Wire antenna with optimized impedance for connecting to a circuit
First Claim
1. An antenna for use as a power source with a load having a complex impedance comprising:
- a. an antenna section that has one or more elements and one or more antenna terminals, the antenna tuned to receive a radio frequency signal having a wavelength, an impedance across the antenna terminals having a real and a reactive part; and
b. one or more loading bars, each loading bar having an effective length, the loading bar being within an antenna distance of at least one of the elements of the antenna over the effective length, the antenna distance being less than one quarter of the wavelength, and the loading bar reducing the real part of the impedance such that power delivered to the load by the antenna is increased.
3 Assignments
0 Petitions
Accused Products
Abstract
An antenna used as a voltage and power source is designed to operate with arbitrary load, or front end. The antenna has one or more (number of) loading bars that are placed adjacent to the elements of the antenna at a spacing distance. The real part of the antenna input impedance is changed by adjusting the loading bar length, width, and/or spacing distance and/or the number of loading bars. These changes are implemented to reduce the real part of the antenna input impedance to make it small enough to develop an adequate voltage, Vp, to operated the front end and connected circuitry. In a preferred embodiment, the real part of the antenna input impedance is reduced to the point at which Vp no longer increases. One or more stubs is added to one or more of the antenna elements. The stubs act as two-conductor transmission line and is terminated either in a short-circuit or open-circuit. The short-circuit stubs act as a lumped inductor. The open-circuit stub acts as a lumped capacitor. The magnitude of these lumped capacitors and inductors (reactances) is affected by a stub length, a stub conductor width, and a stub spacing. Zero or more short-circuit stubs and zero or more open-circuit stubs are added to one or more of the antenna elements to change the reactive (imaginary) part of the antenna input impedance. In a preferred embodiment, the reactive part is changed to be equal to the negative magnitude of the reactive part of the front end input impedance. For a given real part of the antenna impedance, Ra, this approach maximizes both the DC voltage generated from the input and maximizes the power transferred between the antenna and the front end.
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Citations
26 Claims
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1. An antenna for use as a power source with a load having a complex impedance comprising:
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a. an antenna section that has one or more elements and one or more antenna terminals, the antenna tuned to receive a radio frequency signal having a wavelength, an impedance across the antenna terminals having a real and a reactive part; and b. one or more loading bars, each loading bar having an effective length, the loading bar being within an antenna distance of at least one of the elements of the antenna over the effective length, the antenna distance being less than one quarter of the wavelength, and the loading bar reducing the real part of the impedance such that power delivered to the load by the antenna is increased. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An antenna for use as a power source with a load having a complex impedance comprising:
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a. an antenna section that has one or more elements and one or more antenna terminals, the antenna tuned to receive a radio frequency signal having a wavelength, an impedance across the antenna terminals having a real and a reactive part; b. one or more loading bars, each loading bar having an effective length, the loading bar being within an antenna distance of at least one of the elements of the antenna over the effective length, the antenna distance being less than one quarter of the wavelength, and the loading bar reducing the real part of the impedance such that power delivered to the load by the antenna is increased; and c. one or more tuning stubs in one or more of the elements, each of the stubs being a transmission line with a guided wavelength related to the wavelength, and each of the stubs having two conductors each with a conductor width, a stub length, a stub spacing between the conductors, and a termination, each of the stubs contributing a reactance to the reactive part. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. An antenna for use as a power source with a load having a complex impedance comprising:
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a. an antenna section means, that has one or more elements and two or more antenna terminals, for being tuned to receive a radio frequency signal having a wavelength, an impedance across the antenna terminals having a real and a reactive part; and b. one or more loading bars for reducing the real part of the impedance such that pover delivered to the load by the antenna is increased, each loading bar having an effective length, the loading bar being within an antenna distance to at least one of the elements of the antenna over the effective length, the antenna distance being less than one quarter of the wavelength.
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26. A radio frequency tag having an antenna with one or more antenna terminals, for use as a power source with a front end having a complex impedance the antenna terminals electrically connected to a front end, and the front end electrically connected to a tag circuit, the antenna further comprising:
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a. an antenna section that has one or more elements connected to terminals, the antenna tuned to receive a radio frequency signal having a wavelength, an impedance across the antenna terminals having a real and reactive part; and b. one or more loading bars, each loading bar having an effective length, the loading bar being within an antenna distance to at least one of the elements of the antenna over the effective length, the antenna distance being less than one quarter of the wavelength, and the loading bar reducing the real part of the impedance such that power delivered to the front end by the antenna is increased.
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Specification