Design and fabrication of Coaxial Plasma Waveguide Filter with the ability to reconfigure the Frequency band

This study aims to present a new structure based on coaxial waveguide, which can change the bandwidth, return losses, and input impedance by changing the plasma parameters of the coaxial waveguide. This structure consists of a metal body and a gas tube inside it, which uses a high voltage alternating current converter, can change the plasma parameters and, consequently the waveguide parameters. The input and output of the waveguide are also designed using the indirect capacitive coupling method. In the Field of plasma research and related emerging technologies, recently, it has achieved a special place in various industries such as radar and Aerospace industries. The creation of telecommunication structures such as antennas and Waveguides with plasma, has given features such as adaptability, the ability to reconfigure the characteristics of the structure, and improve the sensitivity of this type of structure. By applying and changing the plasma excitation parameters, a change in the bandwidth was observed in the frequency band range of 0.5-4 GHz and a maximum of 1.38 GHz. Also, increasing the intensity of the excitation current improved the return losses in the resonance frequencies and, on the other hand, increased the band ripple. According to the results, the change of Plasma parameters depends on the change of plasma excitation frequency, and the value of Excitation current applied. As the Value of excitation current increases, the matching to the resonance frequencies improves, but on the other hand, the passband ripple of the plasma waveguide filter increases. As the plasma excitation pulse frequency increases, the bandwidth and resonance frequencies change to higher frequencies, and the matching to the resonance frequencies improves. But on the other hand, the passband ripple increases. This new waveguide filter can be used in cognitive/ adaptive telecommunication systems due to the constant change of frequency band.