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Antennas and Propagation, IEEE Transactions on

Issue 2 • Date Feb. 2013

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Displaying Results 1 - 25 of 73
  • Table of Contents

    Page(s): C1 - 498
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  • IEEE Transactions on Antennas and Propagation publication information

    Page(s): C2
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  • A Looped-Bowtie RFID Tag Antenna Design for Metallic Objects

    Page(s): 499 - 505
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    Design of a long read-range, reconfigurable operating frequency radio frequency identification (RFID) metal tag is proposed in this paper. The antenna structure consists of two nonconnected load bars and two bowtie patches electrically connected through four pairs of vias to a conducting backplane to form a looped-bowtie RFID tag antenna that is suitable for mounting on metallic objects. The design offers more degrees of freedom to tune the input impedance of the proposed antenna. The load bars, which have a cutoff point on each bar, can be used to reconfigure the operating frequency of the tag by exciting any one of the three possible frequency modes; hence, this tag can be used worldwide for the UHF RFID frequency band. Experimental tests show that the maximum read range of the prototype, placed on a metallic object, are found to be 3.0, 3.2, and 3.3 m, respectively, for the three operating modes, which has been tested for an RFID reader with only 0.4 W error interrupt pending register (EIPR). The paper shows that the simulated and measured results are in good agreement with each other. View full abstract»

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  • Study of a Low-Profile 2.4-GHz Planar Dipole Antenna Using a High-Impedance Surface With 1-D Varactor Tuning

    Page(s): 506 - 515
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    A theoretical and experimental study has been performed on a low-profile, 2.4-GHz dipole antenna that uses a frequency-selective surface (FSS) with varactor-tuned unit cells. The tunable unit cell is a square patch with a small aperture on either side to accommodate the varactor diodes. The varactors are placed only along one dimension to avoid the use of vias and simplify the dc bias network. An analytical circuit model for this type of electrically asymmetric unit cell is shown. The measured data demonstrate tunability from 2.15 to 2.63 GHz with peak gains at broadside that range from 3.7- to 5-dBi and instantaneous bandwidths of 50 to 280 MHz within the tuning range. It is shown that tuning for optimum performance in the presence of a human-core body phantom can be achieved. The total antenna thickness is approximately λ/45. View full abstract»

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  • Assembled Dual-Band Broadband Quadrifilar Helix Antennas With Compact Power Divider Networks for CNSS Application

    Page(s): 516 - 523
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    Assembled dual-band quadrifilar helix antennas (QHAs) are proposed for applications in Compass Navigation Satellite System (CNSS) of China. The assembled CNSS antennas proposed are designed specifically to meet the requirements of the system: Duplex communication service on two frequency bands (1.615 GHz and 2.492 GHz); Broad beamwitdh on radiation pattern and broad bandwidth for circularly polarization (CP) applications. In this paper, the structure of assembled CNSS QHAs is demonstrated first, which comprises of emitting and receiving QHAs with novel compact power divider networks. Then the method to control the radiation pattern of QHAs is analyzed. Moreover, the design principle of the compact power divider network to achieve broadband application is presented. In the end, the antenna was fabricated and measured. Experimental results show that the proposed assembled CNSS dual-band QHAs exhibit duplex operation, broad 3 dB beamwidth (>;180 deg), and broad 10 dB return loss bandwidth (emitting antenna 39%; receiving antenna 28%). In addition, the axial ratio is less than 1.5 on two frequency bands of the system (Uplink: 1615.68±7 MHz; Downlink: 2491.75±15 MHz). View full abstract»

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  • Flexible and Compact AMC Based Antenna for Telemedicine Applications

    Page(s): 524 - 531
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    We present a flexible, compact antenna system intended for telemedicine applications. The design is based on an M-shaped printed monopole antenna operating in the Industrial, Scientific, and Medical (ISM) 2.45 GHz band integrated with a miniaturized slotted Jerusalem Cross (JC) Artificial Magnetic Conductor (AMC) ground plane. The AMC ground plane is utilized to isolate the user's body from undesired electromagnetic radiation in addition to minimizing the antenna's impedance mismatch caused by the proximity to human tissues. Specific Absorption Rate (SAR) is analyzed using a numerical human body model (HUGO) to assess the feasibility of the proposed design. The antenna expresses 18% impedance bandwidth; moreover, the inclusion of the AMC ground plane increases the front to back ratio by 8 dB, provides 3.7 dB increase in gain, in addition to 64% reduction in SAR. Experimental and numerical results show that the radiation characteristics, impedance matching, and SAR values of the proposed design are significantly improved compared to conventional monopole and dipole antennas. Furthermore, it offers a compact and flexible solution which makes it a good candidate for the wearable telemedicine application. View full abstract»

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  • A Wearable Active Antenna for Global Positioning System and Satellite Phone

    Page(s): 532 - 538
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    A wearable multiband circularly polarized active antenna is presented for use in Global Positioning System and Iridium satellite phone applications. The square patch antenna is constructed using flexible foam and fabric substrates and conductors etched on thin copper-on-polyimide films. The feed substrate integrates a compact low-noise amplifier chip directly underneath the antenna patch. The antenna performance is studied under bending conditions and in the presence of a human body. The active antenna exhibits a gain higher than 25 dBi and a 3 dB axial ratio bandwidth exceeding 183 MHz in free-space conditions and is robust to bending and on-body placement. View full abstract»

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  • Broadband Long Rectangular Patch Antenna With High Gain and Vertical Polarization

    Page(s): 539 - 546
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    A new microstrip rectangular patch antenna with high gain and vertically polarized radiation at endfires is proposed. The antenna has a wide bandwidth with a very low profile. Such antenna is based on a long microstrip line with periodic shorting-vias along the longitudinal direction. When both ends of the line are also shorted by vias, a resonant type of antenna is constructed. Two resonant modes with similar radiation patterns are generated. By optimizing the separation of the resonate frequencies of the two modes, a wide bandwidth is achieved. Measured results show that the antenna with a profile of 0.03 wavelengths in free space and a length of about 1.25 wavelengths can produce a bandwidth of 12.48% and a maximum gain of about 9 dBi. View full abstract»

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  • RIS-Based Compact Circularly Polarized Microstrip Antennas

    Page(s): 547 - 554
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    Compact, asymmetricsymmetric-slottedslit-microstrip patch antennas on reactive impedance surface (RIS) are proposed and studied for circularly polarized (CP) radiation. The antennas consist of a slotted-slit-microstrip patch on a RIS substrate. The CP radiation with compact size is achieved by asymmetricsymmetric-slot-slit cut along the orthogonaldiagonal directions of the patch radiator. The asymmetricsymmetric-slottedslit microstrip patches on the RIS structure are used for further miniaturization of the antenna with improvement in CP radiation. The measured results of the compact asymmetric-cross slotted square patch antenna are 1.6% (2.51-2.55 GHz) for 3-dB axial ratio bandwidth, 5.2% (2.47-2.60 GHz) for 10-dB return loss bandwidth, and 3.41 dBic for gain over 3-dB axial ratio bandwidth. The overall antenna volume is 0.292λo × 0.292λo × 0.0308λo on a low cost FR4 substrate at 2.5 GHz. View full abstract»

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  • A Novel Dual Band Circularly Polarized GNSS Antenna for Handheld Devices

    Page(s): 555 - 562
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    A novel chip antenna design, which is compatible with multiple satellite-based navigation systems, is proposed for handheld devices. Several techniques were employed to provide desirable performance characteristics such as dual band operation, circularly polarized reception, small form factor, and low fabrication cost. Antenna configuration features include a surface mount antenna chip, a strip line feed that is perpendicular to the chip, a clip-shaped slit cut on the chip, and the clearance region on the ground plane. Antenna design was conducted via numerical simulations. Extensive parametric studies were carried out to associate performance features with specific antenna structures. A prototype antenna was also fabricated to verify its superior performance and validate the design procedure. View full abstract»

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  • Wideband Circularly Polarized Dielectric Bird-Nest Antenna With Conical Radiation Pattern

    Page(s): 563 - 570
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    A wideband circularly polarized (CP) antenna with a conical radiation pattern is investigated. It consists of a feeding probe and parasitic dielectric parallelepiped elements that surround the probe. Since the structure of the antenna looks like a bird nest, it is named as bird-nest antenna. The probe, which protrudes from a circular ground plane, operates in its fundamental monopole mode that generates omnidirectional linearly polarized (LP) fields. The dielectric parallelepipeds constitute a wave polarizer that converts omnidirectional LP fields of the probe into omnidirectional CP fields. To verify the design, a prototype operating in C band was fabricated and measured. The reflection coefficient, axial ratio (AR), radiation pattern, and antenna gain are studied, and reasonable agreement between the measured and simulated results is observed. The prototype has a 10-dB impedance bandwidth of 41.0% and a 3-dB AR bandwidth of as wide as 54.9%. A parametric study was carried out to characterize the proposed antenna. Also, a design guideline is given to facilitate designs of the antenna. View full abstract»

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  • CRLH Leaky Wave Antenna Based on ACPS Technology With 180 ^{\circ} Horizontal Plane Scanning Capability

    Page(s): 571 - 577
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    This study presents a novel composite right/left-handed (CRLH) leaky wave antenna (LWA) with horizontal plane scanning capability. This LWA consists of 10 CRLH unit cells and coplanar waveguide to coplanar stripline transitions. The proposed balanced CRLH unit cell is based on an asymmetric coplanar stripline structure (ACPS). The parameters of the CRLH unit cell can be determined analytically, enabling easy modification for any other frequency band. Because of its planar and horizontal plane scanning property, the proposed design can also be extended to a sector-shaped multisection LWA, achieving a scanning range of more than 180° in the horizontal plane. By varying the operating frequency, the CRLH leaky wave antenna shows the continuously beam-scanning property from backward to forward in the horizontal plane. A 10-cell prototype exhibits the beam-scanning capability in the horizontal plane, and a 20-cell multisection sector-shaped LWA confirms the approach of designing the wide-range beam-scanning LWA. Experimental results show that the proposed design is in good agreement with the simulation. The planar and low-profile characteristics of the novel CRLH LWA make it suitable for integration with other microwave circuits, and can be applied to applications that require a wider beam-scanning range. View full abstract»

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  • Dual-Function Radiating Glass for Antennas and Light Covers—Part I: Omnidirectional Glass Dielectric Resonator Antennas

    Page(s): 578 - 586
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    The dual-function glass dielectric resonator antenna (DRA) that simultaneously serves as a light cover is investigated for the first time. This paper is the first part, which demonstrates the idea using omnidirectional hollow rectangular glass DRAs. Both linearly polarized (LP) and circularly polarized (CP) designs are given. The glass DRA can generate CP fields by adding metallic patches onto its side walls, with a 3-dB axial ratio bandwidth of ~ 7%. To obtain an entirely light-transmissible CP glass DRA, conducting indium tin oxide (ITO) patches are used in place of the metallic patches. For each of the LP and CP designs, powered light emitting diodes (LEDs) are placed inside the hollow region of the glass DRA to serve as the light source. It is shown that practically the lighting and antenna parts do not interfere with each other. The reflection coefficient, axial ratio (CP designs only), radiation patterns, and antenna gains of the proposed LP and CP antennas are studied, and good agreement between measured and simulated results is observed. View full abstract»

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  • Dual-Function Radiating Glass for Antennas and Light Covers—Part II: Dual-Band Glass Dielectric Resonator Antennas

    Page(s): 587 - 597
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    This paper is the second part of our study that investigates using glass dielectric resonator antennas (DRAs) as light covers. To begin, designs of dual-band hemispherical DRAs are investigated for the first time. Both broadside and omnidirectional dual-band DRAs are included in the study. The former makes use of the broadside TE111 and TE112 modes of a hollow hemispherical DRA, whereas the latter utilizes the endfire TM101 and TM103 modes of a solid hemispherical DRA. New design formulas that determine the radii of the two dual-band hemispherical DRAs are found. To demonstrate the usefulness of the formulas, two dual-band hemispherical DRAs for WLAN/WiMAX applications were designed and fabricated using K9 glass. ANSYS HFSS was used to simulate the DRAs, and the results agree reasonably well with our measurements. Results of using the DRAs as light covers are reported. View full abstract»

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  • Dual Circularly Polarized Spherical Phased-Array Antenna for Spacecraft Application

    Page(s): 598 - 605
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    Design aspects of an active spherical phased-array antenna (SPAA) operating in dual circularly polarized (CP) mode are discussed here. Dual CP configuration with good cross-polarized isolation enables frequency reuse using polarization diversity. This design also implements sharing of the resources like amplifiers and phase shifters in an optimal way to reduce mass, power requirement, and cost of the antenna. The antenna is hemispherical in shape and maintains required effective isotropic radiated power (EIRP) over a hemispherical coverage area. Detailed analysis including the effect of failure of a few of the elements of the array and the measured results of the antenna at X-band are discussed here. This antenna has been used for transmission of payload data from a low Earth orbit satellite of ISRO. View full abstract»

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  • A Shared-Aperture Dual-Band Planar Array With Self-Similar Printed Folded Dipoles

    Page(s): 606 - 613
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    Light-weight antenna arrays require utilizing the same antenna aperture to provide multiple functions (e.g., communications and radar) in separate frequency bands. In this paper, we present a novel antenna element design for a dual-band array, comprising interleaved printed dipoles spaced to avoid grating lobes in each band. The folded dipoles are designed to be resonant at octave-separated frequency bands (1 and 2 GHz), and inkjet-printed on photographic paper. Each dipole is gap-fed by voltage induced electromagnetically from a microstrip line on the other side of the substrate. This nested element configuration shows excellent corroboration between simulated and measured data, with 10-dB return loss bandwidth of at least 5% for each band and interchannel isolation better than 15 dB. The measured element gain is 5.3 to 7 dBi in the two bands, with cross-polarization less than -25 dBi. A large array containing 39 printed dipoles has been fabricated on paper, with each dipole individually fed to facilitate independent beam control. Measurements on the array reveal broadside gain of 12 to 17 dBi in each band with low cross-polarization. View full abstract»

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  • Fast Co-Polar and Cross-Polar 3D Pattern Synthesis With Dynamic Range Ratio Reduction for Conformal Antenna Arrays

    Page(s): 614 - 626
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    This paper presents a fast method for conformal antenna arrays that enables the synthesis of 3D co-polar and cross-polar patterns, simultaneously reducing the dynamic range ratio (DRR) of the array excitations. The power synthesis problem is reduced to a field synthesis one by introducing two auxiliary phase patterns: one for the co-polar pattern and the other for the cross-polar pattern. The problem is then iteratively solved with respect to the two auxiliary phase patterns and to the array excitations. A modified version of the method is also proposed, for the particular case where the DRR reduction is not required, obtaining a further strong reduction of the computational time. View full abstract»

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  • Fast Pencil Beam Pattern Synthesis of Large Unequally Spaced Antenna Arrays

    Page(s): 627 - 634
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1974 KB) |  | HTML iconHTML  

    Reducing the computational cost of large array pattern synthesis is attractive in many applications. In this paper, a fast pencil beam pattern synthesis method for large nonuniform antenna arrays is proposed. This method is based on an interpolation in a least square sense and iterative fast Fourier transform (FFT), i.e., interpolate the nonuniform distributed elements into uniform virtual elements, and then apply FFT to synthesis the uniform array. Thanks to the efficiency of FFT, the proposed method is much faster and can handle much larger arrays than the existing methods. To guarantee the interpolation accuracy, the choice of the interpolation parameters is discussed. Both linear and planar nonuniform array examples are shown to validate the advantages of the proposed method. View full abstract»

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  • Design and Validation of a Reconfigurable Single Varactor-Tuned Reflectarray

    Page(s): 635 - 645
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    An aperture-coupled reflectarray element giving a full phase tuning range with a single varactor diode is proposed in this paper for pattern reconfigurability applications. The full phase agility is achieved by a proper optimization of the phase tuning line, thus providing an alternate inductive/capacitive effect able to avoid the use of two varactor diodes, usually adopted in similar existing configurations. The proposed active element structure is adopted to design a demonstrative reflectarray prototype of 3 × 15 radiators. Furthermore, an own synthesis procedure is applied to obtain the proper biasing voltages giving the prescribed H-plane field. Test examples of beam-scanning, multibeam, and shaped-beam patterns are discussed to demonstrate the effectiveness of the approach. View full abstract»

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  • A Compact Dual-Band Pattern Diversity Antenna by Dual-Band Reconfigurable Frequency-Selective Reflectors With a Minimum Number of Switches

    Page(s): 646 - 654
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    A novel compact dual-band pattern diversity antenna is proposed. Dual-band reconfigurable frequency-selective reflectors are designed and applied to form a right-angle corner reflector antenna with reconfigurable patterns. With only one switch, the reconfigurable frequency-selective reflector can be controlled to be transmissive or reflective to vertically polarized waves at 2.45 and 5.25 GHz. By changing the combinations of the switch states, multiple patterns can be obtained. A dual-band feeding antenna designed via using the coupling effects is made to achieve well-matching conditions in all circumstances corresponding to various switch states at both frequencies. The measured results show good agreement with the calculated ones and demonstrate good pattern diversity virtues. View full abstract»

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  • A Self-Adapting Flexible (SELFLEX) Antenna Array for Changing Conformal Surface Applications

    Page(s): 655 - 665
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    A phased-array test platform for studying the self-adapting capabilities of conformal antennas is developed and presented. Specifically, a four-port 2.45-GHz receiver with voltage controlled phase shifters and attenuators is designed along with four individual printed microstrip patch antennas attached to a conformal surface. Each antenna is connected to the corresponding receiver port with a flexible SMA cable. It is shown that with appropriate phase compensation, the distorted radiation pattern of the array can be recovered as the surface of the conformal array changes shape. This pattern recovery information is then used to develop a new self-adapting flexible 1 × 4 microstrip antenna array with an embedded flexible sensor system. In particular, a flexible resistive sensor is used to measure the deformation of the substrate of a conformal antenna array, while a sensor circuit is used to measure the changing resistance. The circuit then uses this information to control the individual voltage of the phase shifters of each radiating element in the array. It is shown that with appropriate phase compensation, the radiation properties of the array can be autonomously recovered as the surface of the flexible array changes shape during normal operation. Throughout this work, measurements are shown to agree with analytical solutions and simulations. View full abstract»

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  • Electronically Sweeping-Beam Antenna Using a New Cylindrical Frequency-Selective Surface

    Page(s): 666 - 676
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    An electronically sweeping radiation-pattern antenna using a new active cylindrical frequency-selective surface (ACFSS) is presented for 2.45-GHz operating frequency. The ACFSS screen is constructed by a new reconfigurable hybrid unit cell, providing more freedom to control the antenna radiation characteristics. A design guideline based on the reflector antenna principles is also introduced to estimate the overall dimensions of the antenna geometry, and then the required number of unit cells for the ACFSS surface is calculated. Furthermore, to confirm the proposed design guideline, the performance of the designed antenna is compared to three conventional reflector antennas constructed with solid perfect electric conductors. The achieved simulation results for these antennas are carefully examined and the impact of the FSS surface on enhancing the ACFSS antenna gain is discussed. Moreover, parametric studies for the crucial dimensions of the unit cell are also presented to demonstrate the effect of each parameter on the antenna radiation characteristics. To completely examine the achieved results, the transmission coefficient response of the applied FSS sheet is experimentally assessed, and the antenna measured parameters are accordingly interpreted. View full abstract»

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  • Frequency Selective Surfaces for Pulsed High-Power Microwave Applications

    Page(s): 677 - 687
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    We examine the peak power handling capability of a class of miniaturized-element frequency selective surfaces composed entirely of non-resonant constituting elements. The effects of various design parameters on the peak power handling capability of these structures are investigated using electromagnetic simulations and methods for increasing their peak power handling capability are proposed. These methods are used to design a high-power microwave (HPM) frequency selective surface (FSS), which is expected to be capable of handling extremely high peak power levels. The power handling capabilities of these devices are also experimentally investigated using an HPM source with a frequency of 9.382 GHz, a peak power of 25 kW, and a pulse length of 1 μs. Unit cells of various FSSs under investigation are placed in a waveguide and excited with pulses with variable power levels. The time-domain reflection and transmission coefficients of each device is measured at various power levels and the power level at which the device breaks down is determined. The results of these experimental investigations follow the same trend observed in the simulations. Additionally, our experiments demonstrate that the HPM FSSs developed in this work are indeed capable of handling extremely high peak power levels. View full abstract»

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  • Investigation of Virtual Array Antennas With Adaptive Element Locations and Polarization Using Parabolic Reflector Antennas

    Page(s): 688 - 699
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    A novel multi-phase center parabolic reflector antenna is investigated that utilizes a single hardware system to displace the antenna phase center location electronically in any direction, while generating identical broadside secondary radiation patterns at the far-field region to convert the reflector antenna into a virtual array. The primary feed is a dual-mode circular waveguide operating at the TE11 and TE21 type modes. The combination of these modes with different polarizations, amplitude ratios, and phase differences are considered. It is shown that the phase center location of the antenna can be displaced from the physical center of its geometry by changing the excitation amplitude and phase of each mode, and more importantly by employing different mode orientations. This results in a virtual array antenna with element locations that can be displaced in any direction, depending on the polarization of each mode, by a simple signal processing procedure without mechanically moving the antenna itself. The antenna developed using this technique has potential applications as a transceiver antenna in precise positioning systems, radars with moving platforms, and virtual smart antennas. The operating frequency is 10 GHz. The proposed multi-phase center virtual antenna concept is verified experimentally exhibiting excellent agreement with the numerical results. View full abstract»

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  • Wideband Fan-Beam Low-Sidelobe Array Antenna Using Grounded Reflector for DECT, 3G, and Ultra-Wideband Wireless Applications

    Page(s): 700 - 706
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    A low-sidelobe fan-beam wideband linear array antenna employing a nonparasitic grounded reflector is presented. This fan-beam antenna is achieved using a six-element conventional planar monopole array antenna and feed network, which together produce sidelobes at - 26 dB. Dolph-Tschebyscheff distribution is employed, and a broadband array feed network is designed to satisfy beneficial input impedance bandwidth requirements in the frequency range 1.7-2.2 GHz. Therefore, this array covers applications of GSM-DCS2, DECT, and 3G. Combining planar monopole antenna as an array with nonparasitic grounded reflector allows an advantageous fan beam pattern to be generated. H-plane 3-dB beamwidths are controllable using grounded reflector height. In addition, the results are compared with and without reflector array antenna. View full abstract»

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IEEE Transactions on Antennas and Propagation includes theoretical and experimental advances in antennas.

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Editor-in-Chief                                                 Kwok W. Leung