# A Frequency- and Power-Dependent Semi-Analytical Model for Wideband RF Energy Harvesting Rectifiers

## TL;DR

This paper introduces a new model to predict the output voltage of RF energy harvesters based on frequency and power, improving design efficiency.

## Contribution

A semi-analytical model integrating frequency and power effects with S11 data for accurate wideband RF energy harvesting predictions.

## Key findings

- The model achieved over 95% agreement with simulations for output voltage predictions.
- It accurately captured trends across 0.5–3 GHz and input powers from −12 dBm to 0 dBm.
- The model reduces reliance on electromagnetic simulations for RF energy harvesting design.

## Abstract

In this study, a new semi-analytical model was developed that can calculate the output voltage of low-power microwave rectifiers as a function of frequency and input power. The model integrates diode rectification characteristics and frequency-dependent impedance mismatches within the same mathematical structure. Defined by second-order polynomial expressions for input power and frequency, the model directly incorporates reflection coefficient (S11) data into the equations to account for frequency-dependent power losses caused by impedance mismatch, thereby improving calculation accuracy under wide-band conditions. To validate the model, a wide-band rectifier prototype with an FR4-based T-type matching network and a voltage doubler structure was designed and manufactured. Model calculations showed over 95% agreement with simulation results and closely followed the measured output voltage trends over the 0.5–3 GHz frequency range and input power levels from −12 dBm to 0 dBm. The proposed model provides a design-oriented and computationally efficient tool for wide-band, low-power RF energy harvesting and wireless power transfer applications, enabling rapid evaluation of impedance matching strategies with reduced reliance on electromagnetic simulations.