Detector and modulator circuits for passive microwave links

• US 5,598,169 A
• Filed: 03/24/1995
• Issued: 01/28/1997
• Est. Priority Date: 03/24/1995
• Status: Expired due to Term

• Current Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Drabeck, Lawrence M., Tran, Cuong, Schneider, Martin V.
• Primary Examiner(s): Le, Hoanganh T.
• Application Number:
  US08/409,782
• Time in Patent Office: 676 Days
• Field of Search: 343/701, 343/702, 343/700 MS, 343/793, 343/795, 455/280, 455/281
• US Class Current: 343/701
• CPC Class Codes: G01S 13/75 using transponders powered from received waves, e.g. using passive transponders , or using passive reflectors
• CPC Class Codes: G01S 13/767 Responders; Transponders teaching or practice apparatus for gun-aiming or gun-laying using reflecting targets or active targets F41G3/26
• CPC Class Codes: G01V 15/00 Tags attached to, or associated with, an object, in order to enable detection of the object record carriers for use with machines having a detectable tag or marker G06K19/00
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs

Abstract

An RF apparatus (e.g., a wireless label) provides improved backscattering of an incident RF signal by utilizing a separate modulator diode, which connects across the antenna, to modulate the backscattering of the antenna. A separate detector diode connects across the antenna through an impedance matching network to detect modulated signals received by the antenna.

Claims

1. An RF apparatus, comprising

an antenna,

a detector diode connected across the antenna to detect modulated signals received by the antenna, said detector diode connecting to the antenna through a matching network such that an impedance of the detector diode at a predetermined RF frequency conjugately matches an antenna port impedance transformed through the matching network, and

a modulator diode connected across the antenna to modulate backscattering of the antenna.

2. The apparatus of claim 1 wherein the antenna is a folded monopole.

3. The apparatus of claim 1 wherein the antenna is a dipole.

4. The apparatus of claim 3 wherein the dipole antenna is a half-wavelength long and the antenna port impedance is real.

5. The apparatus of claim 1 wherein the modulator diode is a tunnel diode.

6. The apparatus of claim 5 wherein the tunnel diode is biased off during the time when the apparatus is in a receiving mode.

7. The apparatus of claim 5 wherein the tunnel diode is biased in a negative resistance portion of its forward-biased region during the time when the apparatus is in a backscatter mode.

8. The apparatus of claim 5 wherein the tunnel diode is biased substantially at a valley voltage of its forward-biased region during the time when the apparatus is in the receiving mode.

9. The apparatus of claim 1 wherein

the detector and modulator diodes connect across the antenna in different directions.

10. The apparatus of claim 1 wherein

a detector circuit connects across the detector diode through a transmission circuit which provides an essentially open circuit impedance across the detector diode at the predetermined frequency.

11. The apparatus of claim 10 wherein the transmission circuit includes a quarter-wavelength transmission line connected between the detector diode and a capacitor at an input of a connected detector circuit.

12. The apparatus of claim 1 wherein a modulator circuit connects across the modulator diode through a transmission circuit including a quarter-wavelength transmission line connected across the modulator diode and a capacitor at an input of a connected modulation circuit.

13. The apparatus of claim 1 wherein the detector diode is a Schottky detector diode.

14. An RF apparatus for operating in at least a receiving mode and a backscattering mode, the apparatus comprising:

an antenna for receiving an RF signal, the antenna having an antenna port impedance;

a detector circuit for detecting the RF signal during the receiving mode of the apparatus, the detector circuit comprising,

a matching network, and

a detector diode connected across the antenna through the matching network such that an impedance of the detector diode at a predetermined RF frequency conjugately matches the antenna port impedance transformed through the matching network; and

a modulator circuit for modulating the signal for backscattering during the backscattering mode, the modulator circuit comprising,

a modulator diode connected across the antenna to enhance the backscattering of the antenna, and

a baseband modulator circuit for activating and deactivating the modulator diode to modulate backscattering of the antenna.