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Antennas and Propagation, IEEE Transactions on

Issue 3 • Date March 1985

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Displaying Results 1 - 18 of 18
  • [Front cover and table of contents]

    Publication Year: 1985 , Page(s): 0
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    Freely Available from IEEE
  • Correction to "Effect of jammer power on the performance of adaptive arrays"

    Publication Year: 1985 , Page(s): 355
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    First Page of the Article
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  • Electric surface current model for the analysis of microstrip antennas on cylindrical bodies

    Publication Year: 1985 , Page(s): 295 - 300
    Cited by:  Papers (56)
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    An approach to the analysis of microstrip antennas on cylindrical bodies is presented. The printed radiator is replaced by as assumed surface current distribution, and the fields are solved taking into account the presence of the dielectric layer and the metallic cylinder. Calculation takes place in the Fourier domain. The far field, calculated asymptotically from this solution, is used to get the radiation patterns of the wraparound antenna for any dielectric and the half-wavelength patch for \epsilon_{r} = 1 . View full abstract»

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  • Operator-valued transmission lines as models of a horizontally layered earth under transient two-dimensional electromagnetic excitation

    Publication Year: 1985 , Page(s): 346 - 350
    Cited by:  Papers (3)
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    A new method of computing the transient behavior of a horizontally layered earth under two-dimensional electromagnetic excitation is presented. The earth's conductivity, magnetic permeability, and electric permittivity are assumed to vary only with depth, but those variations are allowed to be quite arbitrary. Displacement current is not neglected. After discretization of Maxwell's equations, the earth is modeled by infinite RLC electrical networks. No truncations of those networks are invoked during the computational procedure. Instead, those networks are viewed as infinite ladder networks of Hilbert ports, that is, as operator-valued lumped transmission lines, and the computations are based upon the recently devised theory of such systems. This analysis yields a new surface impedance operator, which provides a considerably more comprehensive representation of the earth's behavior than does the Tikhonov-Cagniard surface impedance. For example, the Tikhonov-Cagniard surface impedance is applicable only when the electric or magnetic fields vary slowly or linearly with respect to horizontal displacements. The surface-impedance operator derived herein does not require those restrictions; only quadratic summability and Laplace transformability are needed. View full abstract»

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  • Mirror antenna dual-band lightweight mirror design

    Publication Year: 1985 , Page(s): 286 - 294
    Cited by:  Papers (5)  |  Patents (1)
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    The mirror antenna, sometimes called an inverse Cassegrain antenna, is used in modern radar systems where efficient wide angle scan is required in combination with light weight and small size. Although previous applications have been single band, an additional advantage of the mirror antenna is that it is practical to implement dual-band configurations which can greatly enhance the capability of radar or other radiating systems. The most difficult part of a dual-band mirror antenna design is the 90\deg polarization rotating mirror (half-wave plate). The challenge is to achieve effective performance at two bands and maintain that performance over a wide range of aspect angle. Basic mirror antenna operation and design and fabrication techniques for a dual-band half-wave plate mirror are described. The solution for design parameters is derived for perfect 90\deg polarization rotation at a given aspect angle for each of the two bands. The design approach includes a process for optimizing the design for the full desired range of aspect angles. Practical fabrication considerations are discussed along with inclusion of the effects of capacitive susceptance of a protective mirror coating in the design theory. Theoretical performance is compared with measurements of mirror samples. View full abstract»

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  • Element pattern of an axial dipole in a cylindrical phased array, Part I: Theory

    Publication Year: 1985 , Page(s): 259 - 272
    Cited by:  Papers (17)
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    Cylindrical array antennas are attractive for applications requiring uniform 360\deg azimuthal pattern performance. For very low sidelobe or precise angle measurement designs, an accurate knowledge of the mutually coupled element pattern becomes important. A modal solution is presented for an element pattern in a periodic array of axial dipole radiators placed coaxially over a circular cylindrical ground. This solution avoids the problems associated with asymptotic appproaches and displays a number of advantages: 1) it is exact, subject only to truncation errors; 2) it is uniformly valid in all spatial regions for both rectangular and, with a simple modification, for triangular isosceles lattice configurations; and 3) it provides absolute gain information. The analysis is presented along with numerical results for representative parameter values, selected to illustrate the various trade-offs. Comparison with published data employing the asymptotic approach and with planar array results is given. View full abstract»

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  • Element pattern of an axial dipole in a cylindrical phased array, Part II: Element design and experiments

    Publication Year: 1985 , Page(s): 273 - 278
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    The design and construction of a cylindrical array of axial dipoles is described. Dipole pattern amplitude measurements performed over practical scan and frequency ranges show excellent agreement with theoretically predicted results. Dipole pattern phase, feed line effects and radiator match are also discussed. These results provide strong evidence of the correctness of the analysis and numerical results presented in Part I of this paper, and furnish a firm basis for accurate prediction of array performance. View full abstract»

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  • Analysis of cylindrical antennas--A spectral iteration technique

    Publication Year: 1985 , Page(s): 251 - 258
    Cited by:  Papers (8)
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    The cylindrical antenna problem has been tackled using the spectral iteration technique. An iterative scheme is employed for improving on an initially assumed form of the current distribution. Use is made of the fast Fourier transform (FFT) algorithm, and the cumbersome process of matrix inversion is circumvented. Consequently, this method is capable of handling a larger number of unknown coefficients in the expansion of the current distribution. Furthermore, it provides a convenient means of testing for the satisfaction of the boundary conditions on the surface of the antenna. Convergence criteria for the iteration process have been established and the use of an acceleration procedure is illustrated. Different types of source models have been investigated, and the convergence of both local and nonlocal parameters is also discussed. View full abstract»

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  • Instantaneous frequency scaling of rain attenuation at 11.6-17.8 GHz with SIRIO data

    Publication Year: 1985 , Page(s): 335 - 337
    Cited by:  Papers (2)
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    The ratio of simultaneous attenuation measurements performed at 11.6 and 17.8 (or 17.0 GHz) with the Italian satellite SIRIO is discussed. The main application of this information is in the field of the "up-path power control" in earth-space telecommunication systems for which the requirement of estimating the uplink attenuation form measurements on the downlink will probably be taken into consideration as a tool to keep constant the total power received on board. The analysis shows that the average ratio between attenuations at 17.8 and 11.6 GHz, conditioned to the downlink attenuation (11.6 GHz) tends to decrease slightly with attenuation; it turns out to be very close to the ratio between equiprobable values of attenuation computed from the concurrent cumulative distributions (long-term frequency scaling ratio); the standard deviation is of the order of 10 percent of the average value and also exhibits some tendency to decrease; both the overall cumulative distributions and the conditional ones are well fitted by log-normal probability models with standard deviation (of the natural logarithm) constant and equal to 0.13-0.14 up to 5.5 dB in the downlink attenuation. View full abstract»

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  • Broadside radar cross section of the perfectly conducting cube

    Publication Year: 1985 , Page(s): 321 - 329
    Cited by:  Papers (11)
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    The broadside radar cross section (RCS) of the perfectly conducting cube is predicted from arbitrarily low to arbitrarily high frequencies, and compared to measured data taken for cube side lengths ranging from 0.15 to 4 wavelengths. The predicted and measured RCS curves agree to within the estimated experimental limits of accuracy of \pm 1 dB. At low frequencies the magnetic-field integral equation was "augmented" to eliminate its spurious homogeneous solutions and thus to produce high accuracy beyond the resonance region up through the intermediate frequency range. At high frequencies the conventional diffraction solution was "enhanced" to produce high accuracy down through the intermediate frequency range into the resonance region. Close agreement between these two very different theoretical solutions in the intermediate frequency range confirmed the validity of each solution and permitted calculation of reliable curves for the amplitude and phase of the backscattered far field versus frequency. View full abstract»

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  • A technique to estimate the relative gains, tuning phases, and RE phase shifts of the elements of a phased-array radar

    Publication Year: 1985 , Page(s): 244 - 250
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    An in-situ technique to estimate the following parameters of a phased-array antenna is described: 1) the relative array-element excitation voltages, 2) the array-element tuning phases, and 3) the RF phase shifts at the array elements. This technique has several significant features. First, it involves the use of two auxiliary antennas. One is a remote continuous wave (CW) source directed at the phased-array antenna. The other is a passive antenna mounted close to the phased-array antenna. Its output is used to produce a reference phase for phase measurements. Second, it contains a technique to reduce the errors in phase estimates. Third, it takes note that beam steering uses phase sums of the form ( \phi_{k} + \beta _{kl} ), where \phi_{k} is the tuning phase for the k th array elemenet and \beta _{kl} , is an RF phase shift of the array element, and pays special attention to reduce the errors associated with the estimates of these sums. Fourth, it assumes the use of a reasonably stable and strong CW source of commerically available quality. No other assumptions are made. Experimental results obtained with a 295-element S -band space-fed phased-array antenna are given. View full abstract»

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  • Far-field accuracy investigation using modulated scattering technique for fast near-field measurements

    Publication Year: 1985 , Page(s): 279 - 285
    Cited by:  Papers (9)
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    Near field measurement techniques in conjunction with near-field to far-field transformation algorithms are widely used today. Two of the most important concerns are, firstly, the degree of accuracy achieved, and secondly, the measurement duration. Although high degrees of accuracy can be obtained, the time required to scan completely the near field of an antenna using the classical near-field measurement techniques is rather long. The modulated scattering technique would offer a means to reduce this time by a factor of 10 to 100 while maintaining a reasonable degree of accuracy. Using this technique, however, one introduces further sources of inaccuracy such as the mutual coupling between the elements of the array used to probe the test antenna, and the further limitation of the available measurement dynamic range. In this paper, these two sources of inaccuracy inherent in this technique or other techniques which use a similar set-up, are explored. Multiple reflections between the test antenna and the probe array are ignored. A parabolic reflector is chosen as the test antenna, and an array of dipoles is chosen as the probe antenna in the numerical simulation. View full abstract»

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  • Cross-correlation antenna systems with modified principal solution spatial frequency transfer functions

    Publication Year: 1985 , Page(s): 312 - 320
    Cited by:  Papers (5)
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    The principal solution type of spatial frequency transfer function (SFTF) for a linear antenna system, e.g., line source or linear array, is constant (flat) over its entire spatial frequency (SF) passband and drops abruptly to zero at the edges of the band. Such a SFTF is obtainable with cross-correlation (multiplicative) techniques. The associated power pattern, of the \sin (Lu)/Lu type, has high sidelobes diminishing asymptotically as u^{-1} . Moreover, the weighting distribution for the line source has an inverse taper with end point singularities. A modified principal solution SFTF, flat over most of the SF passband but with a smoothly varying transition function of the quadratic-linear-quadratic type at the edges of the passband is introduced. This engenders a power pattern whose sidelobes diminish asymptotically as u^{-3} instead of u^{-1} . The line source weighting distributions, moreover, are continuous and free of singularities, making physical realizability no longer a problem. View full abstract»

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  • On the amplitude center of radiating apertures

    Publication Year: 1985 , Page(s): 330 - 335
    Cited by:  Papers (7)
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    An explicit formula is derived for locating the amplitude center of planar apertures radiating scalar fields. Numerical examples are given which shows the validity of the formula for scalar conical and pyramidal horns. View full abstract»

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  • Modal behavior of spherical waves from a source of EM radiation with application to spherical scanning

    Publication Year: 1985 , Page(s): 350 - 354
    Cited by:  Papers (8)
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    An exact analysis for deriving closed-form expressions for the coefficients of free-space spherical modes radiated by typical linear, array, and aperture type of antennas is presented. This analysis is employed to determine the number of spherical modes required to reconstruct the near/ far fields (NF/FF) with a prescribed accuracy. The analysis developed together with the theory of probe-compensated spherical scanning is also employed to arrive at a criterion for the minimum distance of separation between the probe and test antenna which will enable accurate nonprobe corrected spherical scanning possible. View full abstract»

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  • Stratified refractivity effects on microwave propagation near the earth's surface

    Publication Year: 1985 , Page(s): 337 - 346
    Cited by:  Papers (1)
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    The effects on microwave radar performance of a horizontally stratified refractive index within the first 8 m of the earth's surface are considered. The radar propagation paths examined are near horizontal and about 1 km in length. The effects of several assumed refractivity profiles on the antenna pattern and on the interference produced by ground reflection are shown. Field test results compare the predicted radar performance obtained from a knowledge of the refractivity profile with the observed performance. View full abstract»

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  • Electric surface current model for the analysis of microstrip antennas with application to rectangular elements

    Publication Year: 1985 , Page(s): 301 - 311
    Cited by:  Papers (24)
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    An approach to the analysis of microstrip antennas which is applicable also to relatively thick substrates using the relevant Green's function is presented. The Green's function is derived and closed form expressions for various antenna characteristics which explicitly take into account the presence of the dielectric material are obtained in terms of the electric surface current density. For rectangular microstrip elements near resonance the current distribution is approximated using lossless transmission line analysis, thus enabling the complete evaluation of the characteristics of the element near resonance. The results obtained in this approach for the radiation resistance, surface wave resistance, radiation pattern, directivity, and bandwidth are presented in a detailed set of graphs for a representative set of parameters. View full abstract»

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  • Time harmonic solutions for a long horizontal wire over the ground with grazing incidence

    Publication Year: 1985 , Page(s): 233 - 243
    Cited by:  Papers (8)
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    A parametric study of the current responses on a long horizontal wire over the ground with frequencies ranging from 10 kHz to 100 MHz, earth conductivities of 10^{-1}, 10^{-2} , and 10^{-3} S/m, and wire heights of 10, 5, and 1 m. These current responses for typical wire lengths are given for a grazing incident plane wave and an incident lateral wave. View full abstract»

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Aims & Scope

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

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Editor-in-Chief                                                 Kwok W. Leung