## 1 Introduction  
It has been a significant challenge to improve the capacity of wireless communication systems in current mobile networks to meet the demands of higher data rates, lower power consumption, and increased connectivity [1; 2; 3]. To address this challenge, various methods have been employed such as utilizing pattern reconfigurability through multiple switching radiators, phase shifting, beamforming, and the Butler matrix. These techniques have been implemented in both single-element and array configurations, as documented in [4; 5; 6; 7; 8; 9; 10; 11; 12]. Additional radiators on a single element, combined with appropriate switching mechanisms, are widely employed due to their ability to cover a wide range. This was especially evident in [6], where four PIN diodes were used to achieve nine states, but the coverage was limited to \(30^{\circ}\). Previous studies have reported on various antenna geometries with beam steering capabilities. For example, patch antennas integrated with additional radiating elements and RF switches [13; 14] achieved beam tilt in two states using three PIN diodes, resulting in peak gains of 8.2 dBi and 8.5 dBi, respectively. However, these configurations had limited operating bandwidths. Another study [15] explored a coverage of \(360^{\circ}\) using six radiating elements, but the operating bandwidth was constrained to 14.5%. Similarly, the planar structure covered four states [16; 17] and exhibited a wide bandwidth,but had a low gain of 2.8 dBi, only four working modes, and covered only 6.7% and 34% of the bandwidth in [16; 17], respectively. Planar antennas [18; 19; 20; 21; 22] such as the Vivaldi antenna have gained popularity due to their low degrees of cross-polarization, high directivity, and wideband characteristics. Similarly, ref. [23] used 16 PIN diodes to obtain a coverage of only 22.5\({}^{\circ}\), while in [24], the authors employed 16 PIN diodes to obtain 8% on bandwidth and a coverage of only 45\({}^{\circ}\).  
Furthermore, there is interesting potential in the advancement of optically transparent antennas to enhance their visual impact in urban environments by utilizing surfaces such as glazed structures such as building or car windows. Transparent antennas could also be utilized over larger surface areas to enhance their performance capabilities. These antennas can be created by printing transparent and conductive layers on glass or quartz as substrates. ITO is a widely used transparent and conducting oxide TCO material for this purpose [25]. Hybrid solutions, such as ITO/Cu/ITO multilayers [26] or AgHT films [27], have also been developed. Another alternative approach involves using a mesh metal printed onto a transparent material as a glass substrate, as developed in [28; 29; 30; 31].  
The present study aims to address these limitations by proposing a simplified Vivaldi structure that operates in the frequency range from 20 to 30 GHz. The proposed structure possesses a good degree of matching, has a soft visual impact, and covers the lower 5G bands. Note that we have utilized the structure presented in [32] as a starting point, albeit with modifications to the antenna size and implementation on a transparent substrate. Additionally, we have expanded the study by incorporating more states and investigating changes in the beam width and direction.  
The article continues with Section 2 which details the antenna design of the opaque passive antenna. Section 3 outlines the simulation results for the opaque passive antenna, while Section 4 focuses on the fabrication process of the transparent antenna. The results and discussion of the passive transparent antenna are presented in Section 5. Section 6 presents the design of the active transparent antenna, and the results and discussion of the active transparent antenna are presented in Section 7. Section 8 delves into the combination of states, while Section 9 examines the impact of the equivalent resistor of PIN control on the beamwidth. Finally, Section 10 concludes the article.