Proximity Detection Using an Antenna and Directional Coupler Switch
AssigneeMicrochip Technology Incorporated
InventorDieter Peter
Life of this patent
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Abstract
Detection of an increase in a mismatch of an antenna of a radio frequency (RF) device and/or a change in a capacitance value of the antenna indicates proximity of a body to the antenna. Upon detection of proximity of a body to the antenna, reduction of transmit power of the RF device may be done to meet Specific Absorption Rate (SAR) level regulations.
Claims22
A directional coupler for coupling an antenna with a radio frequency (RF) system, comprising:
- a first connection for coupling the antenna to a directional coupler switch arranged within the directional coupler;
- a second connection for coupling the RF system to the antenna through the directional coupler switch;
- and
- a third connection for coupling the antenna to a capacitance measurement device through the directional coupler switch, wherein the capacitance measurement device measures capacitance values of the antenna.
A radio frequency device, comprising:
- a radio frequency subsystem;
- a power amplifier coupled to the radio frequency subsystem;
- a low noise amplifier coupled to the radio frequency subsystem;
- an antenna;
- and
- a directional coupler comprising
- a first connection for coupling the antenna to a directional coupler switch arranged within the directional coupler;
- a second connection for coupling the power amplifier to the antenna through the directional coupler switch;
- a third connection for coupling the low noise amplifier to the antenna through the directional coupler switch;
- and
- a fourth connection for coupling the antenna to a capacitance measurement device through the directional coupler switch, wherein the capacitance measurement device measures capacitance values of the antenna.
A method for determining proximity of a object to an antenna of a radio frequency device, said method comprising the steps of:
- measuring a capacitance value of the antenna;
- determining whether the measured capacitance value of the antenna has changed from a previous measurement of a capacitance value of the antenna;
- and
- detecting proximity of the object to the antenna when the capacitive value of the antenna has changed by at least a certain value.
A method for determining proximity of a object to an antenna of a radio frequency device, said method comprising the steps of:
- measuring a reflected voltage standing wave value of the antenna;
- determining whether the reflected voltage standing wave value of the antenna has changed from a previous measurement of a reflected voltage standing wave value of the antenna;
- and
- detecting proximity of the object to the antenna when the reflected voltage standing wave value of the antenna has changed by at least a certain value.
Dependencies are inferred from the claim text.