Showing papers in "IEEE Antennas and Wireless Propagation Letters in 2004"
TL;DR: In this article, a dual-printed inverted-F antenna diversity system for terminal devices operating at 5.2 GHz under both switched and combining schemes is presented, where diversity performance is evaluated by means of the calculated envelope correlation coefficient, the mean effective gain and the effective diversity gain of the two antennas.
Abstract: Dual-printed inverted-F antenna diversity systems for terminal devices operating at 5.2 GHz under both switched and combining schemes are presented. Diversity performance is evaluated by means of the calculated envelope correlation coefficient, the mean effective gain and the effective diversity gain of the two antennas. An investigation into the effect of the antennas' placement and of the corrugated ground plane on the performance of the system has also been conducted. It is shown that many configurations can provide uncorrelated signals of the same power level, but with significantly different radiation pattern complementarity, antenna efficiency, and effective diversity gain.
256 citations
TL;DR: In this paper, the authors show that the proper use of time modulation in equispaced linear arrays with uniform excitation distribution is possible to maintain the sidelobe zone of the radiated power below a certain - previously stipulated - level, whereas the undesired harmonics are minimized.
Abstract: The letter shows that, by the proper use of time modulation in equispaced linear arrays with uniform excitation distribution, it is possible to maintain the sidelobe zone of the radiated power below a certain - previously stipulated - level, whereas the undesired harmonics are minimized. In addition to that, the further extension of the technique to non-equispaced arrays permits a broadband response to be obtained, by simply searching the positions of the elements that reach the desired power pattern behavior within the required bandwidth.
246 citations
TL;DR: In this article, an experimental investigation was conducted on printed wide-slot antennas fed by microstrip lines for wideband applications, and two designs with significantly enhanced impedance bandwidths and improved radiation patterns were obtained.
Abstract: An experimental investigation was conducted on printed wide-slot antennas fed by microstrip lines for wideband applications. Results show that the impedance matching of this kind of antenna is greatly affected by the feed-slot combination and feed gap width, with the slot shape being a main contributor of the radiation characteristics. By properly choosing suitable slot shapes, selecting similar feed shapes and tuning their dimensions, two designs with significantly enhanced impedance bandwidths and improved radiation patterns are obtained.
238 citations
TL;DR: In this paper, an ultrawide-band coplanar waveguide (CPW) fed slot antenna is presented, which is excited by a 50/spl Omega/CPW with a U-shaped tuning stub.
Abstract: An ultrawide-band coplanar waveguide (CPW) fed slot antenna is presented. A rectangular slot antenna is excited by a 50-/spl Omega/ CPW with a U-shaped tuning stub. The impedance bandwidth, from both measurement and simulation, is about 110% (S11<-10 dB). The antenna radiates bi-directionally. The radiation patterns obtained from simulations are found to be stable across the matching band and experimental verification is provided at the high end of the band.
221 citations
TL;DR: This letter proposes a double-sided printed bow-tie antenna for ultra wide band (UWB) applications that has a return loss less than 10 dB, phase linearity, and gain flatness over the above frequency band.
Abstract: This letter proposes a double-sided printed bow-tie antenna for ultra wide band (UWB) applications. The frequency band considered is 3.1-10.6 GHz, which has been approved by the Federal Communications Commission as a commercial UWB band. The proposed antenna has a return loss less than 10 dB, phase linearity, and gain flatness over the above frequency band.
206 citations
TL;DR: In this paper, the authors presented the implementation of electromagnetic band-gap (EBG) structures with an inherently wide-band Archimedean spiral antenna, which is designed to emulate a perfect magnetic conductor.
Abstract: This letter presents the implementation of electromagnetic band-gap (EBG) structures with an inherently wide-band Archimedean spiral antenna The EBG structure is designed to emulate a perfect magnetic conductor The combination of technologies produces a low-profile and wide-band antenna Utilization of an EBG structure offers an antenna height reduction of more than 69%, including the thickness of the EBG structure, compared to the traditional /spl lambda//4 cavity backed implementation of spiral antennas Specifically, this approach allows the spiral antenna to maintain a considerable fraction (71 %) of its designed inherent broad-band behavior with no loss to its directive gain In addition, the presented design offers full scalability
184 citations
TL;DR: In this article, a rectenna designed with a microstrip harmonic-rejecting circular sector antenna at 2.4 GHz was proposed, which exhibits high reflection coefficients at the second and the third harmonics, generated by a diode.
Abstract: A rectenna designed with a microstrip harmonic-rejecting circular sector antenna at 2.4 GHz is proposed. As compared to a conventional microstrip square-patch antenna, the circular sector antenna, using inset feeding, exhibits high reflection coefficients at the second and the third harmonics, generated by a diode. The rectenna with integrated circular sector antenna can eliminate the need for a lowpass filter (LPF) placed between the antenna and the diode as well as producing higher output power, with a maximum conversion efficiency of 77.8% using a 150-/spl Omega/ load resistor.
150 citations
TL;DR: In this paper, the aperture's electric field distribution is manipulated to create two fictitious short circuits along the slot, hence creating two additional resonances besides the main one, and the frequencies of these fictitious resonances can be chosen such that the overall bandwidth of the antenna is drastically increased.
Abstract: A technique for designing wideband slot antennas is proposed. By selecting the topology of the microstrip feed network, the aperture's electric field distribution is manipulated to create two fictitious short circuits along the slot, hence creating two additional resonances besides the main one. The frequencies of these fictitious resonances can be chosen such that the overall bandwidth of the antenna is drastically increased. By using this technique, a slot antenna with a 1.8:1 bandwidth ratio is designed and fabricated. The measured results of this antenna show similar radiation patterns at different frequencies in its band of operation. Furthermore, the antenna has a relatively constant gain and, more importantly, it has an excellent polarization purity over the entire bandwidth.
142 citations
TL;DR: Fixed wireless access channels in the 5 GHz band have been measured with eight-element uniform linear antenna arrays at both ends, thus providing an 8/spl times/8 configuration.
Abstract: Fixed wireless access channels in the 5 GHz band have been measured with eight-element uniform linear antenna arrays at both ends, thus providing an 8/spl times/8 configuration. The measurements were performed at three different locations in downtown Toronto. The application of the time reversal (TR) technique in a multiple-input-single-output (MISO) configuration can reduce the delay spread of the channel impulse response by a factor of 2-3, depending on the power allocation scheme.
132 citations
TL;DR: In this paper, a polynomial-rooting-based algorithm for multiple-source azimuth-elevation direction-finding and polarization estimation using dipoles, loops, and/or circularly polarized antennas is presented.
Abstract: This letter advances a new polynomial-rooting-based algorithm for multiple-source azimuth-elevation direction-finding and polarization estimation, using dipoles, loops, and/or circularly polarized antennas, which may arbitrarily collocate or orient on an L-shaped uniformly spaced array grid. The number, orientations or types of these antennas may vary from array grid point to array grid point.
128 citations
TL;DR: In this paper, a new definition of mutual impedance for two dipole antennas is introduced to characterize the mutual coupling effect between two Dipole antennas in a more accurate manner, and the calculation method and the measurement procedure for the new mutual impedance are given.
Abstract: A new definition of mutual impedance for two dipole antennas is introduced to characterize the mutual coupling effect between two dipole antennas in a more accurate manner. The calculation method and the measurement procedure for the new mutual impedance are given. Measurement and theoretical results on two monopole antennas were obtained as an example. The new mutual impedance was successfully applied in the compensation of the mutual coupling effect in direction finding and adaptive interference suppression with significantly improved results, showing the importance of the new mutual impedance.
TL;DR: In this article, an innovative low profile, lightweight dual band (L1+L2) GPS radiator with a high multipath-rejection capability is presented, which is realized by two stacked shorted annular elliptical patch antennas.
Abstract: Since the Global Positioning System (GPS) was launched, significant progress has been made in GPS receiver technology but the multipath error remains an unsolved problem. As solutions based on signal processing are not adequate, the most effective approach to discriminate between direct and multipath waves is to specify new and more restrictive criteria in the design of the receiving antenna. An innovative low profile, lightweight dual band (L1+L2) GPS radiator with a high multipath-rejection capability is presented. The proposed solution has been realized by two stacked shorted annular elliptical patch antennas. In what follows, a detailed account of the design process and antenna performances is given, presenting both simulated and experimental results.
TL;DR: In this article, a compact six-band internal handset antenna for covering the GSM (890-960 MHz), GPS (1575 MHz), DCS (1710-1880 MHz), PCS (1880-1990 MHz), UMTS (1900-2200 MHz), and ISM (2400-2480 MHz) bands is presented.
Abstract: A novel compact six-band internal handset antenna for covering the GSM (890-960 MHz), GPS (1575 MHz), DCS (1710-1880 MHz), PCS (1880-1990 MHz), UMTS (1900-2200 MHz), and ISM (2400-2480 MHz) bands is presented. The proposed antenna consists of two layer patches and a folded stub and occupies a total volume of 36/spl times/17/spl times/8 mm/sup 3/. Details of the antenna as well as the measured results are presented.
TL;DR: In this paper, the concept of connected (or coupled) dipoles in a linear array, which improves wideband performance, is examined, and a long wire with multiple feeds is the model, using rigorous moment method analysis.
Abstract: The concept of connected (or coupled) dipoles in a linear array, which improves wideband performance, is examined. A long wire with multiple feeds is the model, using rigorous moment method analysis. The edge waves of the current appear not to be attenuated; around half-wave dipole length, the current peaks are one wavelength apart, with deep nulls. For dipole lengths around quarter-wave the current peaks and dips are modest. This trend continues to shorter dipoles; for lengths of 0.1 wavelength or less, the current is nearly constant along the array. This approximates the current sheet of Wheeler; the impedance mismatch is much less severe than for an array of unconnected dipoles of the same dimensions.
TL;DR: In this paper, a hybrid structure consisting of a DRA, a circular slot and an eccentric ring slot on a co-plane ground plane is proposed to achieve dual-frequency operation.
Abstract: To achieve dual-frequency operation, a new design concept that utilizes a hybrid structure that includes a dielectric resonator antenna (DRA) and a slot radiating resonator was investigated experimentally. The proposed structure consists of a DRA, a circular slot and an eccentric ring slot on a co-plane ground plane. This arrangement can be described as two cascaded resonant circuits that resonate at two different frequencies. One is from the DRA and the other from the ring slot. Based on the proposed design concept, a number of phototypes have been successfully designed, fabricated and tested. The measured results have demonstrated the validity of the proposed design.
TL;DR: A new approach of using text as a meander line for size reduction of dipole antennas used in passive transponders for radio frequency identification (RFID) systems is proposed.
Abstract: A new approach of using text as a meander line for size reduction of dipole antennas used in passive transponders for radio frequency identification (RFID) systems is proposed Three different structures of text dipole antennas for 869 MHz RFID applications have been examined numerically using a finite element method simulator The impedance matching and the radiation properties of the fabricated antennas are measured and the results are compared with the simulated values
TL;DR: In this article, a new annular ring microstrip patch resonator with reduced size is proposed, where the underlying material is partially occupied by a ring of metamaterial with negative permittivity and permeability.
Abstract: A new annular ring microstrip patch resonator with reduced size is proposed. The underlying material is partially occupied by a ring of metamaterial with negative permittivity and permeability. It is shown that the resonant frequency of the TM/sub 110/ cavity mode can be made as small as we desire by proper choice of dimensions and material parameters. Relevance to the design of compact patch antennas for wireless receivers is indicated.
TL;DR: In this paper, a metamaterial surface is formed by a thin dielectric slab on both sides of which "gangbuster" dipoles are printed inside a 1D cavity resonator, which has the effect of decreasing the resonant frequency.
Abstract: We suggest an idea for miniaturization of cavities by utilizing a properly designed metamaterial thin surface inserted inside the cavities. This metamaterial surface is constituted by a thin dielectric slab on both sides of which "gangbuster" dipoles are printed. Inserting the thin slab inside a parallel-plate one-dimensional (1D) cavity resonator has the effect of decreasing the resonant frequency. Placing the metamaterial slab at the center of a rectangular waveguide lowers the cut-off frequency of the dominant mode of the waveguide also. The corresponding dispersion curve exhibits a smooth transition from a fast-wave to a slow-wave regime and then asymptotically tends to the dispersion curve of the first TE surface-wave mode of the metamaterial slab. This suggests a natural way to conceive a 3D compact cavity resonator by placing two perfectly electrically conducting walls, a half of the wavelength of the slow-wave mode apart, inside the above rectangular waveguide. The analysis, performed by a circuit network theory and validated by a full-wave numerical analysis, provides simple formulas to predict the resonant frequency and the dispersion diagrams of these structures.
TL;DR: In this paper, a cylindrical antenna that operates at 2.4 GHz is simulated and presented, where the E-plane directivity of a simple radiating dipole positioned in front of a metallic cylinder is improved.
Abstract: This work presents a new method to realize directive base station antennas by incorporating cylindrical electromagnetic bandgap (EBG) structures. The EBG structure behaves as a partially reflecting surface (PRS) and significantly enhances the E-plane directivity of a simple radiating dipole positioned in front of a metallic cylinder. A novel cylindrical antenna that operates at 2.4 GHz is simulated and presented.
TL;DR: A novel microstrip patch antenna with a Koch prefractal edge and a U-shaped slot is proposed for multi-standard use in GSM1800, UMTS, and HiperLAN2 and an interesting size reduction is achieved.
Abstract: A novel microstrip patch antenna with a Koch prefractal edge and a U-shaped slot is proposed for multi-standard use in GSM1800, UMTS, and HiperLAN2. Making use of an inverted-F antenna (PIFA) structure, an interesting size reduction is achieved. The multi-band behavior has been obtained by broadening the lower frequency resonance of the fractal patch to cover GSM1800 and UMTS, and inserting a U-slot dimensioned for the HiperLAN2 band. The effect of the small ground plane has been taken into account. Experimental results have validated the design procedure and confirm the fulfillment of the requirements for multistandard mobile terminal applications.
TL;DR: In this paper, a patch antenna is proposed for wideband and low cross-polarization operation by introducing a meandering strip feeding structure, which is suitable for both planar and curved grounding structures, where the impedance bandwidths of 24% and 32% can be obtained, respectively.
Abstract: A patch antenna is proposed for wideband and low cross-polarization operation by introducing a meandering strip feeding structure. The investigation shows that this feeding technique is suitable for both planar and curved grounding structures, where the impedance bandwidths (SWR < 2) of 24% and 32% can be obtained, respectively. In both cases, the cross-polarization levels are less than -20 dB in E- and H-planes across the passband. Also, symmetrical and stable radiation patterns are obtained. Simulation results are compared with experiments and good agreement is observed.
TL;DR: In this article, the perfectly matched layer (PML) absorbing boundary condition is shown to be analytically unstable for a material with a bandwidth of negative refractive index (NIM).
Abstract: The perfectly matched layer (PML) absorbing boundary condition is shown to be analytically unstable for a material with a bandwidth of negative refractive index. Physically, this is a consequence of the reversed phase and group velocities in such a medium. The instability is inherent in the PML and is not implementation-specific. We derive a modified PML (NIMPML) that is analytically stable in a negative index material (NIM), and we demonstrate its numerical stability in a specific NIMPML implementation.
TL;DR: In this article, a high-impedance surface is chosen as EBG structure, and the numerical simulation is performed by periodic Green's functions plus the moment method, both the bandgap curve of the EBG and the scan characteristics of the phased arrays have been calculated.
Abstract: Electromagnetic bandgap (EBG) material is applied in the design of a phased array of rectangular microstrip patches. The surface-waves could be suppressed by the frequency bandgap and, therefore, the scan blindness could be eliminated. A high-impedance surface is chosen as EBG structure, and the numerical simulation is performed by periodic Green's functions plus the moment method. Both the bandgap curve of the EBG structure and the scan characteristics of the phased arrays have been calculated. The elimination of scan blindness is observed.
TL;DR: In this article, a very low-cost antenna is presented for 802.11b (2.4-2.484 GHz) wireless local area network (WLAN) applications, which can be used in two different configurations.
Abstract: A very low-cost antenna is presented for 802.11b (2.4-2.484 GHz) wireless local area network (WLAN) applications. This antenna can be used in two different configurations. In a stand-alone configuration, the antenna has a 12-dBi gain and a 40/spl deg/ half power beamwidth (HPBW) in both E and H planes, thus matching typical requirements for WLAN base stations or access points for indoor WLAN. Furthermore, the same antenna can be used as feeder for a standard TVSAT offset parabolic reflector, thus obtaining a high-gain antenna system configuration (gain = 23 dBi, HPBW = 12/spl deg/ with an 80 cm reflector), useful for point-to-point connections. The latter configuration provides a very low-cost antenna system useful for an Internet service provider to cover the "last mile" toward the customer via a wireless link. An FR4 epoxy-glass substrate is employed providing a solution that is cheap both in material and manufacturing costs. A "suspended" structure allows the synthesis of an effective material with low dielectric constant and losses, suitable for antennas application, despite the use of FR4; indeed an 86% loss efficiency is obtained. Some prototypes were realized and measured; their input impedance and gain were found to be in satisfactory agreement with the numerical predictions provided by the design tools.
TL;DR: In this paper, simple models for the number of independent samples with mechanical stirring and frequency stirring are presented, and also with several stirring techniques combined, and the models are verified through measurements.
Abstract: The accuracy in reverberation chamber measurements relies on the chamber setup being able to generate a large number of independent measurement samples. Simple models for the number of independent samples with mechanical stirring and frequency stirring are presented, and also with several stirring techniques combined. The models are verified through measurements.
TL;DR: In this paper, a multiple-arm, folded element design is presented that allows a dipole to exhibit a matched impedance and high radiation efficiency when it is very closely spaced to a perfect electric conductor (PEC) ground plane.
Abstract: A multiple-arm, folded element design is presented that allows a dipole to exhibit a matched impedance and high radiation efficiency when it is very closely spaced (<0.05/spl lambda/) to a perfect electric conductor (PEC) ground plane. Impedance matching and a balanced feed are implemented within the antenna structure so that an external matching network and balun are not required. A dipole element design that exhibits self-resonance, a 46 ohm feed point resistance and a radiation efficiency in excess of 90% is described for a spacing of 0.023/spl lambda/ above a PEC ground plane.
Journal Article•
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TL;DR: In this paper, the radiation characteristics of the matched Peano antenna were investigated, which is a single antenna made of a thin wire, patterned after a special type of space-filling curve known as the Peano curve.
Abstract: We investigate the radiation characteristics of the Peano antenna, i.e., a single antenna made of a thin wire, patterned after a special type of space-filling curve known as the Peano curve. We use a moment-method-based simulation code to study various properties of this antenna, namely, the radiation pattern, impedance bandwidth, current distribution, cross-polarization level, radiation efficiency, and the feed location for achieving an electrically small matched antenna. As in the case of the Hilbert antenna, the radiation patterns of a Peano antenna resemble those of a linear dipole; however, this antenna has a lower cross-polarization level than the Hilbert antenna and, for a matched Peano antenna, the resonant frequency is lower than the same order matched Hilbert antenna at the expense of a smaller input-impedance bandwidth.
TL;DR: In this paper, a corrugated conducting plate was used for enhanced microwave transmission and beaming through a subwavelength slot, where the perfect conductor model was employed to describe the metal.
Abstract: Enhanced microwave transmission and beaming through a subwavelength slot placed into a corrugated conducting plate is experimentally observed compared with the case of the single isolated slot. This phenomenon is similar to that happening for optical wavelengths where the surface plasmons model is employed to describe the metal. This letter shows that the phenomenon is also present in the microwave range where the perfect conductor model applies. Enhanced subwavelength transmission and beaming stimulates new research for future applications.
TL;DR: In this article, the lower bound on Q for a lossy straight-wire electric dipole antenna with a straight wire and a circular wire loop was investigated. And the lower bounds on Q were derived directly in terms of the antenna's electrical size and loss resistance and compared with numerical simulations.
Abstract: In this letter, the lower bound on Q is considered for a lossy electric and magnetic dipole antenna formed by a straight wire and a circular wire loop, respectively. Simple expressions for the lower bound on Q are written directly in terms of the dipole antenna's electrical size and loss resistance and are compared with numerical simulations. It is shown that the lower bound on Q for the lossy straight-wire electric dipole increases without bound with decreasing frequency, whereas the lower bound on Q for the lossy circular-loop magnetic dipole approaches zero with decreasing frequency.
TL;DR: The effect of MC on the capacity of multiple-input-multiple-output wireless channels is investigated numerically, which shows the decorrelation resulting from MC is a tradeoff between the mean direction of arrival and the pattern diversity due to MC.
Abstract: Analytical expressions for both the mean received power of each antenna and the spatial correlation (SC) between antennas, in the presence of antenna mutual coupling (MC), are provided. The effect of MC on the mean power imbalance and SC between a pair of mutually coupled antennas is explicitly derived, and the conditions under which MC has no effect on the SC an also identified. The effect of MC on the capacity of multiple-input-multiple-output wireless channels is investigated numerically, which shows the decorrelation resulting from MC is a tradeoff between the mean direction of arrival and the pattern diversity due to MC.