Planar flexible rf tag and charging device

Abstract

A planar flexible ultra-wide band (UWB) RF antenna includes a flexible non-electrically-conductive substrate and at least one antenna patch having electrically conductive metal positioned on one side of the flexible non-electrically-conductive substrate and having geometry defining a wirelessly transmitted UWB signal. The antenna may electrically couple with an RF transmitter circuit formed on a second side of the flexible substrate and controlled by a microcontroller circuit, formed on the second side, to transmit a radio signal. The RF tag may include at least one decoupling circuit directly electrically connected to the RF antenna and having a decoupling frequency that is different from a transmitting frequency of the antenna. The decoupling circuit transfers power from the antenna when the antenna receives capacitive power from an external non-electrical contact charger operating at the decoupling frequency and having at least one plate of similar geometry to the at least one antenna patch.

What is claimed is: 
     
         1 . A dual-purpose antenna, comprising:
 first and second antenna elements that are electrically conductive and configured to:   (i) one or both of transmit and receive a wireless signal at a transmission frequency, the first and second antenna elements having a propagation pattern defined by an antenna geometry of the first and second antenna elements, and   (ii) receive a charging signal capacitively-coupled across a first capacitor formed in part with the first antenna element and a second capacitor formed in part with the second antenna element.   
     
     
         2 . The dual-purpose antenna of  claim 1 , the antenna geometry including:
 a size and shape of each of the first and second antenna elements; and   a spacing between the first and second antenna elements.   
     
     
         3 . The dual-purpose antenna of  claim 1 , further comprising a non-electrically-conductive substrate, the first and second antenna elements being located on a surface of the non-electrically-conductive substrate. 
     
     
         4 . The dual-purpose antenna of  claim 3 , the non-electrically-conductive substrate being flexible. 
     
     
         5 . The dual-purpose antenna of  claim 1 , the first and second antenna elements comprising metal patches. 
     
     
         6 . A wireless device, comprising:
 the dual-purpose antenna of  claim 1 ;   a first decoupling circuit electrically coupled to the first antenna element and operable to decouple the charging signal at a charging frequency less than the transmission frequency; and   a second decoupling circuit electrically coupled to the second antenna element and operable to decouple the charging signal at the charging frequency.   
     
     
         7 . The wireless device of  claim 6 , further comprising:
 a first full wave rectifier half electrically coupled to the first decoupling circuit;   a second full wave rectifier half electrically coupled to the second decoupling circuit; and   a regulator circuit electrically coupled to outputs of the first and second full wave rectifier halves to regulate rectified electrical power outputted by the first and second full wave rectifier halves.   
     
     
         8 . The wireless device of  claim 7 , further comprising a rechargeable battery for storing energy outputted by the regulator circuit. 
     
     
         9 . A charging device for charging the wireless device of  claim 6 , the charging device comprising:
 a dielectric layer;   first and second metal plates located on the dielectric layer and having a charger geometry corresponding to the antenna geometry;   a variable oscillator;   a first inductor electrically coupled to the first metal plate and a first output of the variable oscillator;   a second inductor electrically coupled to the second metal plate and a second output of the variable oscillator; and   a microcontroller, electrically coupled to the variable oscillator, that controls the variable oscillator to drive the first and second metal plates to capacitively couple the charging signal to the first and second antenna elements.   
     
     
         10 . The charging device of  claim 9 ,
 further comprising a current sensor that is electrically coupled with the microcontroller and senses current through one or both of the first and second inductors;   wherein the microcontroller, based on the sensed current, controls the variable oscillator to operate at a resonance frequency determined in part by the first and second capacitors.