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Antennas and Propagation, IEEE Transactions on

Issue 2 • Date March 1967

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Displaying Results 1 - 25 of 49
  • [Front cover and table of contents]

    Publication Year: 1967 , Page(s): 0
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    Freely Available from IEEE
  • A study of the sheath helix with a conducting core and its application to the helical antenna

    Publication Year: 1967 , Page(s): 203 - 210
    Cited by:  Papers (11)  |  Patents (1)
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    A theoretical study of the sheath helix antenna with a conducting core is made via the complex solutions of an associated determinantal equation. The variation of the characteristics of operation with respect to core size and pitch angle is established. A comparison of the complex solutions for the sheath helix and tape helix indicates that a good understanding of the helical antenna can be gained from the sheath model. In particular, explaining broadside radiation in terms of complex solutions is shown to give results in agreement with previously reported empirical data. However, this comparison also points out the limitations of the sheath model in predicting the operational parameters accurately. View full abstract»

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  • Gain measurements of vertically polarized antennas over imperfect ground

    Publication Year: 1967 , Page(s): 211 - 216
    Cited by:  Papers (12)
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    A technique is described for measuring the absolute gain of vertically polarized HF antennas. A horizontal half-wave dipole, located near the antenna being measured (test antenna), is used as a reference in a comparison type of gain measurement. A rotatable, linearly polarized, transmitting antenna is mounted on an airplane and used to illuminate the test-reference antenna location. With the airborne antenna vertical, the response of the test antenna is measured. The airborne antenna is quickly rotated to a horizontal position and the response of the reference dipole is measured. When the airplane is in the main lobe of the test and reference antennas, these two measurements yield the gain of the test antenna relative to that of the reference dipole. The gain of a horizontal half-wave dipole is presented graphically, versus main lobe elevation angle, for various heights above imperfect ground. Mutual impedance variations were considered in the computations for these graphs. Model antenna measurements were made at 400 MHz to verify the principle of the technique. On-site HF measurements could give gain figures accurate to within a few tenths of a dB of their true value. View full abstract»

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  • Discussion [Editor??s comment and Author's reply]

    Publication Year: 1967 , Page(s): 221
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    The Editor has brought to the author??s attention and would also like the readers to be aware that an alternate formulation of the above contours of relative polarization efficiency is possible. This results if orthographic instead of stereographic projection is used. In replying, the author notes that the stereographic projection has a number of advantages. View full abstract»

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  • Field of an axially circular cylinder clad with an inhomogeneous dielectric

    Publication Year: 1967 , Page(s): 222 - 226
    Cited by:  Papers (2)
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    This paper is concerned with the problem of an axial slot on a circular cylinder clad with a radially inhomogeneous dielectric of the form \epsilon(\rho)=(\rho/b)^{2p}, a \leq \rho \leq b , where a is the radius of the conducting cylinder, b is the outer radius of the dielectric coating, and p is an arbitrary parameter. The assumed profile is capable of representing an inhomogeneous cold plasma when p > 0 and a real dielectric when p < 0 . The apparent advantage of the present formulation is that the wave equation can be solved in terms of known functions and the solution can be extended to large cylinders. Field expressions appropriate to small and large cylinders are found using standard methods of harmonic series representation, Watson transformation, and saddle point integration. In the case of large cylinders coated with cold plasma, the radiation patterns are plotted for various combinations of the cylinder radius, thickness of the coating, and the inhomogeneity gradient. The radiation patterns are in good agreement with qualitative arguments of geometric optics. View full abstract»

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  • Aperture feed for a spherical reflector

    Publication Year: 1967 , Page(s): 227 - 230
    Cited by:  Papers (8)
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    The problem of designing a feed system for illuminating a spherical reflector is examined. A method is proposed for specifying the required field distribution over the aperture of the feed system, and the primary illumination and gain resulting from this distribution are derived. The results indicate that a significantly smaller feed aperture can be employed than would be indicated by conventional ray tracing methods. Specific numerical results are obtained by taking the Arecibo antenna as an example, for which a calculated aperture efficiency of 67.5 percent is possible with approximately a 38-foot-diameter aperture feed. View full abstract»

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  • An experiment on antenna arrays with randomly spaced elements

    Publication Year: 1967 , Page(s): 231 - 235
    Cited by:  Papers (11)
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    An experimental investigation on the planar array with randomly spaced elements was made by using the holey-plate technique. Two sample arrays, each consisting of 210 elements over a circular aperture of about 56 wavelengths in diameter, were tested at 71.25 GHz. The measured sidelobe levels were -12.8 dB and -13 dB, in excellent agreement with the theory which predicted below -12.8 dB with 90 percent probability and -13.3 dB with 50 percent probability. Further, one may consider the pattern in each plane cutting through the antenna as that of a linear random array. Thus one may study the sample distribution of the sidelobe levels of as many linear random arrays as cuts. The results showed a nearly perfect agreement with the theory, despite the fact that in the theory the mutual coupling effect was neglected altogether. This experiment seems to suggest that when the average element spacing is of the order of a few wavelengths or more, the net coupling effect on the pattern of a random array is generally negligible. View full abstract»

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  • Correction to "The grating-lobe series for the impedance variation in a planar phased-array antenna"

    Publication Year: 1967 , Page(s): 235
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  • Current distribution and input admittance of an infinite cylindrical antenna in anisotropic plasma

    Publication Year: 1967 , Page(s): 244 - 252
    Cited by:  Papers (8)
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    The current distribution and input admittance of an infinitely long cylindrical antenna driven by a slice generator and immersed in an anisotropic plasma are investigated. The applied dc magnetic field is along the axis of the antenna. By superimposing the characteristic waves guided along the antenna, the current solution is obtained in the form of a one-dimensional integral, which is examined both analytically and numerically. When K_{\perp } > 0 , the magnitude of the current decays slowly with the distance from the source, and its phase is nearly linear with a "propagation constant" equal to \sqrt {K_{\perp }}k_{0} for an antenna with very small radius. When K_{\perp } < 0 , the magnitude of the current decreases rapidly away from the source, and its phase is no longer linear. The input admittance decreases with the radius of the antenna. View full abstract»

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  • Coherent pulse transmission through rain

    Publication Year: 1967 , Page(s): 252 - 256
    Cited by:  Papers (5)
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    The problem of received signal degradation for coherent pulse transmission through a rain scattering volume was investigated for large bandwidth transmission at 4.0, 8.0, 15.5, and 34.86 GHz. Calculations of pulse length and total pulse energy were made for different path lengths through the rain volume. The calculations were made for models of heavy and extreme rainfall, using rain rates 49.0 and 196.3 mm/h. The results of the computations show that for the rain rates considered, the dominant cause of signal degradation is attenuation. Negligible pulse lengthening was noted at 34.86 GHz. For rain rates above 196 mm/h and frequencies of 15.5 and 8.0 GHz, measurable values of pulse lengthening were calculated for bandwidths above 2.0 GHz. At 4.0 GHz, measurable values of pulse lengthening were obtained for both rain rates considered. View full abstract»

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  • Propagation of an electromagnetic pulse from a nuclear burst

    Publication Year: 1967 , Page(s): 256 - 263
    Cited by:  Papers (1)
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    The general study of nuclear detection clearly identifies the theoretical problem of predicting the effect of the propagation medium on the form or shape of the low-frequency electromagnetic pulse of nuclear origin propagated to great distance in the terrestrial waveguide. This is accomplished with a theory of propagation into which an arbitrary electron density profile of the ionosphere can be introduced using a quite general cold magnetoplasma theory. In a previous paper by the author, the propagation of the ground wave electromagnetic pulse was discussed in detail and the engineering significance of the propagation theory, to nuclear detection systems was considered quantitatively. At distances from the source greater than approximately 100 km, the ionosphere reflections become an important consideration. The theory of propagation for ionospheric waves is introduced into the analysis in this paper. A transient waveform reconstructed theoretically at great distance from the source can be analyzed in the time domain with the aid of a geometric series expansion of the solution in the space domain. Thus, different times on the propagated pulse can be identified with particular reflection regions of the ground and ionosphere along the propagation path. In the geometric-optical limit, the individual ionospheric waves correspond approximately to rays traveling to and fro between the ionosphere and the ground, and the composite pulse at great distance can be considered to be a superposition of a multiplicity of pulses, each pulse delayed in time by the delay time of the ray. View full abstract»

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  • Short-term and averaged characteristics of nonreciprocal HF ionospheric paths

    Publication Year: 1967 , Page(s): 268 - 277
    Cited by:  Papers (2)
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    This paper reports an investigation into the ability of ray theory to explain nonreciprocity on HF ionospheric paths. It first reviews and extends some of the predictions of the ray theory of reciprocity as applied to single and multi-hop propagation paths. In this, ray theory predicts nonreciprocity in phase for single magnetoionic waves transmitted between horizontally polarized antennas. If the antennas are elliptically polarized, there can also be nonreciprocity in amplitudes. It is shown that experimental observations on several circuits using linearly polarized antennas support the validity of predictions based on ray theory. In particular: 1) the correlation between two-way, short-term fading of pulsed signals was positive and high when only one magnetoionic wave was present in the signal, but negative or low when both ordinary and extraordinary waves were present 2) the six-minute averaged path loss in opposite directions was equal within experimental errors for signals that underwent polarization fading. Short-term discrepancies were found and these can be attributed to insufficient averaging of polarization fading effects. Systematic differences in the path loss in opposite directions observed by others could be explained if the antennas were elliptically polarized for transmission paths that deviated from the great-circle path. View full abstract»

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  • Complex-correlation radiometer

    Publication Year: 1967 , Page(s): 286 - 290
    Cited by:  Papers (1)
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    The correlation between the signals from the two antennas in a radio interferometer can be described by a complex correlation function. The real and imaginary parts of this function can be measured by a radiometer using two feedback loops to control four noise sources, B_{pr} (positive, real), B_{nr} (negative, real), B_{\pi} (positive, imaginary), and B_{\ni} (negative, imaginary). Theoretical analysis shows the system to be stable against amplifier gain fluctuations, and against moderate fluctuations in the phase shifts of the two amplification channels which are included in the system. Experimental verification is described in a following paper by Hubbard and Erickson [2]. View full abstract»

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  • A stabilized cross-correlation radiometer

    Publication Year: 1967 , Page(s): 291 - 294
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    A new type of correlation radiometer has been built for use at decametric wavelengths by the University of Maryland's Clark Lake Radio Observatory, Borrego, Calif. The primary function of this system is to cross-correlate the signals between two sections of the Clark Lake array. The correlated signals are measured by a receiver using two feedback loops which control four noise diodes. Each feedback loop is similar to a Ryle-Vonberg receiver. The system is insensitive to amplifier gain changes, and to small changes in relative phase shift between amplifiers. An additional advantage for radio astronomy is that a linear power response is obtained, regardless of the receiver detector law. View full abstract»

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  • Independent angular steering of each zero of the directional pattern for a linear array

    Publication Year: 1967 , Page(s): 296 - 298
    Cited by:  Papers (32)  |  Patents (1)
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  • Maximum power transfer between finite antennas

    Publication Year: 1967 , Page(s): 298 - 300
    Cited by:  Papers (5)
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    The optimum illumination for maximum power transfer between two opposed rotationally symmetric antennas is determined. The antennas have spherical surfaces and dissimilar apertures. Given an angular variation of the illumination of \cos (\alpha \theta) , with \alpha integral, the optimum radial distribution becomes solutions of a finite Hankel transform. View full abstract»

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  • Wide band phase shifters

    Publication Year: 1967 , Page(s): 300
    Cited by:  Papers (6)
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    Latching ferrite phase shifters, in waveguide, with digital control have been used in the past and have, in particular, found application in phased arrays. The devices are capable of extremely wide bandwidth. The authors present the configuration of a phase shifter constructed with Trans Tech TT1-109 ferrite. It consists of four digital bits giving differential phase shifts of nominally 180, 90, 45 and 22.5 degrees. The wide band response is given and shows the performance of the 180-degree bit. Also shown is the insertion loss of a complete phase shifter with four bits. All measurements were carried out with the ferrite in a state of magnetic remanence obtained from a current pulse of 4 A. The useful range of the phase shifter is seen to extend from the upper edge of S band through X band. View full abstract»

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  • On the transient response of an infinite cylindrical antenna

    Publication Year: 1967 , Page(s): 301 - 302
    Cited by:  Papers (17)
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  • Optimum relative dimension of permeable cores

    Publication Year: 1967 , Page(s): 305 - 307
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  • Dual mode small-aperture antennas

    Publication Year: 1967 , Page(s): 307 - 308
    Cited by:  Papers (12)  |  Patents (1)
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  • Propagation constants of leaky-wave antenna for near end-fire radiation

    Publication Year: 1967 , Page(s): 308 - 309
    Cited by:  Papers (1)
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  • Gain computations from pattern integration

    Publication Year: 1967 , Page(s): 309 - 311
    Cited by:  Papers (4)
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    Moving an antenna with respect to the center of rotation of an antenna rotator will change experimental recorded patterns. A theoretical correction for this situation is derived for gain computations based on pattern integration. Use of the correction factor enables an experimentor to obtain several semi-independent measurements of gain. View full abstract»

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  • Lunar range radiation patterns of a 210-foot antenna at S-band

    Publication Year: 1967 , Page(s): 311 - 313
    Cited by:  Papers (1)
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  • Active impedance of a phased-array antenna element simulated by a single element in waveguide

    Publication Year: 1967 , Page(s): 313 - 314
    Cited by:  Papers (5)
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  • Systematic design of a matrix network used for antenna beam steering

    Publication Year: 1967 , Page(s): 314 - 316
    Cited by:  Papers (4)
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Aims & Scope

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

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Meet Our Editors

Editor-in-Chief                                                 Kwok W. Leung