Notification:
We are currently experiencing intermittent issues impacting performance. We apologize for the inconvenience.
By Topic

Antennas and Propagation Magazine, IEEE

Issue 4 • Date Aug 1995

Filter Results

Displaying Results 1 - 7 of 7
  • Supergain antennas: possibilities and problems

    Publication Year: 1995 , Page(s): 13 - 26
    Cited by:  Papers (4)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1092 KB)  

    In principle, any desired amount of gain can be developed from an antenna of arbitrary size. The phenomena of high gain from very small antennas is called “supergain”. To see why this statement might be so, the author recalls the construction used in optics, known as Huygens' principle. This states that every point on a wavefront can be regarded as a source of radiation. At the end of a short period of time, the envelope of all of these individual wavelets forms the new wavefront. For example, this construct explains why a shadow is not perfectly sharp, and why interference fringes form. End fire antennas, dipole antennas, Yagi antennas and quad antennas are examined View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Analysis of aperture-coupled microstrip-Antenna and circuit structures using the transmission-line-matrix method

    Publication Year: 1995 , Page(s): 27 - 37
    Cited by:  Papers (8)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (948 KB)  

    The transmission-line-matrix method is a numerical technique for solving Maxwell's equations in the presence of complex environments. A general-purpose simulation program, based on the three-dimensional symmetrical-condensed TLM model, is presented. Previous applications of the simulation program include the analysis of half-space and remote-sensing problems, and calculation of the radar cross section of finite-sized conducting materials and objects. The simulation program is applied to the characterization of aperture-coupled microstrip structures. Numerical results, pertaining to the analysis of aperture-coupled microstrip lines, offset-aperture-coupled microstrip lines, and aperture-coupled microstrip-patch antennas, indicate the accuracy and utility of the program for analyzing aperture-coupled microstrip configurations. A discussion of the accuracy and efficiency of the approach is included, with limitations and possible improvements View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Phase difference between linear components of elliptically polarized waves from amplitude only measurements

    Publication Year: 1995 , Page(s): 69 - 70
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB)  

    An amplitude-only measurement setup can measure the axial ratio and tilt angle of an elliptically polarized wave. During design, both the amplitude and phase of the linear components are needed. The equipment measures the amplitudes directly. A nomograph, using the well-known relationships between polarization components determines the phase of the vertical component relative to the horizontal. The value of the nomograph goes beyond the stated objective, because it shows the relationships between the variables. The nomograph gives both the requirements for good circularity, and the sensitivity of the various parameters View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A selective survey of the finite-difference time-domain literature

    Publication Year: 1995 , Page(s): 39 - 57
    Cited by:  Papers (56)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1772 KB)  

    The finite-difference time-domain (FDTD) method is arguably the most popular numerical method for the solution of problems in electromagnetics. Although the FDTD method has existed for nearly 30 years, its popularity continues to grow as computing costs continue to decline. Furthermore, extensions and enhancements to the method are continually being published, which further broaden its appeal. Because of the tremendous amount of FDTD-related research activity, tracking the FDTD literature can be a daunting task. We present a selective survey of FDTD publications. This survey presents some of the significant works that made the FDTD method so popular, and tracks its development up to the present-day state-of-the-art in several areas. An “on-line” BibTEX database, which contains bibliographic information about many FDTD publications, is also presented View full abstract»

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

    Publication Year: 1995 , Page(s): 82 - 86
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (416 KB)  

    The order of an electromagnetics algorithm or code is defined by the rate at which the CPU time, and memory requirements CCPU=O(fα) and Cm=O(fβ ), respectively-grow with frequency. Knowledge of this information helps in the prediction of computer-run times and memory requirements for problems of interest. This paper presents a methodology for determining the computational and memory orders of a code. These results are presented for a finite-volume time-domain (FVTD) code and for a method-of-moments (MoM) code. Computer-resource requirements are plotted for computer runs that calculate the bistatic radar cross section (RCS) for spheres of different electrical sizes, within a set error level from the Mie-series solution. These plots are used to calculate the computational and memory orders of the codes View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Excitation of a conducting half-space by a toroidal coil

    Publication Year: 1995 , Page(s): 72 - 74
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (196 KB)  

    The possibility exists that a non-contacting “vertical-electrical dipole”source could be devised, to excite both horizontal and vertical currents in the subsurface. The scheme is quite simple, but it seems to have been overlooked or, at least, not disclosed, hitherto. The idea is to employ a toroidal coil carrying an alternating current, which is located in or just above the air/earth interface. As shown, when the diameter of the toroid is small compared to the distance to the observer, the effective source is effectively a vertical-electric dipole. This may be obvious to some, but the situation has some interesting complications, because of the presence of the interface. The pertinent analysis is outlined View full abstract»

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

    Publication Year: 1995 , Page(s): 7 - 12
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (488 KB)  

    A brief history of the development of MININEC is presented. Differences between MININEC and NEC are discussed. A new version, MININEC Professional for Windows, is described, along with the application of this new version. The original purpose of the code was to provide a tool for the rapid analysis of simple, relatively small (in terms of wavelengths) antenna structures 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
Mahta Moghaddam