## 3 Methodology: PRISMA for Information Filtering  
We employed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) method [28]. This approach ensured a comprehensive and unbiased selection of relevant studies from databases such as Web of Science, IEEE, Springer, Scopus, and others. The initial search yielded 2465 papers, which were systematically filtered based on their relevance to microstrip antennas and energy harvesting applications. * RQ1. What are the different types of antenna designs commonly used in energy harvesting applications, and what are their specific characteristics? The primary objective of this question is to gather comprehensive information about the various antenna designs employed in energy harvesting applications and to understand the unique characteristics of each design. This includes analyzing the design geometry, materials used, and performance metrics such as gain, efficiency, and bandwidth. * RQ2. What are the most commonly used frequency bands for RF energy harvesting in energy harvesting applications? This question aims to determine the most prevalent or effective frequency bands for energy harvesting using antennas in RF applications. Identifying these bands is crucial for understanding which frequencies are most suitable for different environments and applications, thereby optimizing the design and deployment of energy harvesting systems. * RQ3. What are the main rectifier systems used in converting energy captured by antennas in energy harvesting systems, and what are the key characteristics that influence their efficiency and conversion capacity? This question seeks to identify the most commonly used rectifier systems and their key characteristics in terms of efficiency and conversion capacity. Understanding these systems is vital for improving the overall efficiency of energy harvesting devices, as rectifiers play a crucial role in converting the captured RF energy into usable electrical power. Following the formulation of these research questions, we identified relevant keywords for our search: antenna, rectenna, energy harvesting, energy collecting, power transfer, wireless power transfer. Using these keywords, we constructed a research string (RS) as follows:  
\(\textbf{RS}=(\textit{antenna OR rectenna})\)\(\textit{AND}\)\((\textit{energy harvesting OR energy collecting OR power transfer OR wireless power transfer})\)  
Reference databases included Web of Science, Taylor and Francis, Springer, Scopus, ScienceDirect, SAGE, MDPI, and IEEE. These databases were selected based on the interdisciplinary nature of their publications and their relevance to the field of energy harvesting. We aimed to include all significant databases used by other authors in previous studies. Given the substantial number of articles obtained, no additional techniques were employed to increase the quantity of results. We applied the systematic process established in PRISMA method to filter scientific articles, as illustrated in Figure 1. This process ensured that only the most relevant and high-quality studies were included in our review. * **Identification:** During the first phase, we collected the metadata of the initially retrieved articles and subsequently applied systematic criteria to determine their inclusion or exclusion. These criteria were predefined to filter the literature relevant to the study's objectives. We started by excluding non-technical systematic reviews and state-of-the-art studies that lacked a strong technical foundation or presented analyses that were not suitable for the purposes of this study. * **Screening:** In the second phase, we examined the articles based on their title, abstract, and keywords. During this process, we excluded articles that were unrelated to our topic, as well as brief and irrelevant articles. We also eliminated articles that were not accessible or lacked sufficient information for our analysis.