### Types of Antenna Systems Used in Underground Mining
#### 1.2.6 Wearable Antennas  
Wearable antennas are small, light antennas that can be embedded in wearable devices. They are built to receive and broadcast signals, allowing for the wearable devices to communicate with other devices like smartphones or Wi-Fi routers. Metals and conductive textiles are two commonly materials that can be used to make wearable antennas. [PERSON] et al. [50] proposed a wearable off-body antenna based on artificial magnetic conductor frequency selective surface (AMC-FSS) at 5.8 GHz for underground communication. The antenna has three layers, an AMC substrate, a planar monopole, and a FSS super substrate, and achieved a bandwidth of 1 GHz with a directivity of 54.9\({}^{\circ}\). In another study, [PERSON] et al. [51] improved the antenna's gain and directivity, achieving a band-width of 1.5 GHz with a directivity of 40.7\({}^{\circ}\).  
However, in addition to the research that has been conducted in designing antennas for effective communication and, ultimately, improved coverage, there are several issues that still require extensive research in designing an antenna system that should be efficient while posing minimal signal and coverage loss in underground mines. To overcome these challenges, smart antennas (critical components of communication systems) that can adapt to changing conditions in the underground mining environment must be developed. Modern wireless communication systems rely on multi-beam antennas to optimize their performance and achieve the desired output. These antennas have diverse applications across domains such as WLANs, base stations, satellite communications, and even automotive radars. In the context of 5G communication systems, multi-beam antennas have gained paramount importance. They enable wide-angle coverage while minimizing signal interference, making them crucial for ensuring efficient and reliable wireless communication. This study introduces a novel approach by proposing a smart antenna system specifically designed to address communication challenges in underground mines. In this paper, the current communication problems in underground mines were identified. A solution was proposed based on the existing literature. A smart antenna system was proposed to improve connectivity and coverage in underground mines. The proposed antenna was designed, and different parameters were analyzed to optimize their performance. As a result, we suggest using a four-element array with beam steering features to reduce signal interference and improve communication in underground mines.  
The paper is divided into sections that discuss various aspects of the investigation. Section 2 discusses the approach, antenna system design, and Butler matrix components. This section also addresses the structure and operation of each component of the Butler matrix. Section 3 contains comprehensive details about the optimized outcomes of each Butler matrix component designed at 5.8 GHz, including the hybrid coupler, crossover, and phase shifter parameters. This section also covers the antenna design transition a from rectangular to a square patch design and provides an in-depth evaluation of the antenna array using the Butler matrix. Furthermore, the proposed antenna's practical use is thoroughly investigated. Finally, in Section 4, an in-depth conclusion is offered to summarize this study's findings.