Loop antenna

• US 10,680,333 B2
• Filed: 03/07/2016
• Issued: 06/09/2020
• Est. Priority Date: 03/18/2015
• Status: Active Grant

• Current Assignee: Nippon Telegraph and Telephone Corporation
• Original Assignee: Nippon Telegraph and Telephone Corporation
• Inventors: Sasaki, Ai-ichiro, Mizota, Tsutomu, Morimura, Hiroki, Kagami, Osamu
• Primary Examiner(s): Tran, Hai V
• Assistant Examiner(s): Jegede, Bamidele A
• Application Number:
  US15/542,338
• Publication Number:
  US 20180277953A1
• Time in Patent Office: 1,555 Days
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• 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

Provided is a loop antenna which can contribute to an increase of an area of a radio system using a magnetic field. The loop antenna includes a main loop 1 which is an open loop connected to a signal source 5 or a reception circuit; and an amplification loop 2 which is a closed loop having the same shape as the main loop 1. The main loop 1 and the amplification loop 2 are arranged on a same surface of a flat substrate formed of an insulator. A first capacitance is connected to the main loop 1, and a second capacitance is connected to the amplification loop.

Claims

1. A loop antenna comprising:

a main loop which is an open loop connected to a signal source, wherein an internal resistance is connected to the signal source; and

an amplification loop which is a closed loop having a same shape as the main loop, wherein

the main loop and the amplification loop are electrically unconnected and are arranged on a same surface of a flat substrate formed of an insulator,

a first capacitance and a first resistance are connected to the main loop in series,

a second capacitance and a second resistance are connected to the closed loop of the amplification loop in series, and

the second resistance is smaller than a sum of the first resistance and the internal resistance.

2. The loop antenna according to claim 1, wherein a distance between the main loop and the amplification loop is equal to or smaller than one-tenth of a square root of an area of a region surrounded by the main loop or the amplification loop.

3. The loop antenna according to claim 1, wherein the number of turns in the main loop is equal to the number of turns in the amplification loop.

4. The loop antenna according to claim 1, wherein

the main loop is connected to the signal source, and

when self-inductance of the main loop is equal to self-inductance of the amplification loop, the first capacitance C1 of the main loop and the second capacitance C2 of the amplification loop satisfy the following formulae:

8. The loop antenna according to claim 2, wherein

the main loop is connected to the signal source, and

when self-inductance of the main loop is equal to self-inductance of the amplification loop, the first capacitance C1 of the main loop and the second capacitance C2 of the amplification loop satisfy the following formulae:

5. A loop antenna comprising:

a main loop which is an open loop connected to a signal source or a reception circuit; and

an amplification loop which is a closed loop having a same shape as the main loop, wherein

the main loop and the amplification loop are electrically unconnected and are arranged on different surfaces of a flat substrate formed of an insulator or on different flat substrates in a structure in which a plurality of flat substrates are stacked one on top of another,

a first capacitance and a first resistance are connected to the main loop in series, and

a second capacitance and a second resistance are connected to the closed loop of the amplification loop in series.

6. The loop antenna according to claim 5, wherein a distance between the main loop and the amplification loop is equal to or smaller than one-tenth of a square root of an area of a region surrounded by the main loop or the amplification loop.

7. The loop antenna according to claim 5, wherein the number of turns in the main loop is equal to the number of turns in the amplification loop.

9. The loop antenna according to claim 5, wherein

the main loop is connected to the signal source,

an internal resistance is connected to the signal source, and

the second resistance is smaller than a sum of the first resistance and the internal resistance.