###### Abstract  
A continuously reconfigurable metasurface reflector based on unit cell mushroom geometry that was integrated with a varactor diode is presented in this paper. The unit cell of the metasurface was designed and optimized to operate in the X-band and Ku-band, improving satellite communication's quality of service. The losses mechanisms of continuous control over the unit cell phase reflection in beam steering resolution are considered and the analysis results are presented. The unit cell design parameters were analyzed with an emphasis on losses and dynamic reflection phase range. The unit cell magnitude and phase reflection are shown in the wide frequency bandwidth and showed a good agreement between all the measurements and the simulations. This metasurface enabled a high dynamic range in the unit cell resonant frequency range from 7.8 to 15 GHz. In addition, the reflection phase and absorption calibration are demonstrated for multiple operating frequencies, namely, 11 GHz, 12 GHz, and 13.5 GHz. Furthermore, design trade-offs and manufacturing limitations were considered. Finally, a beam-steering simulation using the designed metasurface is shown and discussed. beam steering; Ku-band; metasurface; tunable circuits and devices +
Footnote †: email: [EMAIL_ADDRESS]  
Footnote †: email [EMAIL_ADDRESS]  
Footnote †: email: abramovich@gmail. loss mechanisms in the MS applications based on continuous control over the reflection phase values of the unit cell:  
1. Phase errors resulting from the dynamic reflection phase range of less than 360\({}^{\circ}\). 2. The unit cell resistance \(R\) causes losses, mainly at phase values around the \(f_{res}\). The chosen method for tuning capability parameter is defined as \(TC\) and the parameter of the unit cell \(Q\)-factor as \(Q\). The unit cell dynamic reflection phase range is proportional to \(TC\times Q\); therefore, a small \(TC\) can be compensated by increasing the \(Q\). It also increases unit cell losses proportional to \(R\times Q\)[11]. On the other hand, a large \(TC\) allows for a reduction in \(Q\) and unit cell losses while maintaining a high dynamic phase reflection range. Several methods add reconfiguring and tuning to MS, such as PIN switches, MEMS switches, liquid crystal materials, piezoelectric materials, and varactor diodes [8; 9; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22]. The liquid crystal method is used in the K-band and above and can be realized in MS as a tuning dielectric substrate, without any external element in the front, but is more challenging to implement [16]. The dielectric constant is the fundamental parameter, which changes in the liquid crystal tuning method. This parameter varies slightly in the order of tens of percent with a relatively low \(TC\). Thus, increasing the \(Q\) of the unit cell compensates for the inherent low tunability and allows for a significant dynamic phase range, but increasing \(Q\) also increases the losses, frequency dispersion, sensitivity to tolerances, and decreases bandwidth [16]. The liquid crystal has a slow response time, which is slower than the diode varactors' and switches' response times by several orders of magnitude [23]. Thus, liquid crystal is less suitable for continuous tracking and switching applications. Piezoelectromechanical system (MEMS) materials enable continuous changes in the unit cell thickness depending on the DC voltage [12; 22]. Thus, the properties of the MS continuously change as well. Using the piezo MEMS method is limited because it involves a physical change in the unit cell size. In addition, a high voltage of up to 200 V is needed for the control [22]. Several methods of tuning for digital coding MS applications are with quantization control over the unit cell reflection phase, mainly switches. The PIN switch enables frequency work up to 70 GHz, with a fast switching time, high reliability, low cost, and low control voltage of switches for digital coding MS applications with quantization control over the unit cell reflection phase [24; 25].