• Effect of feedback carrier excitation on LED external quantum efficiency 

      Autor: Kučera, L.; Macháč, J.; Míšek, J.
      (IEEE, 1982-02)
      Self-absorption of photons generated by prior luminescence processes affects both the steady-state and transient characteristics of LEDs. In this study we confine ourselves to one of the most important steadystate ...
    • Static model of DH laser 

      Autor: Macháč, J.
      (IEEE, 1983-04)
      A method of complex analysis of the double-heterostructure stripe-geometry laser, based on a new static model, is presented. The optical field distribution in the active region of the laser is described by the wave equation. ...
    • Analysis of discontinuities in waveguiding structures by MAB method 

      Autor: Macháč, J.
      (IEEE, 1992-08)
      The method of minimal autonomous blocks (MAB) is briefly described. A universal code computing reflectivity and transmissivity of discontinuities in waveguide structures was developed on the basis of the MAB method. This ...
    • On the design of waveguide-to-microstrip and waveguide-to-coplanar line transitions 

      Autor: Macháč, Jan; Menzel, Wolfgang
      (IEEE, 1993-09)
      New versions of the waveguide-to-microstrip and waveguide-to-coplanar line transitions are described and analyzed. The transitions differ from the standard ones by a probe in the shape of a rectangular patch. The structure ...
    • Waveguide bandpass filters with attenuation of higher-order passbands 

      Autor: Menzel, Wolfgang; Macháč, Jan
      (IEEE, 1993-09)
      A new method is proposed to provide additional attenuation to higher-order passbands of metal waveguide bandpass filters. To this end, shunt waveguide sections with cut-off frequencies are included into the filter structure. ...
    • Short and Open Circuited Slot Line 

      Autor: Macháč, Jan; Zehentner, Ján; Menzel, Wolfgang
      (IEEE, 1995-07)
      A slot line terminated by the short and open end is analysed by the spectral domain method (SDM). The original process of Yang and Alexopoulos (1988) is modified by application of the piecewise sinusoidal functions only. ...
    • Load Impedances of Complex Slotline Terminations 

      Autor: Macháč, J.; Zehentner, J.; Menzel, W.
      (IEEE, 1995-09)
      Single slotline has gained new interest due to application in uniplanar circuits, antennas or active radiators, all these including slotline short circuits or even more complex terminations. This paper gives a new approach ...
    • Leakage Effects of Dominant and Higher Order Modes on Slotline 

      Autor: Macháč, Jan; Zehentner, Jan
      (IEEE, 1996-09)
      The properties of the slotline when the dominant bound or leaky wave propagates, together with the behaviour of new higher order modes are investigated. The frequency range in which the slotline transmits the bound wave ...
    • Upper Cut-Off Frequency of the Bound Wave and New Leaky Wave on the Slotline 

      Autor: Zehentner, Ján; Macháč, Jan; Migliozzi, Maurizio
      (IEEE, 1997-06)
      This paper contributes to a more profound understanding of uniplanar circuit behaviour. A simple closed-form formula providing the upper cut-off frequency of the bound wave propagating over the slotline is presented. A new ...
    • Evolution of New Real and Complex Improper Solutions of the Slotline Dispersion Equation 

      Autor: Zehentner, J.; Macháč, J.; Migliozzi, M.
      (IEEE, 1997-09)
      An attempt is made in this paper to reach a better understanding of the behaviour of open uniplanar circuits, particularly the slotline. A new second leaky wave has been revealed in addition to the dominant bound and leaky ...
    • Performance of the slotline in the mm-wave range 

      Autor: Zehentner, Ján; Macháč, Jan; Migliozzi, Maurizio
      (IEEE, 1998-05)
      This paper deals with an investigation of the dispersion characteristics of the slotline in the mm-wave range. Attention is paid to the possible excitation of the surface leaky waves on the slotline. Higher order leaky ...
    • Dispersion characteristics of leaky waves on lossless and lossy slotlines 

      Autor: Zehentner, Ján; Macháč, Jan; Migliozzi, Maurizio
      (IEEE, 1998-06)
      This paper deals with the dependence of the type of solution of the determinantal slotline dispersion equation on the location of the poles of its matrix elements. A number of possible solutions above the cut-off frequencies ...
    • Surface leaky waves and their measurement 

      Autor: Zehentner, Ján; Macháč, Jan; Mrkvica, Jan; Sarnowski, Marcin K.; Polívka, Jiří
      (IEEE, 1998-10)
      A new approach to experimental identification of surface leaky waves on printed-circuit lines is presented in this paper. Active radiometry is used for field probing even in the near field zone. The measurement is adjusted ...
    • A novel vector network analyzer 

      Autor: Hoffmann, Karel; Skvor, Zbyněk
      (IEEE, 1998-12)
      A calibration procedure for a perturbation two-port vector network analyzer is presented. It consists of a variable perturbation two-port placed between a device-under-test and a scalar network analyzer. A measured vector ...
    • The Distributed Oscillator at 4 GHz 

      Autor: Divina, Lukáš; Škvor, Zbyněk
      (IEEE, 1998-12)
      This paper describes the design and experimental verification of a tunable oscillator based on a microwave distributed amplifier. The oscillator met design expectations, being capable of continuous tuning over the range ...
    • Spurious leaky mode solutions and experimental verification of the second leaky wave 

      Autor: Zehentner, J.; Macháč, J.; Mrkvica, J.; Vacek, P.; Polívka, J.
      (IEEE, 1999)
      This paper presents the revelation of spurious leaky mode solutions of the dispersion equation, and experimental confirmation of the occurrence of the second leaky wave on the slotline. The appearance of the spurious ...
    • Space leakage of power from uniplanar transmission lines 

      Autor: Macháč, Jan; Zehentner, Ján
      (IEEE, 2000)
      Surface and space leakage of power deteriorates the operation of circuits. On the other hand space leaky waves enable the design of specific radiators. We therefore investigate the potential of the slotline and the coplanar ...
    • Properties of CPW in the sub-mm wave range and its potential to radiate 

      Autor: Zehentner, J.; Macháč, J.
      (IEEE, 2000)
    • New Space Leaky Wave Spectrum Components on the Slotline 

      Autor: Zehentner, Ján; Macháč, Jan
      (IEEE, 2000-10)
      Surface and space leakage of power deteriorates the operation of circuits. On the other hand space leaky waves enable the design of specific radiators. In this paper we therefore investigate the potential of the slotline ...
    • Leaky Wave Radiation of a Printed Slotline Antenna 

      Autor: Zehentner, Ján; Macháč, Jan; Lorenz, Petr; Mrkvica, Jan
      (IEEE, 2001)
      This paper presents a theoretical prediction of the field radiated from a uniplanar slotline antenna operating with the leaky wave. Discussion on a possible spectrum of space leaky waves is opened. Several antennas and ...