## 2 Related Work
\begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline
**Ref.** & **Approach** & **Employed Technique** & **Limitations** \\ \hline \multirow{8}{*}{[24]} & \multirow{8}{*}{Taxonomic survey of energy harvesting systems for wireless sensor networks.} & Systematic review of 137 research articles (1998–2020). Classified EH systems into types (solar, RF, thermal, etc.) and provided further breakdown by transducer type and storage method. Conducted bibliometric and mapping analysis. & Focus is mainly on classification and taxonomies. Does not present meta-analytical statistics. Limited to WSN applications and lacks detailed performance benchmarking across all compared methods. \\ \hline \multirow{8}{*}{[5]} & \multirow{8}{*}{Comprehensive review of rectenna antenna design techniques for RF energy harvesting (RFEH) and wireless power transfer (WPT).} & Categorized rectennas by topologies (single-band, multiband, broadband), impedance matching (lumped, hybrid), and radiation characteristics (gain, polarization). Comparative analysis of bandwidth trade-offs for various applications (WPT vs. RFEH). & Survey focuses on antenna design; does not include rectifier circuitry in depth. Lacks experimental validation or unified benchmarking. Does not provide a meta-analytical synthesis of performance across frequency bands or application contexts. \\ \hline \multirow{8}{*}{[25]} & \multirow{8}{*}{Review of synthesis, characterization, and development of energy harvesting techniques integrated with antennas.} & Explored antenna types (patch, coplanar waveguide (CPW)-fed), matching networks, rectifier configurations, and hybrid harvesting techniques (thermoelectric, piezoelectric, RF). Proposed rectenna architectures and hybrid harvester circuits with performance metrics. & Lacks experimental meta-analysis and performance standardization across case studies. High technical breadth may limit practical deployment focus. Does not explore long-term performance in real-world sensor networks. \\ \hline \multirow{8}{*}{[26]} & \multirow{8}{*}{Comprehensive review of RF energy harvesting technologies with emphasis on design techniques and potential applications.} & Analyzed antenna configurations (broadband, multiband), rectifier types (Dickson, Greniacher), and frequency bands (200 MHz to 5.8 GHz). Provided taxonomy-based assessments of efficiency, gain, and multiband configurations. & Review is largely qualitative without unified statistical meta-analysis. High technical breadth may limit depth in some aspects such as fabrication constraints. Focuses more on architecture and taxonomy than on end-to-end system deployment or real-time validation. \\ \hline \multirow{8}{*}{[27]} & \multirow{8}{*}{Comprehensive review of antenna technologies for ambient RF energy harvesting and wireless power transfer.} & Taxonomy-based review of antenna designs categorized by profile (low-profile, multiband), radiation performance, and fabrication methods (e.g., inkjet printing). Evaluated performance metrics (gain, efficiency) and design strategies (slotting, stacking). & Taxonomy-based review of antenna designs categorized by profile (low-profile, multiband), radiation performance, and fabrication full-system performance benchmarks. Focuses primarily on antenna-side design and architectural considerations. \\ \hline \end{tabular}
\end{table} 
Table 1: _Cont._a basis for understanding how to optimize it, but its scope was restricted to the antenna component and lacked experimental validation of each design's relative advantages. [PERSON] et al. [20] broadened perspective to wireless network contexts with RF harvesting capabilities. Their review comprehensively covered advancements up to that point in radio frequency energy harvesting networks (RF-EHNs). Specifically, they offered an overview of system architecture, RF harvesting techniques, corresponding receiver circuits, and communication protocols adapted for RF-powered networks.