Compact Multi-band Antenna

Abstract

A multi-band antenna is disclosed that can operate in two different frequency bands through two different modes of operation. It can operate as a radio antenna for coupling energy into or out of a radio signal in a radio frequency band; or it can operate as a magnetic antenna for coupling energy into or out of a magnetic signal in a lower frequency band. A radio signal is a signal consisting of an electromagnetic wave; a magnetic signal is a signal consisting of a magnetic field. The multi-band antenna achieves the two modes of operation in a compact volume of space comparable to the volume of space occupied by an equivalent single-band antenna.

1 . A dual-frequency antenna comprising:
 a flat magnetic coil physically adapted for efficient antenna coupling with magnetically-coupled energy at a first frequency,   wherein the shape of the coil is also physically adapted for efficient antenna coupling with electromagnetic energy at a second frequency.   
     
     
         2 . The antenna of  claim 1  further comprising one or more sheets of electrically conductive material for enhancing antenna coupling with electromagnetic energy at the second frequency. 
     
     
         3 . The antenna of  claim 1  further comprising:
 a first input-output port for coupling a first electrical circuit with the magnetic energy at the first frequency, and 
 a second input-output port for coupling a second electrical circuit with the electromagnetic energy at the second frequency. 
 
     
     
         4 . The antenna of  claim 1  wherein the flat magnetic coil comprises multiple coil layers. 
     
     
         5 - 6 . (canceled) 
     
     
         7 . A radio-frequency identification device comprising:
 a dual-frequency antenna, wherein the dual-frequency antenna comprises   a flat magnetic coil physically adapted for efficient coupling with magnetic energy at a first frequency,   wherein the shape of the coil is also physically adapted for efficient coupling with electromagnetic energy at a second frequency.   
     
     
         8 . The radio-frequency identification device of  claim 7  further comprising:
 a first electrical circuit coupled with the magnetic energy at the first frequency through a first input-output port, and 
 a second electrical circuit coupled with the electromagnetic energy at the second frequency through a second input-output port; 
 wherein the first input-output port and the second input-output port are part of the dual-frequency antenna. 
 
     
     
         9 . The radio-frequency identification device of  claim 8  wherein the first electrical circuit and the second electrical circuit are the same circuit. 
     
     
         10 . The radio-frequency identification device of  claim 7  wherein the first frequency is used for energy scavenging. 
     
     
         11 . The radio-frequency identification device of  claim 7  wherein the second frequency is used for energy scavenging. 
     
     
         12 . The radio-frequency identification device of  claim 7  wherein the first frequency is in the Low-Frequency (LF) range and the second frequency is in the Ultra-High-Frequency (UHF) range. 
     
     
         13 . The radio-frequency identification device of  claim 7  wherein the first frequency is used for proximity operation, and the second frequency is used for long-range operation. 
     
     
         14 . The radio-frequency identification device of  claim 7  further comprising a housing that is suitable for attaching the device to an animal. 
     
     
         15 . The radio-frequency identification device of  claim 7  further comprising a housing similar in size and shape to a conventional credit card. 
     
     
         16 . A method for making a dual-frequency antenna, the method comprising:
 (i) designing an antenna for efficient coupling with electromagnetic energy at a first frequency, wherein the antenna design is based on one or more sheets of electrically conductive material; and   (ii) replacing, in the antenna design, at least part of one of the one or more sheets with a flat magnetic coil;   wherein the flat magnetic oil is designed so as to provide efficient coupling with magnetic energy at a second frequency.   
     
     
         17 . The method of  claim 16  further comprising:
 (iii) providing a first input-output port coupled with the magnetic energy at the first frequency, and a second input-output port coupled with the electromagnetic energy at the second frequency. 
 
     
     
         18 . The method of  claim 16  wherein the flat magnetic coil is designed with multiple coil layers. 
     
     
         19 - 20 . (canceled) 
     
     
         21 . The antenna of  claim 2  further comprising:
 a first input-output port for coupling a first electrical circuit with the magnetic energy at the first frequency, and 
 a second input-output port for coupling a second electrical circuit with the electromagnetic energy at the second frequency.