Antenna and miniature portable wireless transceiver

• US 5,673,054 A
• Filed: 08/31/1994
• Issued: 09/30/1997
• Est. Priority Date: 05/09/1991
• Status: Expired due to Fees

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Hama, Norio
• Primary Examiner(s): Hajec, Donald T.
• Assistant Examiner(s): PHAN, THO GIA
• Application Number:
  US08/299,335
• Time in Patent Office: 1,126 Days
• Field of Search: 343/744, 343/702, 343/748, 343/745, 343/866, 343/718
• US Class Current: 343/744
• CPC Class Codes: H01Q 1/273 Adaptation for carrying or wearing by persons or animals
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop

Abstract

A loop antenna device of the invention, when incorporated in a transceiver, stably a high level of sensitivity without being substantially influenced by the body, regardless of the posture or direction of the transceiver when the transceiver is mounted on or carried by the human body. The loop antenna device also provides, when the transceiver is not carried on a human body, a highly stable sensitivity characteristic even in such a condition that the polarization plane changes over time under the influence of multi-path strain or fading. The antenna circuit which provides these advantageous effects does not require any additional element for matching and contributes to reduction in the size of a transceiver.

Claims

1. A loop antenna device for use in a portable apparatus having said loop antenna device, at least one of a transmission circuit and a receiving circuit, a data decoder, a CPU, a data display means and an informing circuit, said portable apparatus having a horizontal position and a vertical position, said loop antenna device comprising:

a first loop portion having a first terminal connected to a first variable capacitance means and a second terminal connected to a first terminal of a second variable capacitance means; and

a second loop portion forming a loop antenna with the first loop portion, said loop antenna detecting a magnetic field component of an electromagnetic wave, said second loop portion having a first terminal connected to a second terminal of said second variable capacitance means and a second terminal connected to a high-frequency grounded surface, said high-frequency grounded surface having a rectangular form, a plane of the loop antenna being substantially parallel to a shorter side of said high-frequency grounded surface and substantially perpendicular to a longer side of said high-frequency grounded surface, said grounded surface detecting the electric field component of the electromagnetic wave, said first loop portion and said second loop portion being spaced away from said grounded surface between the first and second terminals of said first and second loop portions, wherein when said portable apparatus is in the horizontal position, a ratio of a capacitance of the second variable capacitance means to a capacitance of said first variable capacitance means is substantially equal to a ratio of a length of said first loop portion to a length of said second loop portion of said loop antenna.

2. A loop antenna device according to claim 1, wherein each of said first and second variable capacitance means is adapted to change its capacitance as a result of application of a voltage across said variable capacitance means, said loop antenna device further comprising means for applying a voltage across said variable capacitance means.

3. A loop antenna device according to claim 2, wherein said means for applying a voltage varies said voltage in accordance with a posture of said portable apparatus.

4. A loop antenna device according to claim 3, wherein said means for applying a voltage includes a switch which changes said voltage in accordance with the posture of said portable apparatus.

5. The loop antenna device according to claim 3, wherein the means for applying voltage increases a voltage applied to the second capacitance means and decreases a voltage applied to the first capacitance means when the antenna device is changed from the horizontal to the vertical position.

6. The loop antenna device according to claim 1, wherein the portable apparatus is a receiver.

7. The loop antenna device according to claim 1, wherein the portable apparatus is a transmitter.

8. The loop antenna device according to claim 1, wherein the portable apparatus is a transceiver.

9. A portable apparatus having a loop antenna device, said portable apparatus having a horizontal position and a vertical position, said loop antenna device comprising:

a first loop portion having a first terminal connected to a first variable capacitance means and a second terminal connected to a first terminal of a second variable capacitance means; and

a second loop portion forming a loop antenna with the first loop portion, said loop antenna detecting a magnetic field component of an electromagnetic wave, said second loop portion having a first terminal connected to a second terminal of said second variable capacitance means and a second terminal connected to a high-frequency grounded surface, said high-frequency grounded surface having a rectangular form, a plane of the loop antenna being substantially parallel to a shorter side of said high-frequency grounded surface and substantially perpendicular to a longer side of said high-frequency grounded surface, said high-frequency grounded surface detecting the electric field component of the electromagnetic wave, said first loop portion and said second loop portion being spaced away from said grounded surface between the first and second terminals of said first and second loop portions, wherein when said portable apparatus is in the horizontal position, a ratio of a capacitance of the second variable capacitance means to a capacitance of said first variable capacitance means is substantially equal to a ratio of a length of said first loop portion to a length of said second loop portion of said loop antenna.

10. The portable apparatus according to claim 9, wherein the portable apparatus is a transceiver.

11. The portable apparatus according to claim 9, wherein the portable apparatus is a receiver.

12. The portable apparatus according to claim 9, wherein the portable apparatus is a transmitter.

13. A loop antenna device for use in a portable apparatus having said loop antenna device, at least one of a transmission circuit and a receiving circuit, a data decoder, a CPU, a data display means and an informing circuit which are encased in a casing, said loop antenna device comprising:

a board being substantially rectangular having a width and a length, and having an inner printed pattern spreading over substantially an entire area of said board and mounting a circuit for operating said portable apparatus, the length of said board ranging between approximately 1/10 and approximately 1/6 a wavelength of a wave, said wave being at least one of a transmitted wave and a received wave, said board capable of detecting a component of the wave; and

a loop antenna having a first terminal and a second terminal mounted on said board, a plane of said loop antenna being substantially parallel to the width of the said board and substantially perpendicular to said length of said board, said loop antenna having a length between said first and second terminals ranging between approximately 1/10 and approximately 1/6 the wavelength of the wave.

14. A loop antenna device according to claim 13, wherein said loop antenna is divided at a position which is between 6:

1 and 8;

1 of an overall length of said loop antenna into a first loop portion having a greater length than a second loop portion, said first loop portion being connected at a first terminal to a common potential pattern of said portable apparatus and at a second terminal to a first terminal of said second loop portion through a capacitive reactance means.

15. A loop antenna device according to claim 14, wherein the length of said board is nearly equal to the sum of lengths of said first loop portion and said second loop portion.

16. A loop antenna device according to claim 13, wherein said loop antenna has a length substantially equal to the length of said board.

17. A portable apparatus having a loop antenna device, said loop antenna device comprising:

a board, said board being substantially rectangular, having a width and a length, having an inner printed pattern spreading over substantially an entire area of said board, and mounting a circuit for operating said portable apparatus, the length of said board ranging between approximately 1/10 and approximately 1/6 a wavelength of a wave, the wave being at least one of a transmitted wave and a received wave, said board capable of detecting a component of the wave; and

a loop antenna having a first terminal and a second terminal mounted on said board, a plane of said loop antenna being substantially parallel to the width of said board and substantially perpendicular to said length of said board, said loop antenna having a length between said first and second terminals ranging between approximately 1/10 and approximately 1/6 the wavelength of the wave, wherein said loop antenna length is nearly equal to the length of said board.

18. The portable apparatus according to claim 17, wherein the portable apparatus is a transceiver.

19. The portable apparatus according to claim 17, wherein the portable apparatus is a receiver.

20. The portable apparatus according to claim 17, wherein the portable apparatus is a transmitter.

21. A portable apparatus having a loop antenna device, said loop antenna device comprising:

a board, said board being substantially rectangular, having a width and a length, having an inner printed pattern spreading over substantially an entire area of said board, and mounting a circuit for operating said portable apparatus, the length of said board ranging between approximately 1/10 and approximately 1/6 a wavelength of a wave, the wave being at least one of a transmitted wave and a received wave, said board capable of detecting a component of the wave; and

a loop antenna having a first loop terminal and a second loop terminal mounted on said board, a plane of said loop antenna being substantially parallel to the width of said board and substantially perpendicular to said length of said board, said loop antenna having a length between said first and second loop terminals ranging between approximately 1/10 and approximately 1/6 the wavelength of the wave, said loop antenna being divided at a position which is between 6;

1 and 8;

1 of an overall length of said loop antenna into a first loop portion having a greater length than a second loop portion, said first loop portion being connected at first loop terminal to a common potential pattern of said portable apparatus through a first capacitive reactance element and at a second terminal to a first terminal of said second loop portion through a second capacitive reactance element, and wherein the length of said board is substantially equal to the sum of a length of said first loop portion between said first loop terminal and said second terminal and a length of said second loop portion between said first terminal of said second loop portion and said second loop portion.

22. The portable apparatus according to claim 21, wherein the portable apparatus is a transceiver.

23. The portable apparatus according to claim 21, wherein the portable apparatus is a receiver.

24. The portable apparatus according to claim 21, wherein the portable apparatus is a transmitter.

25. A loop antenna device for use in a portable apparatus having a loop antenna device and a wireless circuit, wherein said loop antenna device includes a loop antenna having a longitudinal slit that forms a first conductor plate and a second conductor plate of the loop antenna, said longitudinal slit detecting a magnetic field component of a wave that is orthogonal to the magnetic field detected by said loop antenna, said wave being at least one of a transmitted wave and a received wave;

a capacitive reactance means that interconnects first and second points located respectively on the first and second conductor plates, the first and second points opposing each other across the longitudinal slit; and

a feeding point on a portion of one of the first and second conductor plates, said portion located adjacent to the longitudinal slit.

26. A loop antenna device for use in a portable apparatus having said loop antenna device and a wireless circuit, said loop antenna device including:

a loop antenna having a longitudinal slit that forms a first conductor plate and a second conductor plate of the loop antenna, said longitudinal slit detecting a magnetic field component of a wave that is orthogonal to the magnetic field detected by said loop antenna, said wave being at least one of a transmitted wave and a received wave, said first conductor plate being connected to a common potential pattern of the wireless circuit; and

a capacitive reactance means which interconnects first and second points located respectively on the first and second conductor plates, the first and second points opposing each other across the longitudinal slit.

27. A loop antenna device according to claim 26, wherein the second conductor plate is connected to a high-frequency input terminal of said wireless circuit.

28. A loop antenna device according to claim 27, further comprising a second capacitive reactance means attached between first and second ends of said conductor plates.

29. A loop antenna device according to claim 28, wherein the first and second ends of said conductor plates are connected by said second capacitive reactance means to form a plane that is parallel to a plane containing the slit having the second capacitive reactance means, said first and second capacitive reactance means are disposed on said loop antenna device at positions opposite to each other with respect to a center of said longitudinal slit.

30. A miniature portable apparatus having a loop antenna device comprising:

a conductor plate having a longitudinal slit to form a first and second side, said longitudinal slit detecting a magnetic field component of a wave that is orthogonal to the magnetic field detected by said loop antenna device;

a capacitive reactance means which interconnects said first and second side, wherein said first side is connected to a common potential pattern of a wireless circuit, said circuit being at least one of a transmission circuit and a receiving circuit, the second side is connected to a high-frequency input terminal of said wireless circuit; and

a second capacitive reactance means attached between first and second ends of said conductor plate forming a plane parallel to a plane containing the first and second side, and wherein said first and second capacitive reactance means are disposed on said loop antenna device at positions opposite to each other with respect to a center of said slit.

31. The miniature portable apparatus according to claim 30, wherein the portable apparatus is a transceiver.

32. The miniature portable apparatus according to claim 30, wherein the portable apparatus is a receiver.

33. The miniature portable apparatus according to claim 30, wherein the portable apparatus is a transmitter.

34. A portable apparatus having a loop antenna device, said loop antenna device comprising:

a board, said board being substantially rectangular, having an inner printed pattern spreading over substantially an entire area of said board, and mounting a circuit for operating said portable apparatus, said board having a length and a width, said length being longer than said width, said board capable of detecting a component of a wave, said wave being at least one of a received wave and a transmitted wave; and

a loop antenna having a first terminal and a second terminal mounted on said board, a plane of said loop antenna being substantially parallel to said width of said board and substantially perpendicular to said length of said board, a length of said loop antenna between said first and second terminals is substantially equal to the length of said board.

35. A portable apparatus having an antenna device, said antenna device comprising:

a board, said board being substantially rectangular, having an inner printed pattern spreading over substantially an entire area of said board, and mounting a circuit for operating said portable apparatus, said board having a length and a width, said length being longer than said width, said length ranging between approximately 1/10 and approximately 1/6 a wavelength of a wave, said wave being at least one of a transmitted wave and a received wave, said board capable of detecting a component of the wave.

36. A portable apparatus having a loop antenna device, said portable apparatus having a horizontal position and a vertical position, said loop antenna device comprising:

a first loop portion having a first terminal connected to a first capacitor and a second terminal connected to a high-frequency grounded surface, said first loop portion having a first inductance forming a first LC resonance circuit with said first capacitor;

a second loop portion forming a loop antenna with said first loop portion, said second loop portion having a first terminal connected to a second capacitor and a second terminal connected to said first capacitor, said second loop portion having a second inductance forming a second LC resonance circuit with said second capacitor, said first loop portion and said second loop portion being spaced away from said grounded surface between the first and second terminals of said first and second loop portions, said high-frequency grounded surface having a rectangular form, a plane of the loop antenna being substantially parallel to a shorter side of said high-frequency grounded surface and substantially perpendicular to a longer side of said high-frequency grounded surface; and

wherein said high-frequency grounded surface detects at least one of a received wave and a transmitted wave when a value of the first LC resonance circuit is different than a value of the second LC resonance circuit, and when said portable apparatus is in the horizontal position, a ratio of a capacitance of the second variable capacitance means to a capacitance of said first variable capacitance means is substantially equal to a ratio of a length of said first loop portion to a length of said second loop portion of said loop antenna.