resonators antenna feeds simple models broadbanding. Part 3 SSFIP principle: description of structure material properties design principles examples of realization. Part 4 Theoretical developments: Maxwell's equations potentials and wave equations free space Green's function boundary conditions stratified Green's function method of moments mixed potential integral equation finite size antenna. Part 5 Dual polarization antennas: definitions scattering matrix dual polarization circular polarization. Part 6 Antenna arrays: periodic arrays broadside arrays shaped beams. Part 7 Fabrication techniques: the substrate metallization photolithographic process feed layout design. Part 8 Measurement techniques: circuit measurements antenna measurements substrate properties near fields.

Vehicle global positioning system

Abstract: A vehicle global positioning system includes a mirror assembly having a reflective element and a housing for the reflective element that is made from a material that is electrically substantially non-conducting. The system further includes a global positioning system (GPS) receiver and control module and at least one receiving antenna. The vehicle GPS is adapted to receive earth satellite signals with the receiving antenna and to convert the signals to location, velocity and/or time parameters. The GPS receiving antenna is positioned within the housing of the mirror assembly. In a preferred embodiment, the GPS receiving antenna is positioned within the housing of a vehicle exterior mirror. The vehicle GPS may include a plurality of GPS receiving antennas, such as one located in the vehicle's driver side exterior mirror and the other located in the vehicle's passenger side exterior mirror.

Spectrally efficient high capacity wireless communication systems

Abstract: A wireless system includes a network of base stations (1) for receiving uplink signals transmitted from a plurality of remote terminals (69) and for transmitting downlink signals to the remote terminals. Each base station (1) includes a plurality of transmitting antenna elements (18) for transmitting downlink signals and receiving antenna elements (19) for receiving uplink signals, a signal processor (13) connected to the antenna elements for determining spatial signatures and multiplexing and demultiplexing functions. A multiple base station controller (66) is used for optimizing network performance.

The spectrum efficiency of a base station antenna array system for spatially selective transmission

Abstract: In this paper we investigate the spectrum efficiency gain using transmitting antenna arrays at the base stations of a mobile cellular network. The proposed system estimates the angular positions of the mobiles from the received data, and allows multiple mobiles to be allocated to the same channel within a cell. This is possible by applying a transmit scheme which directs nulls against co-channel users within the cell. It is shown that multiple mobiles per cell is an efficient way of increasing capacity in comparison with reduced channel reuse distance and narrow beams (without directed nulls). The effect of the spatial spread angle of the locally scattered rays in the vicinity of the mobile is also investigated. >

Compact microwave and millimeter wave radar

Abstract: Compact microwave and millimeter wave radars operating at 77 GHz and having resolution of no less than 3.2 meters at a distance of 100 meters. The exemplary dimensions of the radars are 145 millimeters in diameter and 100 or 85 millimeters long. The antenna of the radars employs folded optic design, with the actual focal length of the radar being less than that of the lens in the antenna alone.

Geodesy using the Global Positioning System: The effects of signal scattering on estimates of site position

Abstract: Analysis of Global Positioning System (GPS) data from two sites separated by a horizontal distance of only ∼2.2 m yielded phase residuals exhibiting a systematic elevation angle dependence. One of the two GPS antennas was mounted on an ∼1-m-high concrete pillar, and the other was mounted on a standard wooden tripod. We performed elevation angle cutoff tests with these data and established that the estimate of the vertical coordinate of site position was sensitive to the minimum elevation angle (elevation cutoff) of the data analyzed. For example, the estimate of the vertical coordinate of site position changed by 9.7±0.8 mm when the minimum elevation angle was increased from 10° to 25°. We performed simulations based on a simple (ray tracing) multipath model with a single horizontal reflector which demonstrated that the results from the elevation angle cutoff tests and the pattern of the residuals versus elevation angle could be qualitatively reproduced if the reflector were located 0.1–0.2 m beneath the antenna phase center. We therefore hypothesized that the elevation-angle-dependent error was caused by scattering from the horizontal surface of the pillar, located a distance of ∼0.2 m beneath the antenna phase center. We tested this hypothesis by placing microwave absorbing material between the antenna and the pillar in a number of configurations and by analyzing the changes in apparent position of the antenna. The results indicate that (1) the horizontal surface of the pillar is indeed the main scatterer, (2) both the concrete and the metal plate embedded in the pillar are significant sources of scattering, and (3) the scattering can be reduced greatly by the use of microwave absorbing materials. These results have significant implications for the accuracy of global GPS geodetic tracking networks which use pillar-antenna configurations identical or similar to the one used for this study at the Westford WFRD GPS site.

Multiple access cellular communication with dynamic slot allocation and reduced co-channel interference

Abstract: An apparatus and method reduces co-channel interference in multiple-access cellular communication systems in which frame time or frequency slots are allocated between uplink and downlink. An omnidirectional antenna or a set of directional antennas are used in each cell base station to communicate with users. The frame slots (710,715,720) in which the antennas communicate uplink and downlink information are arranged in accordance with a predetermined frame organization to reduce mixed co-channel interference (CCI). Mixed CCI occurs when a downlink transmission from one base station antenna in a given cell interferes with uplink reception in another base station antenna in a frequency reuse (FR) cell. A potentially-interfering antenna in a given cell is therefore directed to transmit downlink information in a different portion of the frame than that in which a potentially-interfered-with antenna in the frequency reuse cell receives uplink information. The frame slots may be allocated such that only a portion (720) of the available slots are dynamically allocated in accordance with user demand, while the remaining portions are assigned to either uplink (710) or downlink (715) communication.

Micro-patch antenna connected to circuits chips

Abstract: An antenna apparatus comprises: a first chip having: a substrate; a ground film on the substrate; a dielectric film on the ground film; a micro-patch antenna on the dielectric film; a microstrip line extending from the micro-patch antenna; and an in/output microstrip line on the dielectric film; a second chip having a circuit for effecting an operation with the antenna; and a connecting portion for fixing the second chip to the first chip by providing mechanical and electrical connection (flip-chip bonding) between the circuit and the microstrip line and between the circuit and the in/output microstrip line. The substrate comprises a silicon, a GaAs substrate, or a dielectric substrate. The antenna may be provided on the bottom surface of the substrate and be provided on a third substrate also connected by the flip-chip bonding wherein the second chip and the antenna is connected using a through hole. Instead of the through hole, the antenna is coupled to the circuit portion electromagnetically. The substrate may have a hollow portion and the second chip may be accommodated in the hollow portion and the antenna may be provided on a third chip covering the second chip.

Steerable ablation catheter system

Abstract: An antenna assembly has an energy propagating region that is encapsulated in a material having a high dielectric constant for minimizing the loss of energy while having a high thermal conductivity for dissipating conductive heat patterns about the energy propagating region.

Joint detection with coherent receiver antenna diversity in CDMA mobile radio systems

Abstract: In code division multiple access (CDMA) mobile radio systems, both intersymbol interference and multiple access interference arise which can be combated by using either elaborate optimum or favorable suboptimum joint detection (JD) techniques. Furthermore, the time variation of the radio channels leads to degradations of the receiver performance. These degradations can be reduced by applying diversity techniques. Using coherent receiver antenna diversity (CRAD) is especially attractive because only the signal processing at the receiver must be modified. In the present paper, the application of CRAD to the more critical uplink of CDMA mobile radio systems with suboptimum JD techniques is investigated for maximal-ratio combining. The authors study six different suboptimum JD techniques based on decorrelating matched filtering, Gauss-Markov estimation, and minimum mean square error estimation with and without decision feedback. These six suboptimum JD techniques which are well-known for single antenna receivers are extended for the application to CRAD. A main concern of the paper is the determining of the SNR performance of the presented JD techniques for CRAD and the achievable average uncoded bit error probabilities for the transmission over rural area, typical urban and bad urban mobile radio channels are determined.

High sensitivity gravitational wave antenna with parametric transducer readout.

Abstract: A high- $Q$ niobium resonant mass gravitational radiation antenna with a superconducting parametric transducer and noncontacting readout is shown to achieve a noise temperature of about 2 mK using a zero order predictor filter. The predicted intrinsic cold damping of a parametric transducer is confirmed, along with predicted backaction limits on the sensitivity. While the antenna has the highest intrinsic $Q$ factor and lowest noise temperature ever observed in a full scale antenna, the possibility of further improvements is demonstrated.

A blind adaptive transmit antenna algorithm for wireless communication

Abstract: A method is proposed for forming an adaptive phased array transmission beam pattern at a base station without any knowledge of array geometry, path angles or mobile feedback. Estimates of receive vector channels are used to form a transmit weight vector optimization problem. The authors provide closed form solutions for both the single user case and the multiple user case. They show through simulation of a multiple user cellular network that the cooperative transmission network algorithm is capable of improving network frequency re-use capacity by a factor of 5 to 8.

Adaptive antenna matching.

Abstract: In a mobile radio telephone, an adaptive impedance matching circuit (25) is positioned between a transmitting power amplifier (24) and a duplexer (18). The adaptive matching circuit (25) matches an antenna (17) to associated electronic circuitry, thereby optimising power transfer in an effort to maintain communication with a base station and to minimise power dissipation within the device itself. An adaptation algorithm is selected and implemented during idle periods when a reflection coefficient is identified as being large. The reactance of a passive pi network is incrementally modified and settings which achieve an optimum match are stored for subsequent use.

The Polar Plasma Wave Instrument

Abstract: The Plasma Wave Instrument on the Polar spacecraft is designed to provide measurements of plasma waves in the Earth's polar regions over the frequency range from 0.1 Hz to 800 kHz. Three orthogonal electric dipole antennas are used to detect electric fields, two in the spin plane and one aligned along the spacecraft spin axis. A magnetic loop antenna and a triaxial magnetic search coil antenna are used to detect magnetic fields. Signals from these antennas are processed by five receiver systems: a wideband receiver, a high-frequency waveform receiver, a low-frequency waveform receiver, two multichannel analyzers; and a pair of sweep frequency receivers. Compared to previous plasma wave instruments, the Polar plasma wave instrument has several new capabilities. These include (1) an expanded frequency range to improve coverage of both low- and high-frequency wave phenomena, (2) the ability to simultaneously capture signals from six orthogonal electric and magnetic field sensors, and (3) a digital wideband receiver with up to 8-bit resolution and sample rates as high as 249k samples s(exp -1).

Planar antenna array and associated microstrip radiating element

Abstract: The invention relates to radio technology, more specifically to strip antenna arrays used for the direct reception of satellite television broadcasts. The problem addressed by the invention is that of producing a simple, reliable and efficient planar antenna array for receiving signals of differing polarisations, and of producing a microstrip radiating element with double circular polarisation which is highly efficient across a broad frequency band. The proposed planar antenna array is designed as a multiple-layer structure consisting of the following elements arranged one below the other: a dielectric cover (1) with reflecting elements on its inner surface; a conductive layer (5) with a plurality of radiating apertures (4); a dielectric sheet (9) on which are arranged exciter elements and two power circuits for the reception/transmission of signals of differing polarisation; and a screen layer (7). The planar antenna array is also provided with an output waveguide arranged centrally, with two pairs of output probes configured at a right angle in the waveguide cross-section. The proposed microstrip radiating element consists of the following elements arranged one below the other: a conductive layer with radiating aperture; a dielectric sheet on which is mounted an exciter element; and a screen layer. The exciter element is formed by two probes configured at a right angle, a loop arranged on the line bisecting the right angle between the probes, and the conductive region situated at a distance from the point of intersection of the probe axes.

Transmit-receive module for a means of transportation

Abstract: A communication module for a means of transportation such as an automobile, a vessel or the like, the communication module being disposed on a back side or inside of an identification plate of the means of transportation. The communication module is formed of a millimeter wave integrated circuit section and a plane antenna section. The millimeter wave integrated circuit section has two conductive plates arranged on a parallel with each other, and a dielectric stripline and an electric element disposed between the conductive plates. The plane antenna section has two conductive plates arranged on a parallel with each other, a dielectric stripline disposed between the conductive plates and a slot made in one of the conductive plates. At least respective one of the conductive plates of the millimeter wave integrated circuit section and the conductive plates of the plane antenna section are integrated in a plane. The identification plate is made of a material which transmits a millimeter wave with a small loss, for example, polycarbonate, polybutylene terephtalate, polypropyrene reinforced with glass fiber, ABS resin or the like.

Multiple beam antenna system for simultaneously receiving multiple satellite signals

Abstract: A multiple beam array antenna system including a first group of right-handed circularly polarized subarrays and a second group of left-handed circularly polarized subarrays. Combined signals from the right-handed subarrays are output via low noise amplifiers to a first electromagnetic lens while the outputs of the left-handed circularly polarized subarrays are sent via low noise amplifiers to a second steering electromagnetic lens. A satellite selection matrix output block allows a user to tap into signals from right-handed circularly polarized satellites, left-handed circularly polarized satellites, and linearly polarized satellites. A plurality of satellites (e.g. right-handed satellite "A" and linearly polarized satellite "B") may be accessed simultaneously thus allowing the user to utilize both signals at the same time.

An antenna feed network arrangement

Abstract: The present invention relates to antenna arrays and in particular relates to the problems associated with the downtilting of a beam. The present invention provides a linear antenna array comprising a number of radiating elements and a feed network, wherein the feed network is operable to apply the cumulative effect of a progressive phase shift to antenna elements across the array and a stepped complex operator shift to selected groups of antenna elements of the array, whereby a downtilted and null-free coverage by a resulting radiation pattern can thereby be provided. A method of operation is also disclosed.

Theory and experiment of an aperture-coupled hemispherical dielectric resonator antenna

Abstract: A hemispherical dielectric resonator (DR) antenna using aperture coupling for excitation is studied both theoretically and experimentally. The reciprocity method is used to formulate the problem. The exact magnetic field Green's function due to the equivalent magnetic current in the slot is derived rigorously, and it is presented in a form which can be evaluated very efficiently. Moment method is used to solve the magnetic current from which the input impedance of the antenna configuration is obtained. The equivalent radius of the slot is used so that simple formulae developed for the cylindrical dipole can be applied directly. The effects of the slot's length, the slot's position, and the slot's width on the broadside TE/sub 111/ mode input impedance are studied, and reasonable agreement between theory and experiment is obtained. >

Automatic frequency tuning of an RF power source of an inductively coupled plasma reactor

Abstract: A plasma reactor has a reactor chamber for containing a semiconductor wafer to be processed and gas inlet apparatus for introducing an ionizable gas into the chamber, a variable frequency RF power source, an RF antenna near the chamber, the antenna connected to the RF power source for coupling RF power to the ionizable gas to produce a plasma therefrom, a power sensor connected to the antenna for sensing either (or both) transmitted power to the plasma or reflected power to said source, and a control circuit connected to a control input of the variable frequency RF power source and responsive to the power sensor for changing the frequency of the variable frequency RF power source so as to either increase the transmitted power or decrease the reflected power, so as to provide an accurate RF match instantly responsive to changes in plasma impedance.

Radar module for radar system on motor vehicle

Abstract: A FM radar alarm system for use on a motor vehicle detects a following motor vehicle in an adjacent lane behind the motor vehicle. The FM radar alarm system includes an FM radar module including a near-region monitoring antenna and a far-region monitoring antenna. The near-region monitoring antenna radiates a relatively wide radio-wave beam in a near region positioned behind the motor vehicle and extending over an adjacent lane. The far-region monitoring antenna radiates a relatively narrow radio-wave beam in a far region positioned behind the motor vehicle and extending over the adjacent lane.

Direction finding in phased arrays with a neural network beamformer

Abstract: Adaptive neural network processing of phased-array antenna received signals promises to decrease antenna manufacturing and maintenance costs while increasing mission uptime and performance between repair actions. We introduce one such neural network which performs aspects of digital beamforming with imperfectly manufactured, degraded, or failed antenna components. This paper presents measured results achieved with an adaptive radial basis function (ARBF) artificial neural network architecture which learned the single source direction finding (DF) function of an eight-element X-band array having multiple, unknown failures and degradations. We compare the single source DF performance of this ARBF neural network, whose internal weights are computed using a modified gradient descent algorithm, with another radial basis function network, Linnet, whose weights are calculated using linear algebra. Both networks are compared to a traditional DF approach using monopulse.