Showing papers on "Coaxial antenna published in 2007"

Small Printed Ultrawideband Antenna With Reduced Ground Plane Effect

Abstract: A small printed antenna is described with a reduced ground-plane effect for ultrawideband (UWB) applications. The radiator and ground plane of the antenna are etched onto a piece of printed circuit board (PCB) with an overall size of 25mmtimes25 mmtimes1.5 mm. A notch is cut from the radiator while a strip is asymmetrically attached to the radiator. The simulation and measurement show that the miniaturized antenna achieves a broad operating bandwidth of 2.9-11.6 GHz for a 10-dB return loss. In particular, the ground-plane effect on impedance performance is greatly reduced by cutting the notch from the radiator because the electric currents on the ground plane are significantly suppressed at the lower edge operating frequencies. The antenna features three-dimensional omni-directional radiation with high radiation efficiency of 79%-95% across the UWB bandwidth. In addition, a parametric study of the geometric and electric parameters of the proposed antenna will be able to provide antenna engineers with more design information

A Novel Dual-Band Printed Diversity Antenna for Mobile Terminals

Abstract: A novel dual-band printed diversity antenna is proposed and studied. The antenna, which consists of two back-to- back monopoles with symmetric configuration, is printed on a printed circuit board. The effects of some important parameters of the proposed antenna are deeply studied and the design methodology is given. A prototype of the proposed antenna operating at UMTS (1920-2170 MHz) and 2.4-GHz WLAN (2400-2484 MHz) bands is provided to demonstrate the usability of the methodology in dual-band diversity antenna for mobile terminals. In the above two bands, the isolations of the prototype are larger than 13 dB and 16 dB, respectively. The measured radiation patterns of the two monopoles in general cover complementary space regions. The diversity performance is also evaluated by calculating the envelope correlation coefficient, the mean effective gains of the antenna elements and the diversity gain. It is proved that the proposed antenna can provide spatial and pattern diversity to combat multipath fading.

Circularly Polarized U-Slot Antenna

Abstract: Circularly polarized single-layer U-slot microstrip patch antenna has been proposed. The suggested asymmetrical U-slot can generate the two orthogonal modes for circular polarization without chamfering any corner of the probe-fed square patch microstrip antenna. A parametric study has been carried out to investigate the effects caused by different arm lengths of the U-slot. The thickness of the foam substrate is about 8.5% of the wavelength at the operating frequency. The 3 dB axial ratio bandwidth of the antenna is 4%. Both experimental and theoretical results of the antenna have been presented and discussed. Circular polarization, printed antennas, U-slot.

Dipole tag antenna structure mountable on metallic objects using artificial magnetic conductor for wireless identification and wireless identification system using the dipole tag antenna structure

Abstract: Provided are a dipole tag antenna using an artificial magnetic conductor (AMC) for wireless identification and a wireless identification system using the dipole tag antenna. The dipole tag antenna includes: a substrate formed of a first dielectric material; a conductive ground layer formed underneath the substrate; an AMC layer formed on the substrate; the dipole tag antenna mounted on the AMC layer and comprising a wireless identification chip; and the AMC directly mounted on a conductor.

System and method for re-aligning antennas

Abstract: A system for re-aligning an antenna communicating signals point-to-point. The system may include a first antenna, a second antenna configured to communicate a communications signal with the first antenna using point-to-point communications, and a position controller coupled to the first antenna and configured to re-align the first antenna with respect to the second antenna in response to determining a misalignment of the antenna.

Reconfigurable Square-Ring Patch Antenna With Pattern Diversity

Abstract: A single-feed reconfigurable square-ring patch antenna with pattern diversity is presented. The antenna structure has four shorting walls placed respectively at each edge of the square-ring patch, in which two shorting walls are directly connected to the patch and the others are connected to the patch via pin diodes. By controlling the states of the pin diodes, the antenna can be operated at two different modes: monopolar plat-patch and normal patch modes; moreover, the 10 dB impedance bandwidths of the two modes are overlapped. Consequently, the proposed antenna allows its radiation pattern to be switched electrically between conical and broadside radiations at a fixed frequency. Detailed design considerations of the proposed antenna are described. Experimental and simulated results are also shown and discussed

Simple Broadband Planar CPW-Fed Quasi-Yagi Antenna

Abstract: In this letter, we present a novel coplanar waveguide fed quasi-Yagi antenna with broad bandwidth. The uniqueness of this design is due to its simple feed selection and despite this, its achievable bandwidth. The 10 dB return loss bandwidth of the antenna is 44% covering X-band. The antenna is realized on a high dielectric constant substrate and is compatible with microstrip circuitry and active devices. The gain of the antenna is 7.4 dBi, the front-to-back ratio is 15 dB and the nominal efficiency of the radiator is 95%.

Ultrawideband Band-Notched Folded Strip Monopole Antenna

Abstract: We propose a new band-notched folded strip monopole antenna for ultrawideband applications. This antenna is composed of a forked-shape radiator and a 50 Omega microstrip line. To achieve band-rejected filtering property at the WLAN bands, the forked-shape strips are folded back and result in a pair of coupled lines on the radiator. The length and gap width of the coupled lines primarily determine the notched frequency of the antenna. Based on the band-notched resonance, an equivalent circuit model is proposed for the antenna and the calculated antenna input admittance agrees with the full-wave simulation data. With the help of the dimensionless normalized antenna transfer function, the radiation characteristics are investigated thoroughly. The transmission responses of a transceiving antenna system and their corresponding transient analysis are discussed at the end of this paper.

Methods and systems of changing antenna polarization

Abstract: Methods and systems of changing antenna polarization. At least some of the illustrative embodiments are systems comprising an antenna having a first feed point and a second feed point, an antenna communication circuit, and a switch assembly that selectively couples the antenna communication circuit to the first feed point, and that selectively couples the antenna communication circuit to the second feed point. The feed point (or group of feed points) is selected, for example, based on polarization of an electromagnetic wave to be radiated from or received by the antenna.

Principles of planar near-field antenna measurements

Abstract: This single volume provides a comprehensive introduction and explanation of both the theory and practice of 'Planar Near-Field Antenna Measurement' from its basic postulates and assumptions, to the intricacies of its deployment in complex and demanding measurement scenarios.

A Miniaturized Elliptic-Card UWB Antenna With WLAN Band Rejection for Wireless Communications

Abstract: An elliptic-card ultra-wideband (UWB) (3-11 GHz) planar antenna is designed and miniaturized. It consists of an elliptic radiating element and a rectangular ground plane. A novel feeding mechanism is proposed to feed the antenna by using a microstrip line on the other side of the substrate and connecting the line to the elliptic element by a via. The structure of the antenna is miniaturized by optimizing its elliptic profile and the required ground plane to obtain only 22 times 40 mm dimension. The antenna is then modified to possess band rejection at the wireless local area network (5.1-5.8 GHz) band by adding two slits within the elliptic element. Critical antenna characteristics are verified by measurements including the antenna transfer function. Housing effects on the antenna performance are also studied. The satisfactory overall performance with such a simple structure and small size makes this antenna a viable candidate for UWB wireless communications applications.

Dual Band Proximity-Fed Stacked Patch Antenna for Tri-Band GPS Applications

Abstract: A novel proximity-fed stacked patch antenna is presented to cover the new GPS band, namely L5 (1176 MHz, available after 2007) together with the L1 and L2 bands (1575 and 1227 MHz). High permittivity dielectric material is used to minimize the antenna size down to 1.2''times1.2'', implying an aperture size of only lambda/8timeslambda/8 at the L5 band. Quadrature phase feeding is employed to ensure RHCP radiation, with a broadside gain of 2 dBi. Because of its reduced size, the presented antenna can be used within a GPS antenna array or other tri-band GPS applications. The design procedures and employed tuning techniques to achieve the desired performance are presented

Internal Compact Dual-Band Printed Loop Antenna for Mobile Phone Application

Abstract: A novel dual-band printed loop antenna very promising for application in mobile phones as an internal antenna is presented. The antenna comprises an outer loop strip and an inner inverted-L strip connected to and enclosed by the outer loop strip. The antenna occupies a compact area of 15 times 50 mm2 only, yet generating three resonant modes to form two wide bands at about 900 and 1800 MHz for the Global System for Mobile Communication/Digital Communication System operation. Detailed design considerations of the three excited modes are described in the paper. When a shielding metal case is placed close to the antenna, small effects on the antenna's impedance matching are seen, allowing compact integration of the antenna with nearby conducting elements or electronic components. The antenna is also found to result in small excited surface current distributions on the system ground plane of the mobile phone. This behavior is expected to lead to reduced user's hand effects on the radiation efficiency of the antenna

Dual-Frequency Circularly-Polarized Patch Antenna With Compact Size and Small Frequency Ratio

Abstract: A novel probe-fed single-layer annular-ring patch antenna for dual-frequency circular polarization is evaluated numerically and experimentally verified. The proposed antenna consists of a small circular patch surrounded by two concentric annular-rings, which is loaded by an unequal lateral cross-slot ground plane. The circularly-polarized frequency ratio of the two resonant modes is tunable to a small value, suitable for wireless communications systems. The patch size of the proposed antenna is reduced by about 53% compared to the conventional circular patch at a given frequency. The radiation characteristics of the novel antenna are also presented.

Amplitude-Only Pattern Nulling of Linear Antenna Arrays with the Use of Bees Algorithm

Abstract: An efficient method based on bees algorithm (BA) for the pattern synthesis of linear antenna arrays with the prescribed nulls is presented. Nulling of the pattern is achieved by controlling only the amplitude of each array element. Numerical examples of Chebyshev pattern with the single, multiple and broad nulls imposed at the directions of interference are given to show the accuracy and flexibility of the BA.

Zeroth Order Resonance Loop Antenna

Abstract: A new type of low-profile omnidirectional antenna is proposed in this paper. The proposed antenna has the conceptual configuration of the horizontal magnetic loop current on perfect electric conductor plane, which has been realized by the zeroth-order resonator (ZOR) antenna using mushroom structure. The mushroom structure as a transmission line has negative, zero, and positive propagation constant depending on its operation frequency since mushroom structure is artificial composite right-left handed transmission line. Zeroth-order resonance, of which frequency is independent of physical length, is naturally presented. In particular, mushroom ZOR antenna generates a uniform vertical electric field against ground plane, so that it omnidirectionally radiates in a horizontal plane. Operation frequency, absolute gain, and gain variations for omnidirectional radiation of the designed prototype are 7.9 GHz, 2.6dBi, less than 1.5 dBi, respectively

A Printed Crescent Patch Antenna for Ultrawideband Applications

Abstract: A miniaturized crescent-shape microstrip antenna is proposed for ultrawideband (3-10 GHz) applications. The crescent antenna is evolved from an elliptical patch antenna by carving a circular hole inside symmetrically. The circular aperture introduces an additional antenna in-band resonance and provides wider bandwidth with more design flexibility. The radiation characteristics of this crescent antenna are investigated with full-wave electromagnetic simulations and compared with an elliptical antenna. A crescent antenna prototype that occupies only 60% area of the elliptical patch is fabricated and tested. Antenna pattern and impedance measurements show good performance over the 3-10 GHz band with consistent radiation patterns, low cross polarization, and a substantial gain. The design method is also described

Gain Enhancement of a Microstrip Patch Antenna Using a Cylindrical Electromagnetic Crystal Substrate

Abstract: The performance of a circular microstrip patch antenna is improved using a new cylindrical electromagnetic bandgap (EBG) substrate. The microstrip patch antenna is fed by a coaxial probe and is integrated within a cylindrical electromagnetic bandgap substrate, based on the mushroom-like substrate, to increase the antenna gain. The cylindrical electromagnetic bandgap structure is a combination of two periodic structures with different periods. One is made of metallic rings and the other of grounding vias, which are disposed such as to form a radially and circularly periodic structure. A parametric analysis using a full-wave method was carried out in order to design the EBG structure. With the proposed concept, an antenna prototype was fabricated and tested. The radiation patterns and return loss obtained from measurements show a good impedance matching and a gain enhancement of the proposed antenna.

A Broadband CPW-Fed T-Shape Slot Antenna

Abstract: A novel broadband design of a coplanar waveguide (CPW) fed T-shape slot antenna is proposed and experimentally studied. The size of the proposed antenna is reduced by over 26% compared to the reported wide slot antenna. The obtained results show that the impedance bandwidth, determined by 10-dB return loss, of the proposed slot antenna can be as large as 5690 MHz or about 121% centered at about 4.695 GHz. The design considerations for achieving broadband operation of the proposed slot antenna are described, and experimental results are presented.

Compact Asymmetric Coplanar Strip Fed Monopole Antenna for Multiband Applications

Abstract: A compact asymmetric coplanar strip fed monopole antenna for multiband applications is presented. The antenna exhibits three resonances around 1.8, 2.4, and 5.6 GHz covering the DCS/PCS/UMTS/IEEE 802.11b/g/IEEE802.11a/HIPERLAN2 bands. The multiband characteristic of the antenna is due to the various meandered current paths excited in the radiating structure. The antenna has an overall dimension of only 2830 when printed on a substrate of dielectric constant 4.4. The uniplanar design, simple feeding technique and compactness make it easy for the integration of the antenna into circuit boards. Details of the antenna design, experimental and simulated results are presented and discussed.

A Reconfigurable Quadri-Polarization Diversity Aperture-Coupled Patch Antenna

Abstract: We present a novel reconfigurable quadri-polarization diversity aperture-coupled patch antenna which can provide four polarization states. By controlling the dc bias voltage of the pin-diodes on the feeding network, we can reconfigure the proposed antenna to provide a pair of orthogonal linear polarizations and a pair of orthogonal circular polarizations. Numerical and experimental results validate our design. This novel antenna provides potential polarization diversity features for wireless local area networks and multiple-input multiple-output systems

Cylindrical electronically scanned antenna

Abstract: The antenna (1) has a series of radial wave guides (2) arranged in cylinder for producing antenna beam (8), where the antenna has cylindrical shape. A phase shifter has an input lighted by hyperfrequency sources (4), and an output connected to an input of the radial guides. A pair of phase shifting cells is coupled to wave guide 3 decibel couplers, where an input wave obtained from the sources is phase shifted based on controllable phase shift.

Wideband Circularly Polarized Dielectric Resonator Antenna

Abstract: A circularly polarized quadruple strip feed cylindrical dielectric resonator antenna utilizing a pair of 90deg hybrid couplers is investigated experimentally. The antenna is shown to deliver an impedance bandwidth (S11 < -10 dB) of 34.5%, from 1.75 to 2.48 GHz, and an axial-ratio bandwidth (AR < 3 dB) of 25.9%, from 1.65 to 2.14 GHz. The gain and radiation patterns are found to be stable within the passband.

Heptagonal antenna array system

Abstract: An antenna system includes a heptagonal antenna array having one center antenna element and seven circumferentially surrounding antenna elements offering improved near and far sidelobe rejection, which is well suited for mechanically-gimbaled and time delayed electrical steering antenna applications.

A compact ultra-wideband slot antenna with multiple notch frequency bands

Abstract: A compact printed ultra-wideband slot antenna with superior multiple band-notched characteristics is presented. The size of the UWB slot antenna is minimized, and multiple split ring resonators are printed inside the inner patch to achieve multiple notch frequency bands. As a practical example, a UWB antenna (working from 2.4 to 10.1 GHz) etched with two sets of split ring resonators are fabricated and its VSWR and radiation patterns are measured. The measured results agree well with the simulation, and the two notch frequency bands are centered at 3.65 and 5.75 GHz. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 3056–3060, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22892

Left-Handed Dipole Antennas and Their Implementations

Abstract: A new type of dipole antenna using a left-handed transmission line is proposed. The antenna is composed of a transmission line loaded periodically with shunt inductors and series capacitors. The placement of capacitors into one side only of the line leads to currents of different amplitude on the two sides. Because out-of-phase currents have different amplitudes, they do not completely cancel in the far field, and as a result radiate. Numerical investigation of a wire model shows a unique feature of left-handed transmission lines, which is a reduced wavelength with decreasing frequency. Measured results of two antennas are presented. One is a short dipole antenna working at n=-1, based on conventional resonance numbering. The antenna of 0.18 wavelengths in free space has a gain of -3.9 dBi and bandwidth of 1.7% for |S11 |<-10 dB. The other is a meandered dipole antenna working at n=-9. Polarization orthogonal to a right-handed one is achieved by the induced current of |-9| half wavelengths on the meander having 0.77 wavelengths in free space

Wideband microstrip patch antenna design for breast cancer tumour detection

Abstract: A patch antenna is presented which has been designed to radiate frequencies in the range 4-9.5 GHz into human breast tissue. The antenna is shown by means of previously unpublished simulation and practical measurements to possess a wide input bandwidth, radiation patterns that remain largely consistent over the band of interest and a good front-to-back ratio. Consideration is also given to the antenna's ability to radiate a pulse, and in this respect it is also found to be suitable for the proposed application

Ultrawide-band printed monopole antenna with band-notch filter

Abstract: A simple and compact microstrip-fed ultrawide-band (UWB) printed monopole antenna with band-notch filter is proposed. The antenna is composed of two monopoles of the same size and a small strip bar which leads to the desired high attenuation at the notch frequency. The band-notch mechanism and current distribution of the antenna are examined. Finally, the frequency-domain characteristics, such as system transfer function and group delay, of the proposed identical monopole antenna pair are analysed to evaluate the antenna performance for UWB applications.

Antenna device and wireless communication apparatus

Abstract: An antenna device includes a feeding coil antenna and a booster coil antenna electromagnetically coupled to the feeding coil antenna. The feeding coil antenna includes a plurality of coil portions including at least one magnetic body and each including a coil conductor wound around the at least one magnetic body. The plurality of coil portions are connected to one another in an in-phase mode, and are arranged near one another such that winding axes of the coil conductors are oriented approximately in the same direction and at least portions of respective openings of the coil conductors face one another.

Optimal design of dualband cpw-fed g-shaped monopole antenna for wlan application

Abstract: A dualband coplanar waveguide (CPW)-fed planar monopole antenna suitable for WLAN application is presented in this paper. The antenna resembling as a "G" shape and optimally designed by using the particle swarm optimization (PSO) algorithm can produce dual resonant modes and a much wider impedance bandwidth for the higher band. Prototypes of the obtained optimized antenna have been constructed and tested. The measured results explore good dualband operation with −10 dB impedance bandwidths of 9.7% and 62.8% at bands of 2.43 and 4.3 GHz, respectively, which cover the 2.4/5.2/5.8 GHz WLAN operating bands, and show good agreement with the numerical prediction. Also, good antenna performances such as radiation patterns and antenna gains over the operating bands have been observed.