20-07-2013, 03:32 PM
RECTENNA DESIGN FOR MICROWAVE ENERGY RECYCLING
RECTENNA DESIGN .pptx (Size: 464.47 KB / Downloads: 46)
INTRODUCTION
A rectenna is a rectifying antenna, a special type of antenna that is used to convert microwave energy into direct current electricity. They are used in wireless power transmission systems that transmit power by radio waves.
A simple rectenna element consists of a dipole antenna with an RF diode connected across the dipole elements.
The diode rectifies the AC current induced in the antenna by the microwaves, to produce DC power, which powers a load connected across the diode.
Schottky diodes are usually used because they have the lowest voltage drop and highest speed and therefore have the lowest power losses due to conduction and switching.
HISTORY
Over 100 years ago, the concept of wireless power transmission began with the patented ideas and demonstrations by Tesla and Hertz.
Although Tesla was unsuccessful at implementing his wireless power transmission systems for commercial use, he did transmit power from his oscillators that operated up to 100 MV at 150 kHz.
To concentrate the transmitted power and to increase transmission efficiency, we have to use higher frequency than that used by Tesla. In 1930s, much progress in generating high power microwaves, 1-10 GHz radio waves, was achieved by invention of the magnetron and the klystron.
RECTENNA DESIGN
This part describes the design and results of simulations of a single rectenna working at ISM band center in 2.4 GHz. First a brief background about simulation methods used are presented, involving microstrip antennas and rectifier circuits.
As antenna was chosen to be a microstrip square patch aperture coupled antenna, the design will have lower dimensions and better polarization bandwidth that a traditional of this kind, this is achieved using a cross-slot in the patch and two feed line each for one polarization, this is to increase the range of incident power; then a dual linear polarization antenna was achieved.
As a rectifier Villard voltage doubler was chosen.
CONCLUSION
As a conclusion of this work there are two main aspects to mention. First this work shows that a rectenna can be simulated using harmonic balance simulation for the circuit by chosen properly model-library components, and Electromagnetic simulators for the antenna part, being careful with the higher coupling sensibility between antenna and circuit.
Second, the measured results presented indicate that rectennas might work as RF recyclers with an output power level enough to be efficiently stored and reused, in our case specially working in 2.45 GHz. ISM band.