Proximity sensing using EHF signals
A system for sensing proximity using EHF signals may include a communication circuit configured to transmit via a transducer an EM signal at an EHF frequency, and a proximity sensing circuit configured to sense a nearby transducer field-modifying object by detecting characteristics of a signal within the communication circuit. A system for determining distance using EHF signals may include a detecting circuit coupled to a transmitting communication circuit and a receiving communication circuit, both communication circuits being mounted on a first surface. The transmitting communication circuit may transmit a signal toward a second surface, and the receiving communication circuit may receive a signal relayed from the second surface. The detecting circuit may determine distance between the first surface and a second surface based on propagation characteristics of the signals.
1. A communication system comprising:
a first amplifier configured to receive a radio frequency input signal and generate a first amplified output signal having an extremely high frequency (EHF) component;
a transducer having a first terminal and a second terminal operatively coupled to receive the first amplified output signal from the first amplifier, the transducer configured to transform the first amplified output signal to an electromagnetic signal operating in the EHF band of the electromagnetic frequency spectrum; and
a proximity-sensing circuit, comprising:
a reference circuit comprising a second amplifier coupled to receive the radio frequency input signal and generate a second amplified output signal having an EHF component, and an impedance component coupled to receive the second amplified output signal, and
a detection circuit configured to:
detect a reference amplitude voltage between a first terminal and a second terminal of the impedance component,
detect an amplitude of a composite signal voltage across the first terminal and the second terminal of the transducer,
compare the detected reference amplitude voltage and the detected amplitude of the composite signal voltage, and
generate an indication of proximity of the communication system to an object based on the comparison.
2. The system of claim 1 , wherein the impedance component has a value equivalent to an impedance of the transducer when the object is in a reference position relative to a position of the transducer.
3. The system of claim 1 , further comprising a first transformer coupled between an output of the first amplifier and the first and second terminals of the transducer.
4. The system of claim 1 , further comprising a second transformer coupled between an output of the second amplifier and the first and second terminals of the impedance component.
5. The system of claim 1 , wherein the transducer is an antenna.
6. The system of claim 1 , wherein the impedance component is a resistor.
7. The system of claim 1 , wherein the indication corresponds to an impedance change in the transducer caused by the presence of the object.
8. The system of claim 1 , wherein the detection circuit is further configured to:
compare a difference between the detected reference amplitude voltage and the detected amplitude of the composite signal voltage with a specified threshold reference level; and
generate the indication of proximity of the communication system to the object based on the comparison of the difference between the detected reference amplitude voltage and the detected amplitude of the composite signal voltage with a specified threshold reference level.
9. The system of claim 1 , wherein the first amplifier and the second amplifier are equivalent components.
10. The system of claim 1 , wherein the first transformer and the second transformer are equivalent components.
11. A method comprising:
receiving a radio frequency input signal;
amplifying the input signal by a first amplifier to generate a first amplified output signal having an extremely high frequency (EHF) component;
transforming, by a transducer, the first amplified output signal into an electromagnetic signal operating in the EHF band of the electromagnetic frequency spectrum;
receiving, by a proximity-sensing circuit, the input signal;
generating, by the proximity-sensing circuit, a second amplified output signal having an EHF component;
detecting a reference amplitude voltage between a first terminal and a second terminal of an impedance component coupled to receive the second amplified output signal;
detecting an amplitude of a composite signal voltage across a first terminal and a second terminal of the transducer;
comparing the detected reference amplitude voltage and the detected amplitude of the composite signal voltage; and
generating an indication of proximity of the communication system to an object based on the comparison.
12. The method of claim 11 , wherein the impedance component has a value equivalent to an impedance of the transducer when the object is in a reference position relative to a position of the transducer.
13. The method of claim 11 , wherein the transducer is an antenna.
14. The method of claim 11 , wherein the impedance component is a resistor.
15. The method of claim 11 , wherein the indication corresponds to an impedance change in the transducer caused by the presence of the object.
16. The method of claim 11 , further comprising:
comparing a difference between the detected reference amplitude voltage and the detected amplitude of the composite signal voltage with a specified threshold reference level; and
generating the indication of proximity of the communication system to the object based on the comparison of the difference between the detected reference amplitude voltage and the detected amplitude of the composite signal voltage with a specified threshold reference level.