Off-Center-Fed Patch Rectenna for Impedance Matching
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Solution Overview
Problem
Existing wireless power transfer systems face inefficiencies and complexity due to the need for impedance matching networks, which are costly, heavy, and sensitive to varying input power levels and load impedances, especially in broadband and multi-band rectenna systems.
Innovation Solution
The development of adaptive rectennas with tunable load impedances and direct impedance matching between antennas and rectifying circuits, eliminating the need for complex impedance matching networks, and utilizing off-center-fed patch antennas with shorting elements to achieve high RF-to-DC power conversion efficiencies across a wide range of frequencies and power levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If impedance matching networks are used to achieve high power conversion efficiency, then RF-to-DC conversion efficiency is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the impedance matching network from the rectenna system by directly integrating the antenna and rectifying circuit. The antenna is designed with specific geometric parameters and feeding structures that provide inherent impedance matching to the rectifier, removing the need for separate matching networks and simplifying the overall system while maintaining high conversion efficiency.
Solution Approach 2:
The patent merges the antenna and rectifying circuit into a single integrated rectenna structure. The antenna elements are directly connected to the rectifier diodes without intermediate matching networks, combining the functions of wireless signal reception and RF-to-DC conversion into one unified component, thereby reducing complexity and improving efficiency.
2Loss of energy
If impedance matching networks are used to match varying load impedances, then power conversion efficiency is improved, but weight and cost increase
Solution Approach 1:
The patent removes the heavy impedance matching networks from the system by designing antennas with inherent impedance characteristics that naturally match the rectifier input impedance. This extraction of the matching network eliminates unnecessary weight while maintaining efficient power transfer across varying load conditions through the integrated design.
3Adaptability or versatility
If broadband antennas are used to operate over varying frequencies, then versatility is improved, but impedance matching complexity increases
Solution Approach 1:
The patent combines broadband antenna design with integrated rectifying circuits in a unified rectenna structure. The antenna geometry and feeding structures are specifically designed to provide wideband impedance characteristics that naturally match the rectifier across multiple frequency bands, eliminating the need for complex frequency-dependent matching networks and enabling versatile operation without increased complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables high RF-to-DC power conversion efficiencies of at least 60% across various frequency bands and power levels without the need for complex matching networks, resulting in compact, lightweight, and cost-effective wireless power transfer systems compatible with printed circuit board integration.
Implementation Method 1
rectifying circuits or rectifiers, and techniques for eliminating impedance matching networks connected between the broadband antennas and the rectifying circuits
Implementation Method 2
structure for receiving electromagnetic (EM) radiation, for example, RF signals
Data Source
Figure 1A~1B
Figure 1C
Figure 2A~2C
AI summary
A rectenna for high efficiency RF-to-DC wireless energy harvesting that includes an off-center-fed patch (OCFP) antenna and a rectifying circuit. The input impedance of the antenna may be tunable and directly conjugate matched to an impedance of the rectifying circuit over a wide range of frequencies and/or under different operating conditions. An impedance matching network required by rectenna systems may therefore be eliminated using the methods disclosed for the design and implementation of the OCFP rectenna. The OCFP rectenna offers consistently high RF-to-DC power conversion efficiency over a wide range of frequencies and under different operating conditions.