Impedance-Tunable Printed Antenna for Rectenna Use
At the Holst Centre on the High Tech Campus in Eindhoven research is carried out in the fields of Wireless Autonomous Transducer Solutions (WATS) and Systems in Foil (SIF). Within the WATS program, one of the research topics is wireless, RF energy transfer. Through the reception of ambient RF energy (GSM, DTV, WLAN, etc.) or the reception of dedicatedly transmitted RF signals, low-power sensors are directly powered or batteries are charged over distances ranging from a few decimetres to many meters. The focus in this research is on DC voltage maximization over large distances and on DC power maximization on intermediate (1-3m) distances.
A rectenna, i.e. a rectifying antenna, consists of an antenna connected to a rectifying circuit, often a discrete Schottky diode or combination of such diodes. For compact and power-efficient designs the antenna needs to be complex conjugately matched to the rectifying circuit. Therefore, the antenna needs to have sufficient geometrical parameters for realizing this impedance without sacrificing the antenna properties. Such an antenna has been found in the (strip) folded dipole antenna with additional short circuits. The modeling of this modified folded dipole antenna has been undertaken by modifying the folded dipole transmission line model. It has been found that this model restricts the placement of the additional short circuits. It is believed that at the 'forbidden' short circuit positions, the antenna becomes a combination of a dipole and loop antenna. Through extending the analytical model with a loop model and verification through the use of full-wave analysis results and measurement of prototypes to be constructed, we want to improve on the antenna model.
The work in this project will be conducted at the Holst Centre premises and will be supervised by Huib Visser. A second supervisor will be appointed from the EM group and will provide for a regular consultancy and will guard the porject progress.