Antenna for broadband wireless communications

• US 6,373,448 B1
• Filed: 04/13/2001
• Issued: 04/16/2002
• Est. Priority Date: 04/13/2001
• Status: Expired due to Fees

• Current Assignee: Mobile Mark, Inc.
• Original Assignee: Luxul Corporation (Legrand SA)
• Inventors: Chun, Ki
• Primary Examiner(s): Wimer, Michael C.
• Application Number:
  US09/834,746
• Time in Patent Office: 368 Days
• Field of Search: H01/Q.136, 343/895
• US Class Current: 343/895
• CPC Class Codes: H01Q 1/36 Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewithH01Q1/08, H01Q1/14 take precedence
• CPC Class Codes: H01Q 11/08 Helical antennas

Abstract

A helical antenna includes an elongate core attached to a back plate, and a radiating element in the shape of a helix that rests in a helical groove formed in an exterior major surface of the elongate core. The helical antenna further has an impedance matching section, with a narrow end and a wide end, that is seated in the helical groove at a predetermined distance from the back plate and connected to the radiating element at the narrow end of the impedance matching section.

Claims

1. A circularly polarized helical antenna comprising:

an elongate core formed of a substantially rigid dielectric material having a proximal end, a distal end, an exterior major surface, and a helical groove extending over at least a portion of the exterior major surface;

a radiating element formed of an electrically conductive material and formed into a generally helical shape and positioned generally surrounding the elongate core, the radiating element terminating at a first end positioned adjacent the distal end of the elongate core and at a second end positioned adjacent the proximal end of the elongate core, the radiating element having a first electrical impedance; and

an impedance matching section formed of a substantially rigid, electrically conductive material, the impedance matching section having a narrow end and a wide end, the narrow end being electrically and mechanically connected to the second end of the radiating element, the wide end adapted for connection to an electrical connector, the impedance matching section having a second electrical impedance at the narrow end for matching the first electrical impedance of the radiating element and having a third electrical impedance at the wide end for matching a fourth electrical impedance of the electrical connector, in which the impedance matching section is seated in the helical groove on the elongate core at a point adjacent to the proximal end of the elongate core.

2. The antenna of claim 1, further comprising a back plate attached to the proximal end of the elongate core and in which the wide end of the impedance matching section spaced a predetermined distance from the back plate.

3. The antenna of claim 1 in which the elongate core has a dielectric constant of 3.6.

4. The antenna of claim 3 in which the helical groove includes a pitch angle of between 12 degrees and 13 degrees.

5. The antenna of claim 4 in which:

the elongate core has a length that corresponds to a helix with 7 turns, with a flight spacing ranging from 0.861 inches to 0.871 inches along the length of the elongate core; and

the elongate core has a diameter of between 1.2 and 1.3 inches.

6. The antenna of claim 1 in which the helical groove has a width and the radiating element is formed of a predetermined length of copper wire, the copper wire having a diameter sized less than the width of the helical groove such that the copper wire fits at least partially within the helical groove.

7. The antenna of claim 1 in which the radiating element comprises copper wire and the first electrical impedance is 110 ohms.

8. The antenna of claim 7 in which the impedance matching section is made of copper, the second electrical impedance is 110 ohms, and the third electrical impedance is 50 ohms.

9. The antenna of claim 7 in which the impedance matching section has a thickness between 0.02 and 0.03 inches, an inner radius between 0.620 and 0.630 inches, and an outer radius between 0.745 and 0.755 inches.

11. The antenna of claim 9 in which the elongate core has a dielectric constant of 3.6.

10. A circularly polarized monofilar helical antenna for use in wireless communications comprising:

an elongate core having a length, a distal end, a proximal end, an exterior major surface, and a helical groove in the exterior major surface extending between the proximal and the distal ends;

an electrically conductive radiating element having a first end, a second end, and a first electrical impedance, the radiating element resting in the helical groove in the exterior major surface of the elongate core, the first end terminating adjacent to the distal end of the elongate core and the second end terminating adjacent to the proximal end of the elongate core;

a back plate attached to the proximal end of the elongate core; and

an impedance matching section that has a narrow end, a wide end, and a shape, the shape comprising the area between an inner arcuate margin and an outer margin, the outer margin flaring from the narrow end of the impedance matching section to the wide end of the impedance matching section, such that the narrow end has a second electrical impedance for matching the first electrical impedance of the radiating element and is connected to the second end of the radiating element, and such that the wide end is adapted for connecting to an electrical connector end has a third electrical impedance for matching an electrical impedance of the electrical connector, in which the inner arcuate margin of the impedance matching section is seated in the helical groove adjacent to the point at which the impedance matching section is connected to the second end of the radiating element.

12. The antenna of claim 10 in which the first impedance and the second impedance are 110 ohms and the third impedance is 50 ohms and the impedance matching section is a predetermined distance from the back plate.