Browsing by Subject "Transmission line theory"

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    Estimation of Spurious Radiation from Microstrip Etches Using Closed-Form Green’s Functions
    (IEEE, 1992) Aksun, M.I.; Mittra, R.
    The problem of spurious radiation from electronic packages is considered in this paper by investigating the power radiated from microstrip etches that are excited by arbitrarily-located current sources, and terminated by complex loads at both ends. The first step in the procedure is to compute the current distribution on the microstrip line by using the method of moments (MoM). Two novel contributions of this paper are: (i) employing the recently-derived closed-form Green’s functions in the spatial domain that permit an efficient computation of the elements of the MoM matrix; (ii) incorporating complex load terminations in a convenient manner with virtually no increase in the computation time. The computed current distribution is subsequently used to calculate the spurious radiated power and the result is compared with that derived by using an approximate, transmission line analysis. © 1992 IEEE
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    Miniaturization and characterization of metamaterial resonant particles
    (IEEE, 2008-10) Aznar, F.; Bonache, J.; Martín, F.; Özbay, Ekmel; Alıcı, K. Boratay; Bilotti, F.; Tricarico, S.; Vegni, L.; Baena, J. D.; Jelinek, L.; Marqués, R.
    This paper is focussed on the miniaturization and characterization of semi-lumped resonators, of interest for the synthesis of metamaterial-based structures such as metamaterial transmission lines, frequency selective surfaces, absorbers, and radiating elements, among others. The particles consist on metallic patterns etched on a dielectric and are inspired on the split ring resonator, SRR (that is, the formerly resonant particle used for the synthesis of left handed metamaterials). The different strategies for miniaturization are discussed and examples are given. It is shown that by using two metallic levels connected through vias it is possible to achieve very small electrical size for the particles (namely, below λ/100, where λ is the wavelength in the considered substrate at resonance). A method to determine the electrical parameters of the resonators in metamaterial transmission line configurations is also presented, and the possibility to determine the characteristics of the isolated particles is discussed. Finally, examples of application of this technique are presented. This work is of interest for the synthesis of effective media metamaterials based on resonant elements. © 2008 EuMA.
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    Temperature-dependence of a GaN-based HEMT monolithic X-band low noise amplifier
    (IEEE, 2004-10) Schwindt, R. S.; Kumar, V.; Aktaş, Ozan; Lee, J.-W.; Adesida, I.
    The temperature-dependent performance of a fully monolithic AlGaN/GaN HEMT-based X-band low noise amplifier is reported. The circuit demonstrated a noise figure of 3.5 dB, gain of 7.5 dB, input return loss of -7.5 dB, and output return loss of -15 dB at 8.5 GHz at room temperature. The noise figure at 9.5 GHz increased from 2.5 dB at 43°C to 5.0 dB at 150°C. © 2004 IEEE.