## 2 Related Work  
To establish a robust referential framework justifying this systematic review and meta-analysis, an in-depth critical analysis of several foundational studies related to RF energy-harvesting-oriented antenna and rectifier system development is performed. The analysis follows a chronological structure, clearly identifying technological and methodological evolution within this domain. Each article's employed methodology, quantitative or qualitative results, and primary limitations--either noted by the authors themselves or identified during critical review--are explicitly and thoroughly examined, as summarized in Table 1. \begin{table}
\begin{tabular}{c c c c} \hline
**Ref.** & **Approach** & **Employed Technique** & **Limitations** \\ \hline \multirow{8}{*}{[19]} & & Review of microstrip patch & No experimental validation or \\  & & antennas considering slot variations, & simulation results presented in this \\  & Comparative analysis of microstrip & dielectric properties, rectifier & work. Focused on qualitative \\  & patch antenna designs for rectennas & circuits, and reconfigurability. & comparison rather than quantitative \\  & used in RF energy harvesting. & Compiled efficiency and harmonic & benchmarking. Limited to microstrip \\  & & suppression data. Comparative & antenna technology; does not include \\  & & evaluation of antenna geometry and & other antenna types or broader energy \\  & & performance. & harvesting systems. \\ \hline \multirow{8}{*}{[20]} & & Categorized receiver architectures & \\  & & (time-switching, power-splitting), & \\  & Comprehensive survey on wireless & propagation models (Friis, & meta-analysis or unified benchmarking \\  & networks with RF energy harvesting & Rayleigh), and communication & across implementations. Hardware \\  & capability (RF-EHN). & scheduling. Reviewed energy & circuit designs are referenced but not \\  & & sources, matching networks, and & deeply reviewed. Primarily conceptual \\  & & circuit efficiency with & and qualitative. \\  & & experimental data. & \\ \hline \multirow{8}{*}{[21]} & & \multirow{8}{*}{Comprehensive review of energy harvesting techniques and prediction models for wireless sensor n networks (WSNs).} & Extensive review of energy sources (RF, solar, thermal, etc.) and predictive models. Presented case studies and analyzed energy forecasting models for WSN implementations. & Does not include statistical meta-analysis; lacks unified metrics for quantitative comparison across energy harvesting systems. Focuses on survey and taxonomy, with limited \\  & & & benchmarking data or performance synthesis. \\ \hline \multirow{8}{*}{[22]} & & Reviewed energy sources, harvesting models, scheduling & No statistical meta-analysis or benchmarking tables provided. High \\  & harvesting communications from energy sources to network & networking frameworks. Explored optimization strategies and hybrid energy systems across layers. & specific sections. Focus is conceptual \\  & & & optimization strategies and hybrid energy systems across layers. & and modeling oriented; lacks \\ \hline \multirow{8}{*}{[23]} & & \multirow{8}{*}{Comprehensive survey on energy harvesting systems, especially for IoT sensor applications.} & Comparative analysis of antenna topologies (patch, metamaterial), matching networks (L, Pi), and rectifier architectures (diode-based, MOSFET-based). Presented trade-offs in miniaturization, reconfigurability, and rectifier efficiency. & Review lacks quantitative meta-analysis and experimental benchmarking. \\ \cline{1-1}  & & & \\ \cline{1-1}  & & & \\ \cline{1-1}  & & & \\ \cline{1-1}  & & & \\ \cline{1-1}  & & & \\ \cline{1-1}  & & & \\ \cline{1-1}  & & & \\ \cline{1-1}  & & & \\ \cline{1-1}  & & & \\ \cline{1-1}  & & & \\ \hline \end{tabular}
\end{table} 
Table 1: Summary of related works on advances in antenna and rectifier systems for RF energy harvesting. [PERSON] et al. [19] conducted one of the earliest studies focusing on antennas for RF rectennas.