Showing papers on "Coaxial antenna published in 2002"

Dominant mode leaky-wave antenna with backfire-to-endfire scanning capability

Abstract: A novel dominant mode leaky-wave antenna is proposed. This antenna is a transmission line structure with radiating wavenumber increasing from negative to positive values, providing backward to forward scanning capability as the frequency is increased. The characteristics and performances of the antenna are demonstrated by full-wave simulation and measurement results.

An electromagnetic bandgap resonator antenna

Abstract: This paper introduces a new explanation of the electromagnetic bandgap (EBG) material properties using the study of the EBG structures in the frequency domain and reciprocal space. Once the behavior of such a material is understood, the properties of the EBG are used in order to make an EBG antenna. The antenna is realized with dielectric EBG rods. Its directivity is increased compared to a simple patch antenna. Such a device allows us to obtain a high gain with a very thin structure.

A built-in, multi band, multi antenna system

Abstract: A build-in, multi band, multi antenna system (1) for a protable communicaiton device (10) has a first antenna (2, 4, 5), which is resonant in first an second frequency band. A secon antenna (3) is resonant in a fourth frequency bank. The first antenna, the papasitic element and the second antenna are provided on a common flexible substrate.

Wireless communication device having multiband antenna

Abstract: The invention provides antenna systems (102, 900, 2300, 2800) for wireless communication devices that make efficient use of space while supporting multi-band operation. The antenna systems comprise elongated flat conductors (206,406,902,1206,1508,1304,1902,2000,2100,2302,2500,2600,2702,2802,2902), supported spaced from finite ground planes (202, 914, 1910). The antenna systems are capable of operating in a symmetric common mode, an anti-symmetric differential mode, and a slot mode.

Antenna with variably tuned parasitic element

Abstract: A multi-band radio communication device with an antenna system that includes an antenna element and a parasitic element located in proximity to the antenna element. A tuning circuit is coupled to the parasitic element. The tuning circuit is variable to adjust the parasitic load on the antenna element to provide variable operating frequencies and bandwidths for the communication device.

Comformal phased array antenna and method for repair

Abstract: A conformal phased array antenna and associated method of repairing the antenna are provided. The antenna has individual subassemblies or line replaceable units such that the antenna can be repaired without completely removing the entire antenna. The antenna generally includes a planar antenna subassembly including an array of RF modules disposed in a reference plane. The antenna also typically has a contoured waveguide subassembly including a contoured aperture honeycomb structure. The contoured aperture honeycomb structure defines a number of passages that are in communication with respective RF modules. The exterior surface of the contoured aperture honeycomb structure that faces away from the planar antenna subassembly is contoured such that at least portions of this surface are at an oblique angle with respect to the reference plane. This contoured surface may advantageously be shaped to match the contour of the surface of the structure to which the antenna is mounted.

Protable radio terminal testing apparatus using single self-complementary antenna

Abstract: A portable radio terminal testing apparatus has an antenna coupler 20, a connecting member 16, and a measuring device 15. The antenna coupler 20 has a placement member 35, a coupling antenna 25, a pair of through-connection portions, and an impedance transformer 31. The placement member 35 accepts a portable radio terminal 1, which is a testing object, in an unrestricted state. The coupling antenna 25 is disposed so as to be electromagnetically coupled with an antenna 19 of the portable radio terminal 1, and has a pair of antenna elements which are formed at one face side of a dielectric substrate 26 and which have a planar antenna structure of a predetermined shape, and a pair of feeding points, and is formed from a self-complementary antenna having a predetermined impedance within an operating frequency range including at least 800 MHz to 2.5 GHz order.

Leaky CPW-based slot antenna arrays for millimeter-wave applications

Abstract: A uniplanar leaky-wave antenna (LWA) suitable for operation at millimeter-wave frequencies is introduced. Both unidirectional and bidirectional versions of the antenna are presented. The proposed structure consists of a coplanar waveguide fed linear array of closely spaced capacitive transverse slots. This configuration results in a fast-wave structure in which the n=0 spatial harmonic radiates in the forward direction. Since the distance, d, between adjacent elements of the array is small d/spl Lt//spl lambda//sub o/, the slot array essentially becomes a uniform LWA. A comprehensive transmission line model is developed based upon the theory of truncated periodic transmission lines to explain the operation of the antenna and provide a tool for its design. Measured and simulated radiation patterns, directivity, gain, and an associated loss budget are presented for a 32-element antenna operating at 30 GHz. The uniplanar nature of the structure makes the antenna appropriate for integration of shunt variable capacitors such as diode or micro-electromechanical system varactors for fixed frequency beam steering at low-bias voltages.

Antenna system having high impedance surface

Abstract: An antenna system for receiving both circularly polarized electromagnetic signals and linearly polarized electromagnetic signals, the circularly polarize signals arriving at the antenna system from a direction normal or oblique to a major surface of the antenna system and the linearly polarized signals arriving at the planar antenna system from a direction acute to said major surface The antenna system includes a high impedance surface and a plurality of antenna elements disposed on said high impedance surface, the plurality antenna elements arranged in a pattern on said surface such first selected ones of said antenna elements are responsive to circular polarization and second selected ones of said antenna elements are responsive to linear polarization

Method and system for improving isolation in radio-frequency antennas

Abstract: In an antenna structure having a transmit antenna disposed over a first section of a ground plane and a receive antenna disposed over a second section of the ground plane, a cut is provided between the first and second sections of the ground plane. The length of the cut is substantially equal to one quarter-wavelength of the operating frequency band of transmit/receive antenna pair so as to provide isolation between the transmit antenna and the receive antenna. If the antenna structure also has a transceiver antenna operated in a further frequency band disposed over the same ground plane and straddling over the first section and the second section, a switch is provided over the cut. The switch is operating in a closed position when the transceiver antenna in the further frequency band is used, and in an open position when the transmit/receiver antenna pair is used.

Investigations into a cavity-backed circular-patch antenna

Abstract: An empirical formula for resonant frequency of a circular cavity-enclosed circular-patch antenna is tested with measured results. The patch miniaturization in the presence of the cavity is proved. Different design curves in terms of resonant frequencies and bandwidth are derived to facilitate antenna design without a priori knowledge of complex numerical techniques. A simple gain formula for a circular-patch antenna is derived and tested against the measured gain data. The results agree very well. The beamwidth, axial ratio, and mutual coupling in the presence of the cavity are investigated.

Fractal antenna ground counterpoise, ground planes, and loading elements and microstrip patch antennas with fractal structure

Abstract: An antenna system includes a fractalized element that may be a ground counterpoise, a top-hat located load assembly, or a microstrip patch antenna having at least one element whose physical shape is at least partially defined as a first or higher iteration deterministic fractal. The resultant fractal element may rely upon an opening angle for performance, and is more compact than non-Euclidean ground counterpoise elements or the like. A vertical antenna system includes a vertical element that may also be a fractal, and a vertical antenna can include vertically spaced-apart fractal conductive and passive elements, and at least one fractal ground element. Various antenna configurations may be fabricated on opposite surfaces of a substrate, including a flexible substrate, and may be tuned by rotating elements relative to each other, and/or by varying the spaced-apart distance therebetween. Fractalized ground counterpoise elements and/or microstrip patch antenna systems may be fabricated on a flexible printed circuit substrate, and/or placed within the support mount of a cellular telephone car antenna.

Novel design of broad-band stacked patch antenna

Abstract: A novel broadband stacked E-shaped patch antenna is proposed in this paper. The proposed antenna has an input impedance bandwidth of about 38.41%, better than the conventional E-shaped microstrip patch antenna, which has an input impedance bandwidth of 33.8%. Through the use of the washer on the probe of the stacked patch antenna, the input impedance bandwidth is improved further to 44.9%. The radiation patterns are found to be relatively constant throughout the whole band. Comparisons of these antennas are presented in this paper.

Miniature microstrip antenna with a partially filled high-permittivity substrate

Abstract: A new technique to reduce the overall dimension of a microstrip antenna using a partially filled high-permittivity substrate is proposed The miniaturized microstrip antenna for a repeater system in a mobile communication cellular band (824-894 MHz) is designed with the proposed technique and manufactured with light weight and small size Comparison between simulations, based on HP HFSS software, and measurements are provided

Printed dual-band dipole antenna with U-slotted arms for 2.4/5.2 GHz WLAN operation

Abstract: Dual-band operation of a printed dipole antenna with U-slotted arms is presented. Due to the embedded U-shaped slots, two additional dipole arms are obtained in the proposed design, which form a second dipole antenna with a smaller length and which can generate a higher resonant mode for the 5.2 GHz band operation. By incorporating the original dipole arms designed for the 2.4 GHz band operation, the proposed antenna can perform WLAN operations in the 2.4 and 5.2 GHz bands.

Printed diversity monopole antenna for WLAN operation

Abstract: A printed diversity monopole antenna for WLAN operation in the 2.4 GHz band is presented. The antenna comprises two orthogonal linear monopoles placed symmetrically with respect to a T-shaped ground plane between them. The antenna has two highly decoupled ports and can provide spatial diversity to combat the multipath interference problem.

Antenna structure, method of using antenna structure and communication device

Abstract: An antenna structure used in a folding portable radio terminal, has a first antenna; and a second antenna, wherein the first antenna is used at least when the portable radio terminal is not folded, and the second antenna is used at least when the portable radio terminal is folded.

Dual-band directional/omnidirectional antenna

Abstract: An antenna having a dual-band driven element and a second antenna element simultaneously produces a directional radiation pattern at an upper frequency and an omnidirectional radiation pattern at a lower frequency. The dual-band driven element is formed as a dipole or monopole with at least one choke connected to the end of the dipole or monopole. In an exemplary embodiment, the dual-band driven element includes a central dipole or monopole that has chokes formed as u-shaped extensions located at the ends of the central antenna dipole or monopole. An antenna array includes the dual-band driven element and a second driven antenna element with a reflector and/or a director in a Yagi-Uda configuration. An antenna array includes the dual-band driven element with a reflector or with a reflector and a director in a Yagi-Uda configuration.

High-strength microwave antenna assemblies and methods of use

Abstract: High-strength microwave antenna assemblies (10) and methods of use are described herein. The microwave antenna has a radiating portion (12) connected by a feedline (14) to a power generating source (28), e.g., a generator. The antenna is a dipole antenna with the distal end of the radiating portion being tapered and terminating at a tip to allow for direct insertion into tissue. The antenna can be used individually or in combination with multiple antennas to create a combined ablation field. When multiple antennas are used, microwave energy can be applied simultaneously to all the antennas or sequentially between the antennas. Furthermore, to facilitate positioning the antennas in or near the tissue to be treated, RF energy may be applied at the tip of the antenna to assist in cutting through the tissue.

A dual-band GPS microstrip antenna

Abstract: Design considerations and experimental results of a dual-band circularly polarized stacked microstrip antenna for GPS operations at 1227 and 1575 MHz are presented. The antenna is achieved by stacking two corner-truncated square microstrip patches. The obtained circular polarization (CP) bandwidths, determined from 3-dB axial ratio, are about 15 MHz (about 1.2%) and 17 MHz (about 1.1%) at 1227 and 1575 MHz, respectively. Good CP radiation patterns and antenna gain have also been observed. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 238–240, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10285

Active array antenna and system for beamforming

Abstract: An active antenna array for use in a beamforming antenna system. The antenna array includes multicarrier power amplifiers coupled to each antenna element wherein the outputs of the multicarrier power amplifiers are linearized. The antenna array communicates with a base station control unit located at the base of the cellular tower in digital baseband. Fiber optic transmission lines couple the antenna arrays with the base station control unit. Multicarrier linear power amplifiers may be coupled to the antenna elements to linearize the outputs of the antenna elements. Alternatively, a predistortion circuit is coupled to the antenna elements to linearize the outputs of the antenna elements when multicarrier power amplifiers are used.

Multi frequency stacked patch antenna with improved frequency band isolation

Abstract: The invention is a stacked patch antenna having a plurality of patch antennas having respective operating frequency bands arranged in a stack, each antenna comprising a radiating conductive patch and a first cable comprising a plurality of coaxial conductors separated from each other by dielectric A first conductor of the first cable carries the feed signal for the uppermost antenna and is conductively coupled to a null point of the radiating conductive patch of the uppermost antenna and passes through apertures at the null points of the other ones of the antennas in the stack Each of the successively lower antennas in the stack is coupled to another one of the plurality of conductors of the cable, which conductors reference the other patches to ground With this arrangement, high isolation is maintained between the frequency operating bands Another antenna can be added between each consecutive pair of antennas discussed above, these antennas being fed by the same feed conductor as the antenna above it by parasitic coupling with the antenna above it

Antenna control system

Abstract: An antenna control system enabling the remote variation of antenna beam tilt. A drive means continuously adjusts phase shifters of a feed distribution network to radiating elements to continuously vary antenna beam tilt. A controller enables the beam tilt of a number of antenna at a site to be remotely varied.

Multi frequency magnetic dipole antenna structures and methods of reusing the volume of an antenna

Abstract: Various resonant modes of a multiresonant antenna structure share at least portions of the structure volume. The basic antenna element has a ground plane and a pair of spaced-apart conductors electrically connected to the ground plane. Additional elements are coupled to the basic element, such as by stacking, nesting or juxtaposition in an array. In this way, individual antenna structures share common elements and volumes, thereby increasing the ratio of relative bandwidth to volume.

An inverted microstrip-fed cavity-backed slot antenna for circular polarization

Abstract: This letter presents a compact circularly polarized cavity-backed four-slot antenna using an inverted configuration. The four-element slot antenna is fed by a microstrip network on the topside of the substrate, while a metallic cavity of rectangular shape is placed in the slot side of the substrate. The measured 10-dB return loss and 3-dB axial ratio bandwidths at the center frequency 6 GHz are 26.6% and 15%, respectively. The measured antenna gain for right-hand circular polarization (RHCP) is 8.7 dBi at 6.0 GHz.

Loop antenna device

Abstract: A loop antenna device has a first antenna generating a first magnetic field and a second antenna generating a second magnetic field such that the first magnetic field and the second magnetic field each have a different axis. A series resonant circuit and a parallel resonant circuit are provided for the first antenna and the second antenna, respectively. The series resonant circuit has at least a second coil, a link coil wound around a ferrite core, and a capacitor in series. The parallel resonant circuit has a first coil and a capacitor. When one of the first and second antennas are disposed in the vicinity of a conductor, an electromagnetic wave absorbing member is disposed between a conductor and one of the first and second antennas.

Compact dual-band PIFA with multi-resonators

Abstract: A newly designed dual-band planar inverted-F antenna with three radiating resonators for use in mobile phone devices is presented. A high frequency structure simulator is used to verify the antenna, which operates at the GSM-900 and DCS-1800 bands. Measurements made in real-life conditions to test how the plastic case and user handing influence the performance of the device demonstrate that the bandwidths are larger than those in similar devices reported in the previous literature.

Multielement planar antenna

Abstract: A multielement planar antenna has a substrate, a plurality of antenna element pairs disposed on a first main surface of said substrate, each of the antenna element pairs including first and second antenna elements each made of a circuit conductor, a metal conductor disposed on a second main surface of the substrate, and a slot line defined in the metal conductor. Each of the antenna element pairs has a microstrip line interconnecting the first and second antenna elements. The slot line crosses the microstrip lines and is electromagnetically coupled to the microstrip lines for feeding the first and second antenna elements. The slot line is fed at its central area by a microstrip line or a coplanar line.

The dielectric wedge antenna

Abstract: A new modification of the TEM-horn antenna has been developed for ground-penetrating radar (GPR) applications. The antenna is based on a dielectric wedge, and thus, was named the dielectric wedge antenna. Tapering of the metal flairs has been used to match the antenna to the ground and to reduce the late-time ringing. The finite-difference time-domain model of the antenna has been created to investigate physical processes within the antenna and to optimize its performance. The dielectric wedge antenna has shown a superior (in comparison with the TEM-horn) performance by radiation in different types of the ground and has been used in a novel antenna configuration within a GPR system, which is dedicated for landmine detection.

Dual mode switched beam antenna

Abstract: Systems and methods for providing antenna beams having reduced grating and side lobes when steered off of the antenna broadside are disclosed. According to the present invention an arrangement of antenna elements (410) suitable for use in generating antenna beams steered at greater angles off of the antenna broadside is utilized with a beam feed network (Figure 5) consistent with the antenna beams being steered at the greater angles and reduced antenna element spacing to provide the reduced grating and side lobes. A preferred embodiment utilizes a 2n+l Butler matrix (510) coupled to 2n+l antenna columns spaced according to the present invention to provide 2n antenna beams. Preferred embodiments provide a dual mode antenna system (Figure 10) in which antenna elements of a first mode are interspersed with antenna elements of a second mode.