Helical antenna structure capable of resonating at two different frequencies

• US 4,442,438 A
• Filed: 03/29/1982
• Issued: 04/10/1984
• Est. Priority Date: 03/29/1982
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Balzano, Quirino, Siwiak, Kazimierz, Garay, Oscar M.
• Primary Examiner(s): Lieberman, Eli
• Application Number:
  US06/363,186
• Time in Patent Office: 743 Days
• Field of Search: 343/792, 343/895
• US Class Current: 343/792
• CPC Class Codes: H01Q 5/371 Branching current paths
• CPC Class Codes: H01Q 5/40 Imbricated or interleaved structures; Combined or electromagnetically coupled arrangements, e.g. comprising two or more non-connected fed radiating elements
• CPC Class Codes: H01Q 9/27 Spiral antennas
• CPC Class Codes: H01Q 9/30 with feed to end of elongated active element, e.g. unipole H01Q9/44 takes precedence

Abstract

An antenna is provided which exhibits a relatively small size and is capable of resonating at two different frequencies. The antenna includes two helically wound elements which resonate at a first resonant frequency. A conductive member extends through and beyond one of the two helical elements to cause the antenna to resonate at a second resonant frequency.

Claims

1. An antenna exhibiting first and second different predetermined resonant frequencies comprising:

a first helically configured electrically conductive element;

a second helically configured electrically conductive element, said first and second elements being coupled to a common feed port so as to together resonate at said first predetermined resonant frequency when radio frequency energy is supplied to said feed port, and

a first electrically conductive member including first and second portions, said first portion being situated within said first element, said second portion being situated external to said first element and extending from said first portion, said first member being coupled to said feed port and said first element such that said first member and said first element together resonate at said second predetermined resonant frequency when radio frequency energy is supplied to said feed port.

2. An antenna exhibiting first and second different predetermined resonant frequencies comprising:

a first helically configured conductive element having first and second opposed ends;

a second helically configured conductive element having first and second opposed ends, said first and second elements being aligned so as to share a common axis between the respective ends thereof, the first end of said first element being situated adjacent the first end of said second element to form adjacent ends each of which is coupled to a common feed port such that when radio frequency energy is applied thereto, said first and second element cooperate to resonate at said first resonant frequency, and

a first conductive member including first and second portions each exhibiting a predetermined length, said first portion being situated within said first element along said axis thereof, said second portion extending from said first portion a predetermined distance beyond the second end of said first element, said first conductive member being coupled to the first end of said first element and to said feed port such that when radio frequency energy is applied to said feed port, said first conductive member and said first conductive element cooperate to resonate at said second resonant frequency.

3. The antenna of claim 2 including a coaxial feed line having a center conductor and a ground conductor situated within said second conductive element and running along said axis thereof between the first and second ends of said second conductive element, said center conductor being coupled to said first conductive member, said ground conductor being coupled to the first end of said second conductive element.

4. The antenna of claim 2 wherein said helically configured first and second conductive elements are comprised of metallic ribbon.

5. The antenna of claim 2 including first separation means disposed between the first portion of said first member and said first conductive element, for holding said first portion spatially separated from said first conductive element.

6. The antenna of claim 3 including second separation means, disposed between said coaxial feed line and said second conductive element, for holding said coaxial feed line spatially separated from said second conductive element.

7. The antenna of claim 5 wherein said first separation means is comprised of electrically insulative material.

8. The antenna of claim 6 wherein said second separation means is comprised of electrically insulative material.