Patent US2939195A successfully refreshed from Google Patents.
US5771021A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Transponder employing modulated backscatter microstrip double patch antenna
Assignee: TC Bermuda Finance Ltd
•
Filing: 1995-10-31
•
Granted: 1998-06-23
•
Expires: 2015-10-31
Abstract
Abstract A reader interrogates a transponder attached to a remote object. The transponder includes a microstrip patch antenna having two segments connected together by a switch, each segment being one-half wavelength, the antenna being a full wavelength at the frequency of the interrogating signal. In response to a control signal, the switch is opened and closed, thereby coupling and decoupling the two segments of the microstrip antenna. When the switch is in the closed position, the two segments are out-of-phase with one another, thereby producing a maximum reflected signal. When the switch is in the open position, the two segments act in concert to produce a minimum backscattered signal. The backscatter signal is thus modulated in accordance with the control signal and is received at the reader where it is subsequently decoded to identify the remote object.
Inventors
- 👤 Richard L. Veghte
- 👤 Curtis L. Carrender
- 👤 Alfred R. Koelle
- 👤 Jeremy A. Landt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 10:24
CPC Classifications
G; G06; G06K; G06K19/00; G06K19/06; G06K19/067; G06K19/07; G06K19/077; G06K19/07749; G06K19/07773; G06K19/07786; G01; G01S; G01S13/00; G01S13/74; G01S13/75; G01S13/751; G01S13/756; G06K19/0723; G06K7/00; G06K7/0008; G06K7/10; G06K7/10009; G06K7/10316; G06K7/10346; H; H01; H01Q; H01Q1/00; H01Q1/12; H01Q1/22; H01Q1/24; H01Q1/247; H01Q1/27; H01Q1/32; H01Q1/3208; H01Q1/3233; H01Q1/36; H01Q1/38; H01Q21/00; H01Q21/29; H01Q21/293; H01Q3/00; H01Q3/44; H01Q3/46; H01Q9/00; H01Q9/04; H01Q9/0407; H01Q9/0442
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
208 words
A system including a reader and a transponder displaced from the reader for identifying an object associated with the transponder, said system comprising: interrogating means at the reader for transmitting interrogating signals at an RF frequency to the transponder; a microstrip patch antenna at the transponder for receiving the interrogating signals and for transmitting backscatter-modulated signals in response to the interrogating signals in accordance with a modulating signal produced by modulating means at the transponder, the modulating signal identifying the object associated with the transponder, the antenna comprising two one-half wavelength segments, at least one of which has an input line for receiving an external signal, connected together by a switch having a closed position and an open position, the antenna being full wavelength at the RF frequency, the two segments of the antenna being out-of-phase with each other when the switch is in the closed position, whereby a backscatter signal is reflected back to the reader, and the two segments of the antenna acting in concert when the switch is in the open position, whereby a minimum backscatter signal is reflected back to the reader; and a switching circuit for actuating the switch between the open position and the closed position in response to the external signal.
Claim 2
Independent Claim
208 words
A system including a reader and a transponder displaced from the reader for identifying an object associated with the transponder, said system comprising: interrogating means at the reader for transmitting interrogating signals at an RF frequency to the transponder; a microstrip patch antenna at the transponder for receiving the interrogating signals and for transmitting backscatter-modulated signals in response to the interrogating signals in accordance with a modulating signal produced by modulating means at the transponder, the modulating signal identifying the object associated with the transponder, the antenna comprising two one-half wavelength segments, at least one of which has an input line for receiving an external signal, connected together by a switch having a closed position and an open position, the antenna being full wavelength at the RF frequency, the two segments of the antenna being out-of-phase with each other when the switch is in the closed position, whereby a backscatter signal is reflected back to the reader, and the two segments of the antenna acting in concert when the switch is in the open position, whereby a minimum backscatter signal is reflected back to the reader; and a switching circuit for actuating the switch between the open position and the closed position in response to the external signal.
Claim 3
Dependent Claim
14 words
A system according to claim 1 wherein each of the segments has linear polarization.
Claim 4
Dependent Claim
14 words
A system according to claim 1 wherein each of the segments has circular polarization.
Claim 5
Independent Claim
223 words
A method of identifying a remote object using an interrogator and a transponder located at the remote object comprising the steps of: transmitting an interrogating signal from the interrogator, the interrogating signal being at an RF frequency; receiving the interrogating signal at the transponder, the transponder comprising a microstrip patch antenna, the microstrip patch antenna comprising two one-half wavelength segments, at least one of which has an input line for receiving an external control signal associated with the remote object, connected together by a switch having a closed position and an open position, the microstrip patch antenna being full wavelength at the RF frequency; responding to the interrogating signal via a backscatter-modulated signal produced by the microstrip patch antenna, wherein when the switch is in the closed position, the two segments of the microstrip patch antenna are out-of-phase with each other, thereby producing a backscatter signal as seen by the reader, and when the switch is in the open position the two segments of the microstrip patch antenna act in concert, whereby a minimum backscatter signal is produced, the switch being opened and closed by a switching circuit in response to the external control signal associated with the remote object; and receiving the backscatter-modulated signal at the reader and demodulating the backscatter-modulated signal to produce an identifying signal associated with the remote object.
Claim 6
Independent Claim
223 words
A method of identifying a remote object using an interrogator and a transponder located at the remote object comprising the steps of: transmitting an interrogating signal from the interrogator, the interrogating signal being at an RF frequency; receiving the interrogating signal at the transponder, the transponder comprising a microstrip patch antenna, the microstrip patch antenna comprising two one-half wavelength segments, at least one of which has an input line for receiving an external control signal associated with the remote object, connected together by a switch having a closed position and an open position, the microstrip patch antenna being full wavelength at the RF frequency; responding to the interrogating signal via a backscatter-modulated signal produced by the microstrip patch antenna, wherein when the switch is in the closed position, the two segments of the microstrip patch antenna are out-of-phase with each other, thereby producing a backscatter signal as seen by the reader, and when the switch is in the open position the two segments of the microstrip patch antenna act in concert, whereby a minimum backscatter signal is produced, the switch being opened and closed by a switching circuit in response to the external control signal associated with the remote object; and receiving the backscatter-modulated signal at the reader and demodulating the backscatter-modulated signal to produce an identifying signal associated with the remote object.
Claim 7
Dependent Claim
198 words
A transponder comprising: a modulator generating a control signal; and a patch antenna coupled to the modulator for emitting backscatter-modulated signals at a fundamental frequency in response to a received signal, the patch antenna comprising two one-half wavelength segments, at least one of which has an input line for receiving an external signal, connected together by a switch having a closed position and an open position, the antenna being full wavelength at the fundamental frequency, the two segments being out-of-phase with each other when the switch is in the closed position, whereby a backscatter signal is emitted in response to the received signal, and the two segments of the antenna acting in concert when the switch is in the open position, whereby a minimum backscatter signal is emitted in response to the received signal, and the two segments of the antenna acting in concert when the switch is in the open position, whereby a minimum backscatter signal is produced in response to the received signal; a switching circuit for actuating the switch between the open position and the closed position in response to the external signal; wherein the switch opens and closes in response to the control signal.
Claim 8
Dependent Claim
198 words
A transponder comprising: a modulator generating a control signal; and a patch antenna coupled to the modulator for emitting backscatter-modulated signals at a fundamental frequency in response to a received signal, the patch antenna comprising two one-half wavelength segments, at least one of which has an input line for receiving an external signal, connected together by a switch having a closed position and an open position, the antenna being full wavelength at the fundamental frequency, the two segments being out-of-phase with each other when the switch is in the closed position, whereby a backscatter signal is emitted in response to the received signal, and the two segments of the antenna acting in concert when the switch is in the open position, whereby a minimum backscatter signal is emitted in response to the received signal, and the two segments of the antenna acting in concert when the switch is in the open position, whereby a minimum backscatter signal is produced in response to the received signal; a switching circuit for actuating the switch between the open position and the closed position in response to the external signal; wherein the switch opens and closes in response to the control signal.
References Cited (Backward Citations)
US4786907A
Cited
US5119099A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-06-22 | 2001-12-22 | 2002-06-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-06-22 | 2005-12-22 | 2006-06-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-06-22 | 2009-12-22 | 2010-06-23 | $7700.00 | Window Closed / Lapsed |