Showing papers by "Zvonimir Sipus published in 1999"
11 Jul 1999
TL;DR: In this article, the spectral domain approach was used to calculate the radiation pattern of an array of N/spl times/N patch antennas located above or inside a multilayer circular cylindrical structure.
Abstract: We have developed a computer program which calculates radiation patterns of an array of N/spl times/N patch antennas located above or inside a multilayer circular cylindrical structure by using the spectral domain approach. In the present paper, we use the program to study the effects of the curvature of the structure on the radiation pattern. The results show that the radiation pattern in the azimuthal direction is strongly dependent on the cylinder radius but much less so in the elevation direction. The results also show that the array exhibits high sidelobes which can be reduced by making the element spacing smaller than is necessary in the planar array.
9 citations
11 Jul 1999
TL;DR: In this paper, a variation of the "almost square" patch was proposed, which exhibits an axial radio of less than 2.5 dB over a more than 10% bandwidth.
Abstract: For more than 25 years the circularly polarized single-fed microstrip patch are considered to be extremely narrow-band. The performances reported are almost exclusively related to single-patches printed on a dielectric substrate, which partially explains the frequency characteristics. The antenna proposed is a variation of the 'almost square' patch and exhibits an axial radio of less than 2.5 dB over a more than 10% bandwidth. The antenna was designed for PCN and PCS applications.
6 citations
01 Oct 1999
TL;DR: In this paper, two bipolar transistors were placed along the resonant dimension and the spatial oscillator operated in push-pull mode to increase the power radiated by the antenna.
Abstract: The paper presents a new design of an active self-oscillating patch antenna. To increase the power radiated by the antenna two bipolar transistors were embedded in a rectangular opening inside a rectangular patch. The transistors were placed along the resonant dimension and the spatial oscillator operated in push-pull mode. Frequency tuning has been obtained by changing transistor dc bias voltage. The dependence of the operatlng frequency and radiated power on bias voltage as well as radiation patterns and free running spectra have been measured.
1 citations
01 Jan 1999
TL;DR: Svjetlovoda u komunikacijama. Mjerenje svjetloda optickim reflektometrom. Elektroopticki modulator.
Abstract: Svjetlovodi u komunikacijama. Mjerenje svjetlovoda optickim reflektometrom. Prijenos analogne informacije optickim vlaknom. Elektroopticki modulator.
1 citations
01 Jan 1999
TL;DR: In this paper, an active self-oscillating patchantenna was presented, where twobipolar transistors were embedded in a rectangular opening inside a rectangular patch to increase the power radiated by the antenna.
Abstract: The paperpresents a newdesign ofan active self-oscillating patchantenna. Toincrease the powerradiated bytheantenna twobipolar transistors wereembedded ina rectangular opening inside a rectangular patch. Thetransistors wereplaced along theresonant dimension andthespatial oscillator operated inpush-pull mode.Frequency tuning has beenobtained bychanging transistor dcbiasvoltage. The dependence oftheoperatlng frequency and radiated poweronbiasvoltage aswellasradiation patterns andfree running spectra havebeenmeasured.
11 Jul 1999
TL;DR: In this paper, a new method for calculating the reflection from multilayer cylinders was proposed, which is useful in analyzing structures that are not a full cylinder, such as curved radomes.
Abstract: We propose a new method for calculating the reflection from multilayer cylinders, which is useful in analyzing structures that are not a full cylinder, such as curved radomes. By using the black-hole approach the fields inside the innermost region of the structure are expressed in terms of only inward propagating waves, which corresponds to having an ideal termination (black hole) on axis. The calculated reflection from a dielectric cylinder and a dielectric tube show good agreement with the results obtained by using geometric optics.