Now showing items 1-20 of 58

    • A Double H-Shaped Resonator for an Isotropic ENG Metamaterial 

      Author: Macháč, Jan; Rytíř, Martin; Protiva, Pavel; Zehentner, Jan
      (IEEE, 2008-10)
      This paper presents a new planar particle showing negative effective permittivity under irradiation by an electromagnetic wave. The response of this particle, aimed to be sensitive to an electric field, is strongly ...
    • A New Concept of PTP Vector Network Analyzer 

      Author: Závodný, Vadim; Hoffmann, Karel; Škvor, Zbyněk
      (IEEE, 2004-12)
      A new concept for vector network analyzers design based on a perturbation two-port (PTP) is presented. The approach uses redundant states of the PTP. The best states of the PTP for a certain place in Smith chart and frequency ...
    • A novel vector network analyzer 

      Author: 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 ...
    • A Planar Version of A Slotline Leaky Wave Antenna with a Stacked Substrate 

      Author: Macháč, J.; Pavliš, A.; Houška, M.; Zehentner, J.
      (IEEE, 2008-05)
      This paper presents a new version of a leaky wave antenna based on a conductor-backed slotline with a stacked substrate. The advantage of this new structure is its flat top surface, due to the antenna being fed from the ...
    • A Simple Ultra-Wideband Suspended Stripline Bandpass Filter With Very Wide Stop-Band 

      Author: Balalem, Atallah; Menzel, Wolfgang; Macháč, Jan; Omar, Abbas
      (IEEE, 2008-03)
      This letter introduces a simple ultra-wideband suspended stripline filter with a pass-band from 3.1 to 10.6 GHz and a very wide stop-band up to more than 25 GHz. The filter is realized by capacitive coupling of a quasi-lumped ...
    • Active Resonator 

      Author: Hoffmann, Karel; Škvor, Zbyněk
      (IEEE, 2001-07)
      A new electrical component-active resonator-is designed. The component consists of a common passive resonant circuit whose losses are compensated by an extra active circuit. Experimental verification was done with a TE/sub ...
    • Analysis of discontinuities in waveguiding structures by MAB method 

      Author: 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 ...
    • Bandpass Filters on a Modified Multilayer Coplanar Line 

      Author: Balalem, Atallah; Hamad, Ehab K. I.; Macháč, Jan; Omar, Abbas S.
      (IEEE, 2006-06)
      The design of compact multilayer coplanar line bandpass filters is presented. These very compact filters make use of the two sides of the substrate of the modified coplanar line. In addition, a transmission zero has been ...
    • Comments on Representation of Surface Leaky Waves on Uniplanar Transmission Lines 

      Author: Macháč, Jan; Zehentner, Ján
      (IEEE, 2002-02)
      This paper compares partial waves approximating a surface leaky wave on a uniplanar transmission line with substrate surface waves supported by its substrate. It is shown that their field distributions and the propagation ...
    • Coplanar Waveguide Transmitting a Left-Handed Wave 

      Author: Macháč, Jan; Hudlička, Martin; Zehentner, Ján; Spiliotis, Nikolaos G.; Omar, Abbas S.
      (IEEE, 2005-10)
      This paper presents a new version of a coplanar waveguide that transmits a left-handed wave. The equivalent circuit of the line unit cell has been derived from the shape of the layout. The values of its elements were ...
    • Coupling of split ring resonators in a mu-negative volumetric metamaterial 

      Author: Macháč, J.; Zehentner, J.; Bláha, M.
      (IEEE, 2008-06)
      This paper presents an experimental and theoretical study of the coupling of split ring resonators, and aims to show ways to widen the frequency band of the response of mu-negative metamaterials. The behaviour of these ...
    • Dispersion characteristics of leaky waves on lossless and lossy slotlines 

      Author: 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 ...
    • Dispersion Characteristics of the Dominant Mode on a Completely Shielded Conductor-Backed Slotline 

      Author: Zehentner, Ján; Macháč, Jan; Mrkvica, Jan
      (IEEE, 2004-06)
      This paper presents an analysis of a completely shielded conductor-backed slotline using the spectral domain technique. Attention is paid to dominant and higher order modes with even symmetry of the transversal electric ...
    • Effect of feedback carrier excitation on LED external quantum efficiency 

      Author: 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 ...
    • Evaluation and Correction of Cable Phase Stability in High Frequency Near-Field Measurement 

      Author: Vancl, Jan; Černý, Petr; Škvor, Zbyněk; Mazánek, Miloš
      (IEEE, 2008-04)
      In case of the near-field measurement, the radiated field by the measured antenna is received by two- dimensional scanner in defined points. During the process of the field scanning, the cable between the VNA and the scanner ...
    • Even and Odd Modes on a Conductor-Backed Slotline 

      Author: Zehentner, Ján; Macháč, Jan; Mrkvica, Jan
      (IEEE, 2002-09)
    • Evolution of New Real and Complex Improper Solutions of the Slotline Dispersion Equation 

      Author: 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 ...
    • First results of microwave measurement of broadband radio interference filters 

      Author: Hoffmann, Karel; Škvor, Zbyněk
      (IEEE, 2004-12)
      A vector measurement method for testing multiport interference filters for shielded chambers has been used. Measured data up to 3 GHz are presented. The authors believe that this is the first time such results have been published.
    • Flat Waveguide with a Longitudinal Slot 

      Author: Zehentner, Ján; Mrkvica, Jan; Macháč, Jan
      (IEEE, 2005-06)
      This paper presents an analysis of a flat slotted waveguide by the spectral domain method finalized by a complex root search procedure. Matching of fields from bounded and unbounded regions at the common interface is ...
    • Hidden Problems in Precise Calibration on Microstrip 

      Author: Raboch, Jiří; Hoffmann, Karel; Škvor, Zbyněk; Hudec, Přemysl
      (IEEE, 2008-12)
      A study of calibration problems on microstrip with respect to interaction of electromagnetic fields around SMA to microstrip launcher and microstrip short was carried out in frequency band up to 26 GHz. Omni Spectra SMA ...