Portable multi-antenna signal receiver

• US 6,636,728 B1
• Filed: 04/06/2000
• Issued: 10/21/2003
• Est. Priority Date: 04/07/1999
• Status: Expired due to Fees

• Current Assignee: Valeo Securite Habitacle (Valeo SE)
• Original Assignee: Valeo Securite Habitacle (Valeo SE)
• Inventors: Avenel, Jean-Jacques
• Primary Examiner(s): Maung, Nay
• Assistant Examiner(s): LELE, TANMAY S
• Application Number:
  US09/544,138
• Time in Patent Office: 1,293 Days
• Field of Search: 455/90, 455/101, 455/102, 455/277.1, 455/277.2, 455/562, 455/274, 343/700.R, 343/702, 343/729, 343/713, 343/788, 343/742, 375/258
• US Class Current: 455/277.1
• CPC Class Codes: H04B 5/22 Capacitive coupling
• CPC Class Codes: H04B 5/26 using coils
• CPC Class Codes: H04B 7/08 at the receiving station
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity

Abstract

A portable receiver comprised of several antennas that are connected to a receiver unit for receiving a signal transmitted by an electromagnetic induction process. The antennas are made in the form of coils, that are carried by a support in such a way that the respective turns of the coils are oriented along different respective axes of an axis system associated with the support. The invention further includes a phase shifting means oriented between the antennas and the receiver unit. The phase shifting means is designed to produce a temporal phase shift corresponding to an angle of (n−1)π/n, at the frequency of the signal received between induced signals delivered by the antennas (n being the number of antennas).

Claims

1. A portable receiver comprising several antennas (3, 4) which are connected to a receiver unit (5) for receiving a signal transmitted by electromagnetic induction, said antennas being made in the form of coils (L1, L2) which are carried by a support (2) in such a way that the respective turns of said coils are oriented along different respective axes (9, 11) of a reference axis system associated with said support (2), as well as phase-shifting means (15) placed between said antennas (3, 4) and said receiver unit (5), wherein said phase-shifting means (15) are designed to produce, between the induced signals delivered by said antennas (3, 4) respectively, a temporal phase shift corresponding to an angle of (n−

1)π

/n at the frequency of the signal to be received, n being the number of antennas.

2. The receiver as claimed in claim 1, which comprises two antennas (3, 4), the coils (L1, L2) of which have their respective turns oriented at 90°

to each other, wherein a first (3) of the two antennas is connected to a first phase-shifter circuit (15a) which phase-shifts the induced signal delivered by the first antenna (3) by +45°

, while the second antenna (4) is connected to a second phase-shifter circuit (15b) which phase-shifts the induced signal delivered by the second antenna by −

45°

.

3. The receiver as claimed in claim 2, wherein the first phase-shifter circuit (15a) comprises a first capacitor (C12), a first plate of which is electrically connected to the output of the first antenna (3), and a first resistor (R1), the ends of which are electrically connected to a second plate of the first capacitor (C12) and to ground respectively, the junction between the second plate of the first capacitor (C12) and the corresponding end of the first resistor (R1) being connected to a first output terminal (16).

4. The receiver as claimed in claim 3, wherein the second phase-shifter circuit (15b) comprises a second resistor (R2), a first end of which is electrically connected to the output of the second antenna (4), and a second capacitor (C22), the plates of which are electrically connected to a second end of the second resistor (R2) and to ground respectively, the junction between the second end of the second resistor (R2) and the corresponding plate of the second capacitor (C22) being connected to a second output terminal (17).

5. The receiver as claimed in claim 1, which comprises two antennas (3, 4), the coils (L1, L2) of which have their respective turns oriented at 90°

to each other, wherein a first (3) of the two antennas is electrically connected directly to a first output terminal (16), while the second antenna (4) is connected to a second output terminal (17) via a phase-shifter circuit (15) which phase-shifts the induced signal delivered by the second antenna (4) by 90°

.

6. The receiver as claimed in claim 5, wherein said phase-shifter circuit (15) is a delay line designed to introduce a delay (Δ

t) of ¼

f, f being the frequency of the signal to be received.

7. The receiver as claimed in claim 1, which comprises three antennas (3, 4, 13), the coils (L1, L2, L3) of which have their respective turns oriented in directions (9, 11, 14) which are perpendicular to one another in pairs, wherein said temporal phase-shifting means (15) produces a phase shift of 120°

between the three induced signals delivered by the three antennas (3, 4, 13) respectively.

8. The receiver as claimed in claim 7, wherein said phase-shifting means (15) comprise delay lines (15A, 15B).

9. The receiver as claimed in claim 8, wherein the coil (L1, L2 or L3) of each antenna (3, 4, or 13) is associated with a capacitor (C1, C2 or C3) which forms with said coil a parallel resonant circuit tuned to the frequency f of the signal to be received.

10. The receiver as claimed in claim 9, as it depends on claim 8, wherein a first parallel resonant circuit (L1, C1) formed with the coil (L1) of a first (3) of the three antennas (3, 4, 13) has a first end which is electrically connected to a first output terminal (16) and a second end which is electrically connected to a first of the two ends of a second parallel resonant circuit (L2, C2) formed with the coil (L2) of a second (4) of the three antennas, wherein the second end of the second parallel resonant circuit (L2, C2) is connected via a first delay line (15A) to a first of the two ends of a third parallel resonant circuit (L3, C3) which is formed with the coil (L3) of the third antenna (13) and the second end of which is connected via a second delay line (15B) to a second output terminal (17), and wherein the first and second delay lines (15A and 15B) are designed to introduce a delay (Δ

t₁) of ⅓

f and a delay (Δ

t₂) of ⅔

f respectively, f being the frequency of the signal to be received.

11. The receiver as claimed in claim 10, wherein the first and second output terminals (16 and 17) are electrically connected to the inputs of a differential amplifier (18), the output (19) of which is electrically connected to said receiver unit (5).