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Antennas and Propagation, IEEE Transactions on

Issue 4 • Date July 1970

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  • [Front cover and table of contents]

    Publication Year: 1970 , Page(s): 0
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    Freely Available from IEEE
  • Preface

    Publication Year: 1970 , Page(s): 446
    Cited by:  Papers (1)
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    Freely Available from IEEE
  • [Back cover]

    Publication Year: 1970 , Page(s): c4
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    Freely Available from IEEE
  • The design of radially symmetric lenses

    Publication Year: 1970 , Page(s): 497 - 506
    Cited by:  Papers (13)  |  Patents (3)
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    For scanning over wide angles at millimeter wavelengths, an antenna incorporating a radially symmetric lens is an attractive solution if the lens can be realized in a practical form. It is shown that suitable lenses can be constructed very simply, from natural dielectrics if desired, and a design technique for the optimal antenna is presented. Some results are given of analytical and experimental studies of a number of actual antennas operating at wavelengths near 4 mm. These confirm that practical solutions are available. Homogeneous lenses may be used up to antenna gains of about 35 dB, and a lens consisting of a single shell and a core is sufficient for most other practical requirements. View full abstract»

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  • Atmospheric absorption of radio waves between 150 and 350 GHz

    Publication Year: 1970 , Page(s): 479 - 485
    Cited by:  Papers (4)
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    This paper compares several forms for the absorption line shapes for atmospheric gases as applied to frequencies between 150 and 350 GHz. The contributions of various lines to the absorption in this frequency range are examined. Equations are presented for direct calculation of attenuation as a function of pressure, temperature, and water vapor density. View full abstract»

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  • Radio propagation at 27-40 GHz

    Publication Year: 1970 , Page(s): 452 - 462
    Cited by:  Papers (3)
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    A test program has been carried out in the greater Washington, D. C., area to investigate the feasibility of wide-band transmission at millimeter wavelengths. Measurements were made between July, 1967, and February, 1968, over an 8-km path and between March and August, 1968, over a 32-km path. Experimental determinations of the parameters significant in the design and assessment of the capability of communications systems propagating in the 27-40-GHz frequency band were made. A description of the program, summary of the radio and meteorological data, and conclusions relevant to the transmission over both paths, are presented. View full abstract»

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  • Effect of finite ground plane conductivity on aperture admittance

    Publication Year: 1970 , Page(s): 565 - 566
    Cited by:  Papers (1)
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    An upper bound on the error involved in approximating the actual admittance of an aperture in an imperfectly conducting ground plane by the admittance of the same aperture located in a perfectly conducting plane is obtained. View full abstract»

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  • Remote probing of atmosphere and wind velocity by millimeter waves

    Publication Year: 1970 , Page(s): 493 - 497
    Cited by:  Papers (4)
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    A technique is developed to probe the atmospheric turbulence strength C_{n}^{2} and the wind velocity along a path using millimeter waves as a tool. Data obtained in a line-of-sight millimeter-wave propagation experiment are processed and used as the source of information. The averaged C_{n}^{2} and wind velocity together with their gradients along the propagation path are calculated by inverting a set of integral equations. A numerical method is used to yield the least-square-error solutions. Comparison is made between the theoretically calculated wind velocity over a 33-hour period and that measured by a conventional anemometer. View full abstract»

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  • A technique for obtaining the Doppler spectrum for sampled amplitude-phase data in a data-gathering array

    Publication Year: 1970 , Page(s): 580 - 582
    Cited by:  Papers (1)
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    A technique developed to obtain the Doppler frequency spectrum as a function of the angle of arrival for a received signal from sampled amplitude and phase information, taken with a data-gathering receiving array, is described. View full abstract»

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  • Pattern distortion due to edge diffractions

    Publication Year: 1970 , Page(s): 561 - 563
    Cited by:  Papers (17)
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    The method of combining wedge diffraction solutions for the analysis of an axial TEM-mode slot is extended here for an arbitrary aperture antenna in a finite size ground plane. The new approach, however, considers superposition of boundary-value and wedge-diffraction solutions on the same antenna. The boundary-value solution (primary pattern) considers the pattern component when the aperture is in an infinite ground plane, and the diffraction solution (secondary pattern) considers the contribution to the pattern from the edges of the finite ground plane. View full abstract»

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  • Attenuation and emission of the atmosphere at 3.3 mm

    Publication Year: 1970 , Page(s): 485 - 490
    Cited by:  Papers (6)
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    Four empirical relationships are presented between the 3.3-mm attenuation determined from observations of the sun and 1) radiosonde measurements of the total amount of precipitable water in the atmosphere, 2) surface measurements of absolute humidity, 3) IR spectral hygrometer observations of the sun, and 4) observations of differential atmospheric emission at 3.3 mm. Fluctuations in atmospheric emission at 3.3 mm during good weather do not put any limit on the sensitivity of a dual-beam observing system using a receiver whose rms noise fluctuations in an output bandwidth of 0.25 Hz are \approx 0.5\deg K. View full abstract»

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  • Measurements of surface currents on a finite circular tube illuminated by electromagnetic wave

    Publication Year: 1970 , Page(s): 569 - 573
    Cited by:  Papers (4)
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    An experiment is designed to confirm a rigorous theory on the three-dimensional electromagnetic scattering from a circular tube of finite length. Both axial and transverse components of the outside total current for the case of E polarization have been measured for two finite tubes with ka = 1.895 and kh = 0.4827\pi and 0.724\pi , both as a function of z or \theta . Special care was taken to preserve the continuity of the transverse current after each change in the position of the probe. The measured results are in good agreement with the theoretically computed data. Theoretical curves for the corresponding infinite cylinder are also included to show the limitations of using them as approximations to the currents on finite cylinders. View full abstract»

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  • The influence of heavy rainfall on attenuation at 18.5 and 30.9 GHz

    Publication Year: 1970 , Page(s): 507 - 511
    Cited by:  Papers (6)
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    Percent-of-time distributions of rain-induced fades obtained on a 6.4-km path in New Jersey operating at a frequency of 18.5 GHz are discussed for the period of 1968-1969; data obtained at 30.9 GHz on a 1.9-km path for the same period are also discussed. The attenuation distributions are compared with attenuations calculated from the distributions of average rain rates on the paths. With these data, it is found that distributions of attenuation can be predicted from the path-average rain-rate distributions for a given sample period. Detailed rain-rate and attenuation measurements at 18.5 GHz on the 6.4-km path are presented for the most intense storm observed in a three year recording period. Point rain rates in excess of 250 mm/h and path-average rates exceeding 180 mm/h were observed; the attenuation exceeded the 50-dB dynamic measuring range of the equipment for more than seven minutes. View full abstract»

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  • Some properties of the gain of uniform and nonuniform arrays

    Publication Year: 1970 , Page(s): 556 - 558
    Cited by:  Papers (3)
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    Some characteristics of the directivity function of uniformly spaced and nonuniformly spaced arrays are presented. In particular, the lower bound of the directivity function and the asymptotic expansion for the directivity of some composite arrays are examined. View full abstract»

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  • Millimeter wave propagation measurements from the applications technology satellite (ATS-V)

    Publication Year: 1970 , Page(s): 535 - 552
    Cited by:  Papers (5)
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    A millimeter wave propagation experiment was launched on-board the Applications Technology Satellite (ATSV) in August, 1969, and is providing the first information on the propagation characteristics of the earth's atmosphere for earth-space links in the K_{u} (12.5 to 18 GHz) and K_{a} (26.5 to 40 GHz) frequency bands. Seven participating stations commenced data acquisition operations early in October, 1969. Amplitude and phase measurements on two independent test links at 15.3 GHz (downlink) and 31.65 GHz (uplink) are providing propagation characteristics during defined weather conditions. These measurements will provide the systems designer with a data base to support performance predictions for projected millimeter wave links and will aid in determining the utility of these frequency bands for communications and data-link applications. The satellite did not achieve the 3-axis earth-oriented stabilization condition that was originally planned and is presently spinning at 76 r/min at 105\deg west longitude, in geosynchronous orbit. Modifications have been made to the existing data analysis program which permit the conduct of meaningful propagation measurements, even with spin modulated data. Spacecraft and ground hardware systems are described, including modifications required by the satellite spin. Preliminary measurements acquired at the NASA Rosman, N. C. station during the early months of satellite operation are presented, including comparisons of attenuation with rainfall rate, sky temperature, and weather classification observations. The data available to date (March, 1970) are not yet sufficient to fully describe the long-term propagation statistics over all expected weather conditions, but they are presented here in response to requests for information on the initial characteristics of the first experimental data available from an operational earth-space millimeter wave link. View full abstract»

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  • Element spacing limitations of Dolph-Pritchard optimum endfire arrays

    Publication Year: 1970 , Page(s): 563 - 564
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    It is generally accepted that the Dolph-Pritchard technique for computing optimum or Chebyshev radiation patterns for single-lobe endfire arrays is valid for any array element spacing less than one-half wavelength. However, it can be shown that multiple-lobe radiation patterns will be obtained using this technique for element spacing less than one-half wavelength. A maximum element spacing for single-lobe radiation patterns can be derived, and this spacing is a function of the major-lobe-to-sidelobe amplitude ratio as well as the order of the Chebyshev polynomial. In general, for large amplitude ratios this maximum spacing approaches one-quarter wavelength. View full abstract»

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  • Effects of dielectrics on the radiation patterns of an electromagnetic horn

    Publication Year: 1970 , Page(s): 553 - 556
    Cited by:  Papers (1)  |  Patents (2)
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    Experimental results of the effects of dielectrics on the radiation pattern of electromagnetic horns are presented. The experiments were conducted with triangular and modified triangular shapes of dielectric materials. Because of the ease of fabrication, styrofoam was chosen for the dielectric. Furthermore, the low dielectric constant ( \epsilon_{r} = 1.03 ) of this material reduces the signal reflections at the air-dielectric interface. The dielectric was placed inside a 7-foot long E -plane sectoral horn operating at X -band frequencies. Near- and far-field measurements showed that the dielectric, in spite of its low dielectric constant, changed the phase and the power distribution across the aperture of the horn. By judicious choice of the shape and material of the dielectric, an antenna beam with sidelobes below -40 dB can be obtained. View full abstract»

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  • Propagation of centimeter and millimeter wavelengths through precipitation

    Publication Year: 1970 , Page(s): 530 - 534
    Cited by:  Papers (4)
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    From theoretical considerations, it is possible to calculate attenuation through rain at several wavelengths. It is shown that attenuation is a linear function of rain rate for a 0.86- cm wavelength. This property is independent of the distribution spectra of drop radius within a ten-percent precision. This later property has been tested experimentally in two different ways. 1) Measurements through rain have been made with a radar at 0.86 cm. Results are reported. They show quite important differences between theoretical and experimental results. 2) Experiments have been conducted in rainfall to measure fall speeds and diameter spectra of drops. The apparatus used for this purpose is briefly described. With the results obtained it is possible to calculate the propagation properties of rainfall at several wavelengths, particularly at 0.86 cm. We hope to be able to compare the results obtained with those observed by radar in the future. The interest in short wavelengths for radiolocation or radio communication is well known, but when using shorter wavelengths we encounter greater attenuation in the atmosphere. We know that for wavelengths between 1 and 10 cm, attenuation by atmospheric gases may be neglected (except near 1.25 cm). At millimetric wavelengths, propagation is only possible in certain bands. At 0.86 cm, attenuation by oxygen and water vapor is not negligible, but can be considered constant. At the wavelengths of 0.4 cm and 0.20 cm, attenuation is dependent upon the concentration of water vapor, that is to says upon meteorological conditions. The effect of atmospheric particles is more important with shorter wavelengths. Practically negligible at 10 cm, attenuation by precipitation begins to be important at 3 cm and 5.5 cm and is strong at 0.86 cm and other milllmetric wavelengths. The purpose of the present work is to study theoretically effects of rainfall at several wavelengths. View full abstract»

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  • Astronomical refraction at millimeter wavelengths

    Publication Year: 1970 , Page(s): 490 - 493
    Cited by:  Papers (2)
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    Measurements of the difference between radio and optical astronomical refraction at \lambda =8.6, 4.3, 3.1 , and 2.2 mm are described. The measurement technique utilized solar limb crossing times observed with a 16-foot radio telescope. Results show the expected dependence upon atmospheric water vapor below \lambda = 3 mm, but radio refraction tends to approach optical refraction at the shortest wavelength. View full abstract»

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  • Scattering of electromagnetic waves from a layer with rough front and plane back (small perturbation method by Rice)

    Publication Year: 1970 , Page(s): 573 - 576
    Cited by:  Papers (6)
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    Rice's small perturbation method is extended to obtain first- and second-order terms of the field scattered from a rough layer. The first-order terms are utilized to obtain average scattering cross sections. Lossy and lossless layers are considered for horizontal and vertical polarizations. View full abstract»

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  • Comparison of simultaneous line-of-sight signals at 9.6 and 34.5 GHz

    Publication Year: 1970 , Page(s): 447 - 451
    Cited by:  Papers (9)
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    Signals at 9.6 and 34.52 GHz, propagated simultaneously over a slant line-of-sight overwater path, have been analyzed to compare the power spectra of phase-of-arrival variations and fading and to determine the coherence of these signals with regard to both phase variations and fading. The phase data at the two radio frequencies exhibited nearly identical power spectra from 0.01 to 5 Hz and very high coherence from 0.01 to 0.1 Hz. The coherence dropped rapidly above 0.1 Hz and was in most cases less than 0.4 above 0.5 Hz. The power spectra of fading were similar in shape at the two frequencies, but the fading spectral density was consistently higher at 34.52 GHz than at 9.6 GHz from 0.1 to 5 Hz. The shape of the coherence function for fading was similar to that of the corresponding phase coherence function, but the fading coherence was lower at the low spectral frequencies. The possible effect of the small spatial separation of the propagation path on the coherence analysis is discussed. View full abstract»

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  • Design, development, and initial measurements of a 1.4-mm radiometric system

    Publication Year: 1970 , Page(s): 512 - 514
    Cited by:  Papers (4)
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    The development of a 1.4-mm heterodyne radiometric system and the initial measurements taken with it are described. The \Delta T of the system at the antenna terminals was approximately 18.5\deg K for a 0.25-Hz post-correlation noise bandwidth. Measurements show that the attenuation through the atmosphere at this wavelength is primarily due to water vapor, and an estimate of the zenith attenuation is given by A (dB)= 2.8w , where w is the precipitable water in centimeters. Measurements of the antenna half-power beamwidths using the sun as a source show that at 1.4 mm the atmospheric turbulence effects are not appreciable for observations through the atmosphere at zenith angles less than 45\deg with a 15-foot antenna. View full abstract»

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  • Comparison of some correlation array configurations for radio astronomy

    Publication Year: 1970 , Page(s): 567 - 569
    Cited by:  Papers (1)
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    The number of nonredundant baselines obtained from the T, Y, and ring array configurations are compared. For the same number of array elements, it is shown that the ring array has the largest number of baselines. The Y array has the second largest number of baselines; however, it also has more potential for adjustments and future growth. View full abstract»

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  • High resolution millimeter reflector antennas

    Publication Year: 1970 , Page(s): 515 - 529
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1960 KB)  

    The foremost millimeter reflector antennas in use are surveyed. Antenna descriptions are written by personnel at the institutions operating the antennas. The antennas described are the following: 1) MIT 28-foot and 120-foot (U.S.A.), 2) Lebedev and Crimean RT 22-meter (USSR), 3) Aerospace 15-foot (U.S.A.), 4) University of Texas 16-foot (U.S.A.), 5) AFCRL 29-foot (U.S.A.), 6) Bonn University 10-meter (Germany), 7) (CRC (DRTE) 30-foot (Canada), 8) NRAO 36-foot (U.S.A.), 9) Berkeley 20-foot (U.S.A.), and 10) JPL 18-4oot (U.S.A.). Antenna system descriptions include information on antenna performance, pointing capabilities, limitations, and principal applications. The antennas are used in radio astronomy and communication research. The reference section covers the major results obtained with the antennas. View full abstract»

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  • Short cylindrical antennas with enhanced radiation or high directivity

    Publication Year: 1970 , Page(s): 576 - 580
    Cited by:  Papers (5)
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    The feasibility of enhancing the radiated power or improving the directivity of a short cylindrical antenna by double impedance loading is investigated. An approximate solution for the current on a doubly loaded short antenna is developed, and typical current dlstributions, impedances, and radiation patterns of antennas appropriately loaded to implement enhanced radiation or high directivity are presented. Significant improvements in radiated power or directivity can be achieved with optimum impedance loadings. Theoretical predictions are verified by the results of an experimental study. 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