Adaptive antenna tuning based on measured antenna impedance
First Claim
1. A system comprising:
- an antenna having a first antenna lead and a second antenna lead;
a directional coupler comprising a first port, a second port, and a third port, wherein the first port is electrically connected to the first antenna lead and the second antenna lead, and wherein the directional coupler directs signals received at the first port to the second and third ports, directs signals received at the second port to the first port, and substantially isolates the second and third ports from each other;
an impedance tuning circuit electrically connected to the second port of the directional coupler, wherein the impedance tuning circuit includes one or more reactive elements;
a test signal measurement circuit electrically connected to the second port of the directional coupler;
a reflected signal measurement circuit electrically connected to the third port of the directional coupler; and
a controller, wherein the controller operates to;
(i) receive, from the test signal measurement circuit, a test-signal measurement of a test signal applied to the antenna through the directional coupler;
(ii) receive from the reflected signal measurement circuit a reflected-signal measurement of a reflected signal reflected from the antenna through the directional coupler in response to the test signal applied to the antenna;
(iii) determine an adjustment to the impedance tuning circuit based on the test-signal measurement and the reflected-signal measurement; and
(iv) cause the impedance tuning circuit to make the determined adjustment.
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Abstract
A system includes an antenna, an impedance measurement circuit, an impedance tuning circuit, and a controller. The impedance measurement circuit can include a test current source that conveys a test current through the antenna, and a voltage sensor that measure a voltage across the antenna while the test current is conveyed through the antenna. The impedance tuning circuit can be coupled to the antenna leads and can include one or more reactive elements that can be selectively coupled to the antenna, or otherwise adjusted, to effect adjustment of the impedance connected to the antenna. The controller can: (i) use the impedance measurement circuit to obtain a measurement indicative of an impedance of the antenna; (ii) determine an adjustment to the impedance tuning circuit based on the obtained measurement; and (iii) cause the impedance tuning circuit to make the determined adjustment.
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Citations
11 Claims
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1. A system comprising:
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an antenna having a first antenna lead and a second antenna lead; a directional coupler comprising a first port, a second port, and a third port, wherein the first port is electrically connected to the first antenna lead and the second antenna lead, and wherein the directional coupler directs signals received at the first port to the second and third ports, directs signals received at the second port to the first port, and substantially isolates the second and third ports from each other; an impedance tuning circuit electrically connected to the second port of the directional coupler, wherein the impedance tuning circuit includes one or more reactive elements; a test signal measurement circuit electrically connected to the second port of the directional coupler; a reflected signal measurement circuit electrically connected to the third port of the directional coupler; and a controller, wherein the controller operates to;
(i) receive, from the test signal measurement circuit, a test-signal measurement of a test signal applied to the antenna through the directional coupler;
(ii) receive from the reflected signal measurement circuit a reflected-signal measurement of a reflected signal reflected from the antenna through the directional coupler in response to the test signal applied to the antenna;
(iii) determine an adjustment to the impedance tuning circuit based on the test-signal measurement and the reflected-signal measurement; and
(iv) cause the impedance tuning circuit to make the determined adjustment. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method comprising:
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measuring, by a test signal measurement circuit, a signal strength of a test signal applied to an antenna, wherein the test signal measurement circuit is electrically coupled between an impedance tuning circuit and a first port of a directional coupler; measuring, by a reflected signal measurement circuit, a signal strength of a reflected signal from the antenna, wherein the reflected signal from the antenna results from the application of the test signal, wherein the reflected signal measurement circuit is electrically coupled to a second port of the directional coupler; determining, based on the signal strength of the test signal applied to the antenna and the signal strength of the reflected signal from the antenna, an adjustment to the impedance tuning circuit, wherein the impedance tuning circuit is electrically connected to the antenna via the directional coupler, and wherein the impedance tuning circuit includes one or more reactive elements; and causing the impedance tuning circuit to make the determined adjustment. - View Dependent Claims (9)
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10. A body-mountable device comprising:
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a polymeric material formed to include a body-mountable surface; a substrate at least partially embedded within the polymeric material; an antenna disposed on the substrate, wherein the antenna has a first antenna lead and a second antenna lead; a directional coupler comprising a first port, a second port, and a third port, wherein the first port is electrically connected to the first antenna lead and the second antenna lead; an impedance tuning circuit disposed on the substrate, wherein the impedance tuning circuit is electrically connected to the second port of the directional coupler, wherein the impedance tuning circuit includes one or more reactive elements; a test signal measurement circuit disposed on the substrate, wherein the test signal measurement circuit is electrically connected to the second port of the directional coupler; a reflected signal measurement circuit disposed on the substrate, wherein the reflected signal measurement circuit is electrically connected to the third port of the directional coupler; and a controller disposed on the substrate, wherein the controller operates to;
(i) receive, from the test signal measurement circuit, a test-signal measurement of a test signal applied to the antenna through the directional coupler;
(ii) receive from the reflected signal measurement circuit a reflected-signal measurement of a reflected signal reflected from the antenna through the directional coupler in response to the test signal applied to the antenna;
(iii) determine an adjustment to the impedance tuning circuit based on the test-signal measurement and the reflected-signal measurement; and
(iv) cause the impedance tuning circuit to make the determined adjustment. - View Dependent Claims (11)
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Specification