Jugoslav P. Karamarkovic

Terahertz Performance of Integrated Lens Antennas With a Hot-Electron Bolometer

Radiation coupling efficiency and directive properties of integrated lens antennas with log-spiral, log-periodic, and double-slot planar feeds coupled to a hot-electron bolometer were experimentally studied at frequencies from 1 to 6 THz and compared with simulations based on the method of moments and physical-optics ray tracing. For all studied antennas, the modeled spectral dependence of the coupling efficiency fits to the experimental data obtained with both Fourier transform spectroscopy and noise temperature measurements only if the complex impedance of the bolometer is explicitly taken into account. At high frequencies, the radiation pattern of integrated antennas exhibits sidelobes, which are higher than those predicted by the antenna model

Statistical analysis of electrical breakdown time delay distributions in neon tube at 13.3 mbar

Results of the statistical analysis of the electrical breakdown time delay for a neon-filled tube at 13.3 mbar are presented in this paper. Experimental distributions of the breakdown time delay were established on the basis of 1000 successive and independent measurements, deviating from usual exponential distribution. Breakdown time delay distributions are numerically generated from the composition of two parameters, which correspond to the random variables of an exponential distribution and of a Gaussian distribution. Theoretical breakdown time-delay distribution is obtained from the convolution of the exponential and Gaussian distributions. The numerically generated and theoretical breakdown time delay distributions show good correspondence with the distributions of experimental data.

The application of convolution-based statistical model on the electrical breakdown time delay distributions in neon

Results of the statistical analysis of the electrical breakdown time delay for neon-filled tube at 6.5 mbar with and without /spl gamma/ and ultraviolet (UV) irradiation are presented in this paper. Experimental distributions of the breakdown time delay are established on the basis of 1000 successive and independent measurements for different exposition dose rates of /spl gamma/-irradiation, and UV illumination with known spectrum. Obtained experimental density distributions are modeled with convolution-based model, proposing two independent random variables with exponential and Gaussian distribution, respectively. The tendency of the breakdown time delay distribution to change shape from the exponential-like to the Gaussian-like is found by increasing the exposition rate of the /spl gamma/ irradiation. In addition, the characteristic strong reduction of the time delay is identified in the tube under the UV illumination.

The application of time delay method for analysis of processes which initiate electrical breakdown in 1.3 mbar nitrogen

The contributions of ions and neutral active states to secondary electron emission in the afterglow has been analyzed of the time delay method. The dependencies of mean value of time delay on relaxation time, overvoltage, and glow current have been discussed. The analysis of validity of Laue distribution for time delay has been performed, becoming the criterion for estimation of the main cause of breakdown. Thus, afterglow can be divided in three regions: one each for the role of charged and neutral species in initiation of subsequent breakdown, and third, as the transitional one.

Statistical analysis of the electrical breakdown time delay distributions in krypton

The statistical analysis of the experimentally observed electrical breakdown time delay distributions in the krypton-filled diode tube at 2.6mbar is presented. The experimental distributions are obtained on the basis of 1000 successive and independent measurements. The theoretical electrical breakdown time delay distribution is evaluated as the convolution of the statistical time delay with exponential, and discharge formative time with Gaussian distribution. The distribution parameters are estimated by the stochastic modelling of the time delay distributions, and by comparing them with the experimental distributions for different relaxation times, voltages, and intensities of UV radiation. The transition of distribution shapes, from Gaussian-type to the exponential-like, is investigated by calculating the corresponding skewness and excess kurtosis parameters. It is shown that the mathematical model based on the convolution of two random variable distributions describes experimentally obtained time delay ...

The application of convolution-based statistical model on the electrical breakdown time delay distributions in neon under /spl gamma/ and UV radiation

Results of the statistical analysis of the electrical breakdown time delay for neon-filled tube at 6.5 mbar with and without /spl gamma/ and ultraviolet (UV) irradiation are presented in this paper. Experimental distributions of the breakdown time delay are established on the basis of 1000 successive and independent measurements for different exposition dose rates of /spl gamma/-irradiation, and UV illumination with known spectrum. Obtained experimental density distributions are modeled with convolution-based model, proposing two independent random variables with exponential and Gaussian distribution, respectively. The tendency of the breakdown time delay distribution to change shape from the exponential-like to the Gaussian-like is found by increasing the exposition rate of the /spl gamma/ irradiation. In addition, the characteristic strong reduction of the time delay is identified in the tube under the UV illumination.

1D physically based non-quasi-static analog behavioral BJT model for SPICE

A compact 1D non-quasi-static BJT model (NQS BJT) based on the analog behavioral modeling capabilities of the SPICE simulator is described. The NQS BJT model parameters are derived directly from the physical device structure. A momentum relaxation time parameter is also included as equivalent inductivity, yielding more accurate prediction of unity gain frequency and phase characteristics. The efficiency of the novel NQS model is demonstrated by comparison with the standard Gummel-Poon model and experimental results.

The Application of Convolution-Based Statistical Model on the Breakdown Time Delay Distributions in Krypton

Summary form only given. The convolution-based model of the electrical breakdown time delay distribution is applied for the statistical analysis of experimental results in krypton-filled diode tube at 2.6 mbar. The electrical breakdown time delay distribution is obtained as the convolution of two random variables (statistical time delay with exponential and discharge formative time with Gaussian distribution). The distribution parameters are obtained by stochastic modeling of time delay distributions, and their comparison with experimental distributions. The breakdown time delay distributions are in good correspondence with the distributions obtained on the basis of 1000 successive and independent measurements. In order to follow transition from Gaussian to the exponential distribution corresponding skewness and kurtosis are plotted

Transient analysis of BJT using all injection level TLEC model

Transmission line equivalent circuit model of bipolar junction transistor has been generalized to include all injection level case and model Kirk effect. The obtained model has been used for simulation of time domain transient analysis.

Novel approximative analytical expressions for minority-carrier transit time including recombination

Abstract A novel analytical model for the minority-carrier transit time has been developed including the recombination effects. It has been found that the recombination effects substantially influence transit time in quasi-neutral regions with low effective contact recombination velocities and/or low minority-carrier diffusion length. In these cases, the difference of charge control concept transit time and the basic transit time definition have been analysed.