جستجوی مقالات مرتبط با کلیدواژه « شکل موج مختلف » در نشریات گروه « برق »

Today, plasma technology has found significant applications in various industries including telecommunications. The high-ionization limit of plasma has made it a good conductor and a substitute for metal structures in high frequency. In recent years, the plasma environment for the design of reconfigurable antenna structures, waveguides, and frequency-selective surface (FSS) has received more attention by scientific societies, especially space and military centers. This is because of the specific characteristics of the plasma environment that can be used to control and adapt the antenna for different purpose. The effects of plasma usage on the antennas include: Improved sensitivity and Directivity, low Radar Cross Section (RCS), radiation pattern scaning, antenna array coupling and frequency tuning. Plasma can be created with many different ways: excitation with direct current, alternating current, surface wave driven. The purpose of this study was to investigate the effect of alternating current excitation with different frequency and waveform on U-shaped monopole plasma antenna parameters including: reflection coefficient, resonance frequencies and bandwidth. This type of excitation increases the operating frequency of the U-shaped antenna up to 2 GHz and its bandwidth in addition to its much lower power consumption. The signals sent or received from the antenna are applied to or received by a capacitive coupler to the plasma antenna. Also, by changing the frequency and waveform of excitation current (square, triangular, sinusoidal) of plasma, different results on antenna parameters were observed and measured, including: decrease reflection coefficient, central frequency shift and bandwidth change.