In this review paper, the design and implementation of antenna types in wide band frequencies for ocean communication are analysed. This work mainly concentrates on designing a high frequency wide band antenna which has high directivity, omni directional radiation pattern, small size and good time domain performances.

Recently, high-speed multimedia communication systems have become widespread. Not only conventional narrow band speech signal (up to 3.4 kHz) but also wide band speech signal (up to 7 kHz) can be transmitted through high-speed communication lines. Generally, the quality of wide band speech signal is high and its articulation score is good for normal-hearing people, but for elderly people who ha...

Simultaneous-masked psychophysical tuning curves were obtained from normal-hearing listeners using low-level (20-25 dB SPL) probe tones in quiet and high-level (60 dB SPL) probe tones, both in quiet and in the presence of a broad-band background noise. The background noise was introduced to eliminate combination tones or combination bands and other off-frequency listening cues that exist at hig...

Two kinds of band-notched ultra wide-band slot antennas are proposed. Printed on a dielectric substrate of FR4 with relative permittivity of 4.4 and fed by a 50 Ω microstrip line, the proposed antennas introduce semicircular annular strips to reject the frequency band (5.15–5.85 GHz) limited by IEEE802.11a. The parameters which affect the performance of the antennas in terms of its frequency do...

The analysis and optimization of the npvnp avalanche diode structure that includes two avalanche regions have been realized on basis of the nonlinear model and special optimization procedure. The admittance and energy characteristics of the DAR diode were analyzed in very wide frequency band from 30 up to 360 GHz. Output power level was optimized for the second frequency band near the 220 GHz.

The analysis and optimization of the npvnp avalanche diode structure that includes two avalanche regions have been realized on basis of the nonlinear model and special optimization procedure. The admittance characteristics of the DAR diode were analyzed in very wide frequency band from 30 up to 360 GHz and had been optimized for the third frequency band near the 300 GHz.

The goal of bandwidth extension of speech (BWE) is to extrapolate the missing low or high frequency components of the wide-band speech (50-8000 Hz) based entirely on information contained in a narrow-band signal (300-3400 Hz). In this paper we propose a new method for high-frequency regeneration of the excitation signal, using the correlation between the shape of the glottal flow waveform and t...