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Antenna Technology: Small Antennas and Novel Metamaterials, 2005. IWAT 2005. IEEE International Workshop on

Date 7-9 March 2005

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Displaying Results 1 - 25 of 174
  • Forward and backward waves in chiral metamaterials

    Publication Year: 2005 , Page(s): 407 - 409
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (93 KB) |  | HTML iconHTML  

    In this presentation, we study basic electromagnetic properties of chiral metamaterials, which can have simultaneously negative permittivity and permeability. The reflectivity of a slab filled with a chiral metamaterial, with possibly negative or constitutive parameters, is analysed and numerical results presented. We consider a monochromatic plane wave propagating in a homogeneous, isotropic medium which illuminates an infinite slab of chiral material. Phenomenon such as electromagnetic propagation in chiral nihility are also discussed. View full abstract»

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  • Nonlinear transmission properties of left-handed metamaterial slab

    Publication Year: 2005 , Page(s): 410 - 413
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (199 KB)  

    We analyze the nonlinear properties of microstructured materials which have a negative refractive index, the so-called left-handed metamaterials. We demonstrate that the hysteresis-type dependence of the magnetic permeability on the field intensity allows changing the material properties from left- to right-handed and back again. Using finite-difference time-domain simulations, we study the wave reflection from a slab of nonlinear left-handed material, and observe the propagation of temporal solitons in such materials. View full abstract»

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  • Study of human head effects on UWB antenna

    Publication Year: 2005 , Page(s): 310 - 313
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (130 KB) |  | HTML iconHTML  

    This paper studies the effects of the human head on an ultra wideband (UWB) antenna on a PCB. To investigate the effects, a numerical model of average dielectric constant and conductivity over the UWB range is used to approximate the human head. The performance of the UWB antenna is compared in free space and on the human head in terms of the impedance match, gain, and radiation patterns. The study has shown that the presence of the head has significant effects on the impedance and radiation performance of the UWB antenna. View full abstract»

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  • The adaptive algorithms of the smart antenna system in future mobile telecommunication systems

    Publication Year: 2005 , Page(s): 347 - 350
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (194 KB) |  | HTML iconHTML  

    The smart antenna (SA) can adjust the direction pattern adaptively and reduce the interference signals using some adaptive interference ing algorithms, and thus enhances the performance of mobile telecommunication systems. It especially enlarges the user system capacity. The smart antenna system is mainly applied to the base station (BS) now, but in the next step, the smart antenna technology will be applied to mobile stations (MS), along with hardware and software in the MS becoming more powerful. This article provides a description and analysis of some basic adaptive algorithms and their modifications. The smart antenna system will be applied in both BS and MS in next generation mobile telecommunication systems. View full abstract»

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  • Design, fabrication and measurement of a photonic crystal substrate patch antenna

    Publication Year: 2005 , Page(s): 314 - 317
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (188 KB) |  | HTML iconHTML  

    Planar microstrip patch antennas can achieve a wide range of radiation patterns. However, due to surface-wave losses, they have low bandwidth, low gain, and a potential decrease in radiation efficiency. In order to minimize the surface-wave effects, a photonic-band gap (PBG) substrate is proposed. The PBG structure significantly diminishes the surface wave modes and thus improves the gain and far-field radiation propagation pattern and efficiency. In this paper, using FDTD, an accurate full wave analysis surface wave propagation in a rectangular microstrip patch antenna with and without PBG is presented. Finally the antenna fabricated and result of measurement was compared with numerical simulation. View full abstract»

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  • Left-handed properties of disordered metamaterials

    Publication Year: 2005 , Page(s): 75 - 78
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (192 KB) |  | HTML iconHTML  

    We present the study of the effect of disorder on the effective magnetic response of composite left-handed metamaterials and their specific properties such as negative refraction. We show that relatively weak disorder in the split-ring resonators can reduce and even completely eliminate the frequency domain where the composite material demonstrates the left-handed properties. We introduce the concept of the order parameter to describe the novel physics of this effect. View full abstract»

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  • Integrated planar log-spiral antenna at terahertz waves

    Publication Year: 2005 , Page(s): 197 - 200
    Cited by:  Papers (4)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (200 KB) |  | HTML iconHTML  

    We present terahertz performance of integrated lens antennas consisting of a complementary log-periodic planar feed and a synthesized elliptical lens. The radiation pattern and the impedance of the planar feed are computed using the method of moments; the action of the lens is evaluated using the physical-optics approach based on the Huygens principle. In the frequency range from 0.6 to 5 THz measured antenna efficiency and radiation pattern correspond fairly well with the results of simulations approving this simulation technique as a reliable tool for the antenna design. View full abstract»

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  • Ultra wideband TEM horn design using multi-objective evolutionary algorithm

    Publication Year: 2005 , Page(s): 339 - 342
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (133 KB) |  | HTML iconHTML  

    The paper proposes a new method for the design of UWB antennas using a multi-objective evolutionary algorithm. The challenges in designing a UWB antenna lie in the critical requirement of the antenna design that it is consistent and predictable across the entire UWB frequency range and in some fundamental limitations (Hansen, R.C., 1981), such as the antenna's size, efficiency and bandwidth. In order to find a tradeoff to balance these conflicting design objectives, a multi-objective evolutionary algorithm is a good solution. A promising UWB antenna - a TEM horn - is chosen for initial study. The effective multi-objective algorithm - strength Pareto evolutionary algorithm (SPEA) (Zizler, E. and Thiele, L., IEEE Trans. Evolutionary Computation, vol.3. no.4, 1999) - is applied to optimize the performance of the antenna over the UWB frequency range. View full abstract»

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  • A novel multi arc slot antenna for WLAN applications

    Publication Year: 2005 , Page(s): 209 - 212
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (135 KB) |  | HTML iconHTML  

    A novel multi arc slot microstrip patch antenna loaded with a shorting post is presented. By embedding four pairs of arc shape slots, dual-band operation centered at 2.441 GHz and 5.2 GHz has been obtained. The proposed antenna is of high gain 6.8 dBi (2.441 GHz) and 5.8 dBi (5.2 GHz), and its impedance bandwidth defined at VSWR<=2 can meet the requirement of WLAN. View full abstract»

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  • Antennas for on-body communication systems

    Publication Year: 2005 , Page(s): 17 - 20
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (187 KB) |  | HTML iconHTML  

    The optimum choice of antenna for on-body communications is discussed in this paper. Several different antennas, including the monopole, the loop and patch and patch arrays have been fabricated and tested in the on-body environment. In particular, path gain measurements of two on-body paths has been performed for a range of body postures. It is clear that the monopole antenna performs best in most of the measurement cases. A first order analysis of the path loss, consisting of antenna gain deduced from link geometry and a free space loss appropriate to the path distance, give results that are within 10 dB of measurements for most body postures. View full abstract»

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  • Small UWB antenna with improved efficiency for pulse radiation

    Publication Year: 2005 , Page(s): 295 - 298
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (219 KB) |  | HTML iconHTML  

    The paper describes an ultra-wideband (UWB) antenna developed for impulse ground penetrating radar (GPR) applications. The antenna is a modified bow-tie antenna designed for short-range GPR applications such as road inspection and non-destructive testing of concrete. For these applications, the transmitted pulses should have minimal ringing to avoid masking of targets. This can be achieved by the application of resistive loading at the expense of radiation efficiency. We have attempted to improve a conventional bow-tie antenna usually used in GPR by reducing the antenna size and minimizing ringing, while at the same time improving the antenna radiation efficiency. View full abstract»

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  • ADBF in the presence of fixed interference perturbation [adaptive array signal processing]

    Publication Year: 2005 , Page(s): 470 - 473
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (143 KB) |  | HTML iconHTML  

    The conventional ADBF algorithm can only form a narrow notch and its performance is quite good when the prior knowledge of interference is accurate. However, when the knowledge of interfering signals is imprecise, which is often the case in practice due to the differences between the assumed signal arrival angle and the actual signal arrival angle, the interference may be moved out of the notch when the position of interference perturbations and the interference cannot be cancelled completely. The SNW approach, proposed in this paper, can generate a fixed wide notch while it can adaptively reject the other interferences. The weights forming the fixed wide notch can be calculated offline according to the actual environment so it does not add extra burden to the entire computation. Its performance is much better than that of MVDR in the present of array errors and interference perturbations. View full abstract»

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  • Experimental and simulated studies of planar inverted-F antenna

    Publication Year: 2005 , Page(s): 299 - 302
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (150 KB) |  | HTML iconHTML  

    This paper proposes a planar inverted-F antenna, where an edge of the radiator is terminated with a shorted plate, and fed by a coaxial probe along the centerline of the radiator. This work includes parametric studies of PIFA behavior, involving the shorting plate width, antenna height, and input impedance on the radiator. The effects of design parameters of the PIFA on its operational frequency, impedance bandwidth and radiation patterns are presented and discussed. View full abstract»

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  • A two-stage detection algorithm for the V-BLAST system

    Publication Year: 2005 , Page(s): 282 - 286
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (188 KB) |  | HTML iconHTML  

    A MIMO system (multiple antennas at the transmitter and receiver) is capable of very high theoretical capacities. Foschini et al. proposed V-BLAST (Vertical-Bell Lab Layered Space-Time) code with a detection algorithm based on linear combination ing and successive symbol cancellation. However this conventional detection algorithm requires time to execute both these computational bottlenecks. The time delay will be enhanced if the number of transmit antennas increases. In order to avoid this obstacle, parallel symbol cancellation (PSC) was proposed. But the performance is degraded. In this paper, we propose a two-stage detection algorithm derived from the combination of SSC and PSC to improve the BER performance. The proposed scheme is applied to zero-forcing (ZF) and minimum mean square error (MMSE) criteria. We also perform simulation to verify the analysis. View full abstract»

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  • Pre-processing blind multiuser detection algorithm in antenna array system and its robustness to DOA estimation error

    Publication Year: 2005 , Page(s): 534 - 538
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (161 KB) |  | HTML iconHTML  

    A pre-processing least squares constant modulus blind multiuser detection algorithm, based on decision-feedback (PDF-LSCMA), in an antenna array system is proposed in this paper. The robustness of PDF-LSCMA to the DOA estimation error and the maximum value of DOA estimation error are also analyzed in this paper. Simulation validates the algorithm and theoretical analysis. View full abstract»

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  • Implementation of the Z matrix interpolation in the method of moments for analysis of transient antennas excited by UWB pulses

    Publication Year: 2005 , Page(s): 258 - 261
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (165 KB) |  | HTML iconHTML  

    In this paper, we implement the Z matrix interpolation technique for ultra-wideband (UWB) transient analysis of antennas excited by short pulses. This kind of analysis usually requires a much larger frequency range in comparison with analysis of wideband time-harmonic antennas. Due to stronger variation of currents at low frequencies down to DC, generally more frequency points are needed in the frequency range. In this work, we attempt to find a general rule of thumb for determining the optimal selection of frequencies for analysis of antennas excited by UWB pulses, using MoM with the Z matrix interpolation technique. View full abstract»

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  • Analysis of a parallel-plate slit array antenna containing magnetoplasma

    Publication Year: 2005 , Page(s): 25 - 28
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (125 KB) |  | HTML iconHTML  

    A problem of radiation from a parallel-plate slit array antenna containing magnetoplasma is solved. The technique of Fourier transform and mode matching is used to obtain a solution. The solution is represented in fast convergent series of discrete modal coefficients. Computation is performed to illustrate the effect of magnetoplasma on antenna radiation. The proposed antenna containing magnetoplasma shows the beam-steering characteristics. View full abstract»

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  • Reconfigurable Hilbert curve patch antenna

    Publication Year: 2005 , Page(s): 521 - 524
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (124 KB) |  | HTML iconHTML  

    A novel reconfigurable Hilbert curve patch antenna (RHCPA) is proposed. The patch is figured using the third order Hilbert curve. By introducing some slots, at least two configurations of the antenna with different radiation patterns are formed. Micro-electro-mechanical systems (MEMS) switches are used to change the antenna configuration and hence the radiation pattern. Simulation results are given. View full abstract»

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  • Miniature embedded multi-band antennas for portable devices

    Publication Year: 2005 , Page(s): 213 - 216
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (209 KB) |  | HTML iconHTML  

    In this paper, we mainly review our recent research progress on developing miniaturized embedded multi-band antennas for portable devices. First a simple measurement setup for measuring small antennas is presented. Then, several new multi-band antennas are demonstrated numerically and experimentally. View full abstract»

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  • A 2D space-frequency receiver with reduced-rank multistage Wiener filters for MC-CDMA systems

    Publication Year: 2005 , Page(s): 442 - 445
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (138 KB) |  | HTML iconHTML  

    We propose a 2D receiver structure for MC-CDMA systems with a reduced-rank multistage Weiner filter. The 2D space-frequency receiver does not require angle of arrival estimation and explicit channel estimation. Due to the faster convergence property of the reduced-rank processing, it outperforms MMSE-based receivers with the classical Weiner solution estimated by using a small finite number of samples. View full abstract»

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  • Microwave operation of on-chip antenna embedded in WL-CSP [RFID applications]

    Publication Year: 2005 , Page(s): 147 - 150
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (177 KB) |  | HTML iconHTML  

    An on-chip antenna for microwave operation is demonstrated. The application of wafer-level chip-scale package (WL-CSP) techniques such as dual Cu electroplating conductive layers, and thick resin layers separating the conductive layer more than 10 μm from the Si substrate, allow on-chip integration. Details of the antenna fabrication process and performance are presented. Antenna performance achieved a maximum communication range between the on-chip antenna and a transmission module of over 400 mm at a transmission signal power of 300 mW. WL-CSP techniques realize real chip-scale long communication range radio frequency identification (RFID) tags. View full abstract»

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  • Chip-capacitor loaded dual-band microstrip antenna

    Publication Year: 2005 , Page(s): 227 - 229
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (95 KB) |  | HTML iconHTML  

    In this paper, we propose a novel and simple design of using a single-layer rectangular microstrip antenna for achieving a single-feed dual-band operation. The loading of chip capacitors can further extend the capacitive loads. The results show that the frequency ratio is within the range 1.25-1.73. Details of the proposed antenna design are described, and experimental results for the obtained performance are presented and discussed. View full abstract»

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  • A wideband antenna with a folded patch feed

    Publication Year: 2005 , Page(s): 45 - 48
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (142 KB) |  | HTML iconHTML  

    The need for wireless connectivity of home, office and portable equipment has pushed for better antenna designs with a larger bandwidth. The microstrip patch antenna is a very popular choice for many wireless communications devices because of its low profile, light weight, and low cost. However, the impedance bandwidth of a conventional microstrip patch antenna is only a couple of percent. Several bandwidth enhancement techniques for microstrip patch antennas have been developed, and, recently, a new feeding method that can dramatically improve the impedance bandwidth of a patch antenna has been proposed, namely, the folded patch feed. A rectangular U-slot patch antenna with a folded patch feed is shown to have an impedance bandwidth of 53.54% (VSWR≤2) (Chiu, C.Y. et al., IEEE Antennas and Wireless Propag. Lett., vol.2, p.130-2, 2003). We propose to adopt the folded patch feed to an E-shaped patch antenna. Easier fabrication, smaller size and wider impedance bandwidth (73.78%) are achieved compared to the original design reported by Chiu, C.Y. et al. The proposed antenna suitable for mass production. View full abstract»

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  • Thin frequency selective surface (FSS) superstrate with different periodicities for dual-band directivity enhancement

    Publication Year: 2005 , Page(s): 375 - 378
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (218 KB) |  | HTML iconHTML  

    In this paper we present a novel design of a high directivity resonator antenna that utilizes a two-layered frequency selective surface (FSS) superstrate with different periodicities - as an alternative to a conventional FSS superstrate - for dual band directivity enhancement to reduce its height. Two strip dipole arrays with different periodicities are placed above and below a dielectric layer. The proposed thin FSS superstrate yields 13.1 and 19.54 dBi directivity enhancements at 8.75 GHz and 12.7 GHz, respectively, as compared to that of a patch antenna (6 dBi), while its height is only one half of that of a conventional patch antenna. View full abstract»

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  • Substrate-integrated folded waveguide slot antenna

    Publication Year: 2005 , Page(s): 307 - 309
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (93 KB) |  | HTML iconHTML  

    We show a slot antenna in a folded substrate-integrated waveguide. These waveguides have half the width of the other types of substrate-integrated waveguide. As such the present structure allows arrays of slot antennas to be more highly integrated. View full abstract»

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