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RF energy harvester

  • US 9,837,865 B2
  • Filed: 08/08/2014
  • Issued: 12/05/2017
  • Est. Priority Date: 08/09/2013
  • Status: Active Grant
First Claim
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1. An apparatus comprising:

  • a rectifying circuit arranged to convert a variable electrical signal received at an input from an associated antenna into a direct current electrical signal for supplying to an electrical energy storage unit, the antenna for use in harvesting ambient radio frequency, RF, energy; and

    a power management module having an input arranged to receive the direct current and control supply of the direct current to the electrical energy storage unit;

    whereinthe rectifying circuit comprises a plurality of transmission lines, wherein the input of the rectifying circuit and the input of the power management module are connected via the plurality of transmission lines; and

    the power management module is arranged at least partially within a boundary defined by the plurality of transmission lines;

    characterised in that;

    the plurality of transmission lines form first and second arms, the first arm connecting the input of the rectifying circuit to the input of the power management module via a forward biased rectifying device, and the second arm connecting the input of the rectifying circuit to the input of the power management module via a reverse biased rectifying device;

    the first arm comprises a first transmission line that connects the input of the rectifying circuit to the forward biased rectifying device, and a second transmission line that connects the forward biased rectifying device to the input of the power management module;

    the power management module is connected at a first end to the output of the rectifying circuit;

    a distance between a second end of the power management module and the input of the rectifying circuit is between λ

    g/2.5 and λ

    g/5;

    a distance between a first side of the power management module is between λ

    g/6.5 and λ

    g/12 from an edge of the first arm; and

    a distance between a second side of the power management module is between λ

    g/9 and λ

    g/16.4 from an edge of the second arm;

    wherein λ

    g is a wavelength at a centre frequency of a respective frequency band arranged to be received by the antenna.

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