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IEE Proceedings - Microwaves, Antennas and Propagation

Issue 5 • Oct. 1994

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Displaying Results 1 - 16 of 16
  • Design and performance of a perforated dielectric Fresnel lens

    Publication Year: 1994
    Cited by:  Papers (28)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (371 KB)

    A phase-compensating Fresnel lens using a perforated dielectric material has been designed and fabricated. The perforations in the dielectric material are designed to create the zones of different dielectric constants needed to obtain proper phase compensation in a Fresnel lens. A prototype lens designed to operate at 30 GHz was fabricated, and consisted of zones with four different synthesised va... View full abstract»

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  • Use of radiometers in atmospheric attenuation measurements

    Publication Year: 1994, Page(s):428 - 432
    Cited by:  Papers (6)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (364 KB)

    Measurements from radiometers operating at 20 and 30 GHz were used to predict attenuation along the 14° elevation angle from Blacksburg, Virginia, toward the Olympus satellite. Both NOAA Dicke switched radiometers and Virginia Tech total power radiometers collected data in Blacksburg for two months. The radiometrically predicted attenuation for the total power radiometers agreed well with that... View full abstract»

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  • Experimental evaluation of junction circulators: a review

    Publication Year: 1994, Page(s):351 - 358
    Cited by:  Papers (4)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (384 KB)

    The adjustment of any microwave device should always reflect as far as possible its physical properties. The purpose of the paper is to summarise existing experimental techniques for the characterisation of the classic 3-port junction circulator for which the inphase eigennetwork may be approximately represented by an electric wall boundary condition. Some important possibilities include its matri... View full abstract»

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  • Novel method of calculating the characteristic impedance of a coaxial transmission line of arbitrary cross-section

    Publication Year: 1994, Page(s):423 - 427
    Cited by:  Papers (2)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (260 KB)

    The paper presents a complete new method of calculating the characteristic impedance of a coaxial transmission line of arbitrary cross-section, by assuming that the characteristic impedance is a function of its areas and perimeters. An algebraic formula is found relating this impedance to the areas and the perimeters. Then the determination of the impedance of an arbitrary coaxial transmission lin... View full abstract»

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  • Active antenna top-cover frequency pulling effects

    Publication Year: 1994, Page(s):374 - 376
    Cited by:  Papers (2)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (224 KB)

    Active antenna load pulling effects are analysed in the presence of a partially reflecting superstrate (dielectric cover). The analytical and experimental results obtained exhibit distortion in the frequency pulling pattern of the active antenna. The results obtained can be used to design optimum cover placement or to postmanufacture tune the frequency of the active antenna module View full abstract»

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  • Integral equations for EM scattering by homogeneous/inhomogeneous two-dimensional chiral bodies

    Publication Year: 1994, Page(s):385 - 392
    Cited by:  Papers (3)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (464 KB)

    Two sets of integral equations are obtained for electromagnetic (EM) scattering by isotropic two-dimensional chiral bodies embedded in free space which can be attached to a perfect electric conducting (PEC) body. For the special case of homogeneous chiral media, integral equations (IEL) are obtained in terms of only line integrals involving the free-space and chiral media Green's functions. For th... View full abstract»

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  • Resonant frequencies and Q-factors of a spherical cavity loaded by an eccentric dielectric sphere

    Publication Year: 1994, Page(s):342 - 350
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (400 KB)

    A rigorous analysis for both resonant frequency and the Q-factor of the intrinsic modes in a spherical cavity loaded by an eccentric dielectric sphere is proposed. For generality, the outer shell of the structure is considered to be an arbitrary physical medium, e.g. a conductor of large but finite conductivity or a dielectric of high permittivity. With a rigorous representation for the field of t... View full abstract»

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  • Theoretical analysis of VHF-UHF propagation through air-vegetation-ground media

    Publication Year: 1994, Page(s):415 - 422
    Cited by:  Papers (1)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (384 KB)

    The electromagnetic radiation from a vertical electric dipole in three electrically different layers: air, vegetation and the ground is analysed. Starting with Maxwell's field equations, a rigorous analysis of the electromagnetic fields is carried out and an integral representation of the field components in the problem with two semi-infinite media is obtained. Using Debye's steepest descent metho... View full abstract»

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  • Full characterisation of varactor-loaded, probe-fed, rectangular, microstrip patch antennas

    Publication Year: 1994, Page(s):367 - 373
    Cited by:  Papers (17)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (460 KB)

    A thorough investigation of the radiation characteristics of a probe-fed microstrip patch loaded with a varactor diode is presented. The theoretical analysis used to model this structure incorporates the full-wave spectral domain integral technique in conjunction with an equivalent circuit model of the varactor diode. Attachment modes are used to accurately model the current through the feed and l... View full abstract»

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  • Transition zone diffraction by multiple edges

    Publication Year: 1994, Page(s):382 - 384
    Cited by:  Papers (8)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (184 KB)

    In UHF radio wave propagation over multiple buildings or hills, obstacles are often in the transition region near the shadow boundary where ray descriptions fail. It is shown that proper inclusion of slope diffraction within the UTD (uniform theory of diffraction) gives a good approximate solution, allowing a ray description in these cases. Comparison is made with a known solution for a few edges,... View full abstract»

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  • Contributions towards the development of a UTD-based model for cellular radio propagation prediction

    Publication Year: 1994, Page(s):407 - 414
    Cited by:  Papers (21)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (564 KB)

    The performance of a UTD-based model for path loss prediction in cellular radio systems is investigated. The model's performance is shown to compare favourably with physical optics based techniques, and to accurately predict the dependency of path loss on both path length and base station antenna height within certain bounds. The bounds of applicability reported show that such a model could find a... View full abstract»

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  • Analysis of radiation from active microstrip antennas

    Publication Year: 1994, Page(s):359 - 366
    Cited by:  Papers (5)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (428 KB)

    The current interest in active microstrip antennas has highlighted the need for analysis of the radiation characteristics of such antennas. The paper describes the extension of the small magnetic dipole source analysis of microstrip line discontinuities to active devices. The analysis is then combined with the patch cavity model to form a flexible, approximate analysis suitable for implementation ... View full abstract»

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  • Moment method solution of aperture-coupled hemispherical dielectric resonator antenna using exact modal Green's function

    Publication Year: 1994, Page(s):377 - 381
    Cited by:  Papers (2)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (268 KB)

    An aperture-coupled hemispherical dielectric resonator (DR) antenna excited at the end-fire TE221 mode has been studied. The exact magnetic-field Green's function of the DR antenna is presented, and the moment method is used to solve the equivalent current in the slot. From the magnetic current, the return loss of the antenna configuration is evaluated. The results are compared with the... View full abstract»

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  • Extended effective output noise temperatures of multiresponse systems

    Publication Year: 1994, Page(s):393 - 396
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (232 KB)

    The paper proposes a definition of an extended effective output noise temperature of single and multiresponse (linear and nonlinear) systems. Using an equivalent output noise temperature the confusion of different input noise temperature representations, e.g. SSB and DSB noise temperatures, is avoided. Also, the sign of the extended effective output noise temperature is the same as the sign of the... View full abstract»

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  • Modelling and measurements of the diffraction of microwaves by buildings

    Publication Year: 1994, Page(s):397 - 401
    Cited by:  Papers (7)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (380 KB)

    The growth of urban microwave systems has led to an increase in the probability of mutual interference between users of the same frequency band. A building which obstructs the interference path will generally lead to a reduction in the strength of the interfering signal. A method is presented whereby the amount of site shielding afforded by a rectangular building may be predicted, considering two-... View full abstract»

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  • Frequency dependent transmission line loss in quasitransversal microwave filters

    Publication Year: 1994, Page(s):402 - 406
    Cited by:  Papers (8)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (316 KB)

    A previously proposed synthesis procedure allows filters with almost arbitrary phase and amplitude responses to be designed as delay-line filters. Multiple reflections within the delay line are efficiently allowed for using a time-domain algorithm. The procedure has now been improved to allow for inherent frequency-dependent loss and dispersion in the transmission line. This overcomes a significan... View full abstract»

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IET Microwaves, Antennas & Propagation is dedicated to coverage of microwave and RF circuits; microwave and millimetre wave amplifiers; oscillators, switches, mixers and other components.

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