###### Abstract  
This article presents a parametric study using full-wave simulations about the potential use of cold plasma discharges to achieve frequency reconfiguration on a Sievenpiper mushroom metasurface. The study was done by inserting plasma tubes in between the patches of the mushroom structure, in three different positions with respect to the top of the metasurface, and varying the electronic density while keeping the plasma collision frequency. The obtained results show that it is possible to shift the stop-band generated by the metasurface around 25% towards lower frequencies for an electron density value inside the tubes of \(10^{14}\) cm\({}^{-3}\), when they are placed in between the top patches of the metasurface. Additional insertion losses are exhibited when operating near the plasma frequency.  
metasurface; cold plasma; frequency reconfiguration +
Footnote †: journal: Applied  
metasurface, it is necessary to integrate active tunable devices or tunable materials within the neighbor cells that can change the overall properties of the structure. For example, we can find the use of varactors or pin diodes to manipulate different properties of the metasurface [16; 17; 18] and the use of tunable materials such as liquid crystals and other ferroelectric materials to achieve reconfiguration [19; 20]. However, there is still a gap to be studied for topologies that can handle higher power densities for reconfiguration, in which plasma discharges can be a candidate [15].  
Plasma discharges are not new in terms of their use in high-frequency applications. The main characteristic of cold plasma discharges is that, when an electromagnetic wave is impinging on a plasma, it can be reflected, absorbed, or transmitted with a specific phase shift [21]. In other words, a plasma acts as a conducting or a dielectric material whose complex relative permittivity \(\varepsilon_{p}\) is a function of its electron density \(n_{e}\), its electron-neutral momentum transfer collision frequency \(\
u_{p}\), and the angular frequency \(\omega\) of the incident electromagnetic wave. Depending on these three parameters, the real part of \(\varepsilon_{p}\) can be negative, equal to zero, or positive with a value between 0 and 1. Such electromagnetic properties have led to several applications in the field of antennas and microwave circuits [22; 23; 24; 25]. In particular, plasma parameters can be controlled by external variables, such as the power injected to the discharge that has a direct influence on the electron density, and the gas pressure, and this has an influence over the plasma collision frequency [26]. This characteristic makes the cold plasma discharge suitable for the implementation of reconfigurable high-frequency devices, due to the active control and variation of the plasma permittivity, and therefore the variation of how the EM wave interacts with the discharge and the device [27; 28; 29; 30; 31; 32].  
In this study, we propose the assessment of a reconfigurable Sievenpiper mushroom metasurface [33] using plasma tubes as the active device by varying the electron density to achieve a frequency shift of the stop-band generated by the metasurface.