Wide-band loop antenna with outer and inner loop conductors

• US 5,198,826 A
• Filed: 09/13/1990
• Issued: 03/30/1993
• Est. Priority Date: 09/22/1989
• Status: Expired due to Fees

• Current Assignee: Nippon Sheet Glass Company Limited (Nippon Telegraph and Telephone Corporation)
• Original Assignee: Nippon Sheet Glass Company Limited (Nippon Telegraph and Telephone Corporation)
• Inventors: Ito, Michiaki
• Primary Examiner(s): Wimer, Michael C.
• Application Number:
  US07/581,893
• Time in Patent Office: 929 Days
• Field of Search: 343/713, 343/730, 343/726, 343/742, 343/728, 343/843, 343/833, 343/834, 343/873
• US Class Current: 343/726
• 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

A wide-band loop antenna consists of a main loop antenna conductor and a sub-loop antenna conductor. The main loop antenna conductor is provided on a dielectric plate to extend from one terminal of a pair of feed terminals to another one of the terminals so as to form a one-turn open loop. The loop antenna conductor is provided on the dielectric plate so as to extend along the main antenna conductor to provide a one-turn open loop and is connected to the pair of feed terminals to constitute a synthesized antenna together with the main antenna conductor. Short-circuting conductors are provided to connect the main antenna conductor with the sub-antenna conductor for shifting a resonance frequency of the synthesized antenna outside the operating band to obtain a wide-band frequency characteristic. In a modification, the sub-antenna conductor forms a closed loop serving as a parasitic antenna which improves an impedance characteristic of the main antenna conductor.

Claims

1. A wide-band loop antenna comprising:

a main loop conductor provided on a dielectric plate and extending from a first feed terminal to a second feed terminal to form a one-turn loop;

a subsidiary loop conductor provided on the dielectric plate and extending parallel to the main loop conductor to form a one-turn loop, said main and subsidiary loop conductors being connected to said feed terminals to provide a closed circuit;

a first short-circuit line connected between said main and subsidiary loop conductors at a position adjacent said first feed terminal; and

a dipole antenna connected to said feed terminals.

2. A wide-band loop antenna according to claim 1, wherein said closed circuit has an inherent resonance frequency and said dipole antenna has a resonance frequency that is not a multiple of said closed circuit inherent resonance frequency.

3. A wide-band loop antenna comprising:

a main loop conductor provided on a dielectric plate and extending from a first feed terminal to a second feed terminal to form a one-turn loop;

a subsidiary loop conductor provided on the dielectric plate and extending parallel to the main loop conductor to form a one-turn loop, said main and subsidiary loop conductors being connected to said feed terminals to provide a closed circuit;

a first short-circuit line connected between said main and subsidiary loop conductors at a position adjacent said first feed terminal; and

an antenna conductor not formed into a loop, said antenna conductor not formed into a loop being connected to said feed terminals, wherein said antenna conductor not formed into a loop is disposed substantially in the plane of and unencompassed by the loops formed by said main and subsidiary loop conductors.

4. A wide-band loop antenna comprising:

a main loop conductor provided on a dielectric plate and extending from one feed terminal to another feed terminal to form a one-turn loop;

a first parasitic closed loop conductor arranged substantially in the plane of and encompassed by said main loop conductor, said first parasitic closed loop extending parallel to and concentric with said main loop conductor and having a distance therebetween less than 1/100 of a wavelength of a transmission/reception wave;

a second loop conductor arranged substantially in the plane of and encompassed by said main loop conductor and having two ends, said ends being connected to the feed terminals, and

a second parasitic closed loop conductor arranged substantially in the plane of and encompassed by said second loop conductor, said second parasitic closed loop conductor extending parallel to and concentric with said second loop conductor and having a distance therebetween less than 1/100 of said wavelength.

5. A wide-band loop antenna according to claim 4, further comprising a short-circuit line connected between said main and second loop conductors at a position adjacent to said feed terminals.

6. A wide-band loop antenna according to claim 5, wherein at least a pair of short-circuit lines is provided at respective points located at equal distances from said feed terminals.