By Topic

Antennas and Propagation Magazine, IEEE

Issue 6 • Date Dec. 2008

Filter Results

Displaying Results 1 - 25 of 65
  • Front cover - IEEE Antennas and Propagation Magazine

    Page(s): C1
    Save to Project icon | Request Permissions | PDF file iconPDF (698 KB)  
    Freely Available from IEEE
  • Table of contents

    Page(s): 3
    Save to Project icon | Request Permissions | PDF file iconPDF (314 KB)  
    Freely Available from IEEE
  • Information for contributors

    Page(s): 4
    Save to Project icon | Request Permissions | PDF file iconPDF (314 KB)  
    Freely Available from IEEE
  • Magazine Staff

    Page(s): 5 - 6
    Save to Project icon | Request Permissions | PDF file iconPDF (397 KB)  
    Freely Available from IEEE
  • AP-S Officers and Administrative Committee

    Page(s): 7
    Save to Project icon | Request Permissions | PDF file iconPDF (978 KB)  
    Freely Available from IEEE
  • Editor's comments

    Page(s): 8 - 228
    Save to Project icon | Request Permissions | PDF file iconPDF (3036 KB)  
    Freely Available from IEEE
  • President's Message

    Page(s): 8 - 9
    Save to Project icon | Request Permissions | PDF file iconPDF (665 KB)  
    Freely Available from IEEE
  • 2009 IEEE Antennas and Propagation Society Membership Application

    Page(s): 10
    Save to Project icon | Request Permissions | PDF file iconPDF (231 KB)  
    Freely Available from IEEE
  • IEEE International Symposium on Antennas and Propgation and USNC/URSI National Radio Science Meeting

    Page(s): 11
    Save to Project icon | Request Permissions | PDF file iconPDF (542 KB)  
    Freely Available from IEEE
  • 2009 IEEE International Symposium on Antennas and Propagation and USNC/URSI-Put Carolina on your mind!

    Page(s): 12
    Save to Project icon | Request Permissions | PDF file iconPDF (542 KB)  
    Freely Available from IEEE
  • 2009 IEEE International Symposium on Antennas and Propagation and USNC/URSI National Radio Science Meeting - Steering Committee

    Page(s): 13
    Save to Project icon | Request Permissions | PDF file iconPDF (542 KB)  
    Freely Available from IEEE
  • Social Events and Companion Tours

    Page(s): 14 - 17
    Save to Project icon | Request Permissions | PDF file iconPDF (3896 KB)  
    Freely Available from IEEE
  • 2009 IEEE AP-S International Symposium & USNC/URSI

    Page(s): 18 - 19
    Save to Project icon | Request Permissions | PDF file iconPDF (332 KB)  
    Freely Available from IEEE
  • AP-S Election Results

    Page(s): 38
    Save to Project icon | Request Permissions | PDF file iconPDF (280 KB)  
    Freely Available from IEEE
  • Metallized foams for fractal-shaped microstrip antennas

    Page(s): 20 - 37
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (24324 KB) |  | HTML iconHTML  

    An antenna manufacturing process using metallized foams is presented. A microstrip-patch antenna, inspired by the Koch island geometry, embedded in a rectangular cavity is built and tested. All the metallic parts of the antenna (patch, cavity, and feeding probe) were metaliized on the foam, resulting in a low-weight and low-complexity antenna structure. The results of return loss, directivity as a function of frequency, radiation pattern for several modes, and radiation efficiency have been compared with simulated data, resulting in very good agreement. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Analysis of dual-reflector antennas with a reflectarray as subreflector

    Page(s): 39 - 51
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6441 KB) |  | HTML iconHTML  

    In this paper, a modular technique is described for the analysis of dual-reflector antennas using a reflectarray as a subreflector. An antenna configuration based on a sub-reflectarray and a parabolic main reflector provides better bandwidth than a single reflectarray, and has a number of advantages compared with a conventional dual-reflector antenna. Examples include the possibility of beam shaping by adjusting the phase on the sub-reflectarray, and potential capabilities to scan or reconfigure the beam. The modular technique implemented for the antenna analysis combines different methods for the analysis of each part of the antenna. First, the real field generated by the horn is considered as the incident field on each reflectarray element. Second, the reflectarray is analyzed with the same technique as for a single reflectarray, i.e., considering local periodicity and the real angle of incidence of the wave coming from the feed for each periodic cell. Third, the main reflector is analyzed using the Physical Optics (PO) technique, where the current on the reflector surface is calculated by summing the radiation from all the reflectarray elements. Finally, the field is calculated on a rectangular periodic mesh at a projected aperture, and then a time-efficient fast Fourier transform (FFT) algorithm is used to compute the radiation pattern of the antenna. The last step significantly improves the computational efficiency. However, it introduces a phase error, which reduces the accuracy of the radiation patterns for radiation angles far away from the antenna's axis. The phase errors have been evaluated for two integration apertures. It has been demonstrated that accurate patterns are obtained in an angular range of plusmn6deg, which is sufficient for large reflectors. The method of analysis has been validated by comparing the results with simulations obtained from GRASP8. Finally, the theoretical beam-scanning performance of the antenna is analyzed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Design of a broadband dipole in close proximity to an EBG ground plane

    Page(s): 52 - 64
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (12021 KB) |  | HTML iconHTML  

    One of the known advantages of an electromagnetic bandgap (EBG) ground plane is the fact that a straight-wire dipole can be located parallel and in very close proximity to the ground plane. For such a structure and geometry, a reasonable impedance match to 50 n) can be achieved with more bandwidth than when the dipole is located in close proximity to a PEC ground plane. However, in addition to impedance, radiation-pattern properties must be considered when evaluating the antenna's overall performance and usable bandwidth. Here, we consider the performance properties of a folded bowtie dipole element in close proximity to an EBG ground plane, with emphasis on examining the bandwidth and pattern characteristics. We demonstrate that a dipole element can be designed to exhibit a matched input impedance over approximately a 1.4:1 bandwidth with respect to a 50 n characteristic impedance, when located in close proximity to the EBG ground plane. While the shape of the radiation pattern of the antenna remains relatively unchanged over much of this operating bandwidth, we show that the usable bandwidth of the antenna-EBG combination is limited to approximately 1.5:1, due to pattern degradation at both the lower and upper frequencies. Details of the design approach and feed structure used to match the impedance of the dipole to 50 fl are discussed. Finally, we show that with this element design, the reflection phase bandwidth of the EBG ground plan-e does not limit the matched impedance bandwidth of the antenna. A -portion of ,t ,he work detailed here was presented at the 2005 Antenna Applications Symposium. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Calculation of the propagation loss in urban radio-access systems

    Page(s): 65 - 70
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1898 KB) |  | HTML iconHTML  

    A proposition for a new empirical propagation model, in the form of four formulas appropriate for characteristic types of the urban environment, is outlined. A measurement verification of some well-known models and specification of the propagation environmental are first described. Taking into account about nineteen thousand measurement cases, a new model obtained by multidimensional regression analysis is than presented. Finally, the practical usefulness of the model for radio system design analysis is discussed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A dual-polarized antenna with pattern diversity

    Page(s): 71 - 79
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4787 KB) |  | HTML iconHTML  

    An antenna that is capable of exciting four different kinds of linearly polarized waves by four independent feeding ports across an overlapped frequency band is presented. The four polarizations embrace the x and y polarized waves, which have broadside patterns, and the thetas and phi-polarized waves, which have conical patterns. The antenna can perform as a dual-polarized antenna for pattern diversity (broadside or conical) applications. The x and y polarizations (TM11 mode) and the thetas polarization (TM01 mode) are achieved by exciting a circular patch with four shorting posts and five L-shaped probe fees. The phi polarization is achieved by exciting four slots cut on the patch to produce radial magnetic currents. The performance of the antenna is studied numerically and experimentally. A prototype antenna was built, and the four polarizations overlapped at about 2.1 GHz. The antenna attained a gain of about 4 dBi for the two conical polarizations, and a gain of about 11 dBi for the two broadside polarizations. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Development and testing of a 10 GHz phased-array cylindrical-antenna transmitting system incorporating a least-squares radiation-pattern synthesis technique

    Page(s): 80 - 88
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6525 KB) |  | HTML iconHTML  

    This research presents the development and testing procedures for an experimental phased-array cylindrical-antenna transmitting system, operating at 10 GHz. The antenna-element excitation phases are set at the intermediate-frequency stage, and are determined by using a least-squares radiation-pattern synthesis technique. The antenna-element excitation amplitudes are taken to be equal and fixed. The system provides steerable main lobes and nulls at predefined directions, including control of the sidelobes at specified levels. It can be used for communications and radar applications with interference-rejection requirements. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Accuracy Analyses of Synthesized-Reference-Wave Holography for Determining Antenna Radiation Characteristics

    Page(s): 89 - 98
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3768 KB) |  | HTML iconHTML  

    Synthesized-reference-Wave holographic techniques offer relatively simple and cost-effective measurements of antenna radiation characteristics, and reconstruction of complex aperture fields using near-field intensity-pattern measurements. These methods allow utilization of the advantages of the methods for probe compensation for near-field amplitude and phase measurements for planar and cylindrical scanning, including accuracy analyses. Accuracy analyses using mathematical models considering random processes with correlation intervals are presented. Numerical simulations, taking into account random as well as deterministic errors and the processing of measurement statistics, are also presented. It is demonstrated that the given analyses correspond to our measurements and/or numerical simulations. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Chapter News

    Page(s): 100 - 102
    Save to Project icon | Request Permissions | PDF file iconPDF (3052 KB)  
    Freely Available from IEEE
  • A compact MIMO antenna for wireless communication

    Page(s): 104 - 107
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2306 KB)  

    This paper presents the design of a 2.65 GHz MIMO antenna with three equilateral triangular microstrip patches as the antenna elements. The wide-beam characteristics of a triangular-patch antenna, combined with the high gain of each antenna element, improve the SNR and interference rejection of the MIMO system. Through the analysis of mutual coupling and correlation between each pair of antenna ports, it is shown that the antenna achieves good polarization and directivity diversity. A high diversity gain can therefore be achieved. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Reflector Rim and Feed Considerations for Simple Switched-Beam Antenna Prototype

    Page(s): 108 - 113
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3534 KB) |  | HTML iconHTML  

    A simple, optimized, and easily constructed reflector-rim geometry for protyping purposes is presented as a substitute for the more cumbersome elliptical rim. The design procedure for the switched-beam antenna studied is also described. The elliptical rim shape is approximate by cutting a circular rim with six straight lines. The circular rim is first cut along two symmetrically placed parallel lines. The corners of the resulting rim are then mitered along tangent lines of the ellipse being approximated. Different designs are compared, using relative torques as estimates of wind loading. According to the simulation results, the proposed rim shape resembles an elliptical rim well in terms of beamwidth and sidelobe level. Designed to have gain equal to an elliptical reflector, the wind loading of the narrowed and mitered reflector increauses only by 5%. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Comments on "Measuring the impedance of balanced antennas by an s-parameter method"

    Page(s): 113 - 114
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3534 KB) |  | HTML iconHTML  

    This paper presents a measurement procedure for determining the impedance of balanced antennas by an S-parameter method. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

The IEEE Antennas and Propagation Magazine covers all areas relating to antenna theory, design, and practice.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
W. Ross Stone