Low visibility radio antenna with dual polarization

• US 5,977,931 A
• Filed: 07/15/1997
• Issued: 11/02/1999
• Est. Priority Date: 07/15/1997
• Status: Expired due to Term

• Current Assignee: Laird Technologies Incorporated (DuPont de Nemours, Inc.)
• Original Assignee: Antenex, Inc. (Laird Limited)
• Inventors: Openlander, Wayne R.
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): Ho, Tan
• Application Number:
  US08/892,732
• Time in Patent Office: 840 Days
• Field of Search: 343/895, 343/872, 29/600
• 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
• CPC Class Codes: Y10T 29/49016 Antenna or wave energy "plumbing" making

Abstract

A low visibility, field-diverse antenna provides cross-polarized fields enhancing signal communications. A generally flat, but helical, antenna is achieved in conjunction with a core substrate about which the antenna is wrapped, wound, or fixed. The core substrate, pitch or angle of the helix, and length of the transmitting antenna are chosen for a specific resonant frequency. The length and width of the helix are chosen in order to dimension the helical antenna between its linear and circular polarization modes to thereby deliver field-diverse and cross-polarized transmission modes. In order to optimize the manufacturing process, holes may be created within the substrate. These holes are plated with conducting material so that conducting foil on opposite faces of the substrate may be electrically connected. The holes may be offset according to the pitch of the helix. Once the transmitting antenna has been fabricated upon the core substrate, the margin between the plated-through holes and the edge of the substrate may be separated by cutting, sawing, or stamping.

Claims

1. A low-visibility, field-diverse monopole antenna for providing communications comprising:

an antenna-supporting core comprising printed circuit board (PCB) substrate and having a width and a length, said antenna-supporting core being generally thin and approximating a square, said PCB substrate conducting from one flat side to another via at least a portion of a plated-through hole; and

an antenna, said antenna wrapped upon said core in a manner for a selected resonant frequency, said antenna radiating in a diverse manner with horizontal and vertical field components of a field radiated by said antenna substantially in phase and not circularly polarized;

whereby

the low-visibility, field-diverse antenna is realized having helical antenna characteristics without severe circular polarization radiation thereby promoting reliable communications.

2. The low-visibility, field-diverse monopole antenna of claim 1, wherein said antenna comprises conducting foil.

3. A low-visibility, field-diverse monopole antenna for providing communications, comprising:

a generally thin and approximately square antenna-supporting core comprising printed circuit board (PCB) substrate having a width and a length, said core conducting from one flat side to another via at least a portion of a plated-through hole in said core;

an antenna, said antenna comprising conducting foil fixed upon said core in a manner for a selected resonant frequency, said antenna radiating in a diverse manner with horizontal and vertical field components of a field radiated by said antenna are substantially in phase and not circularly polarized; and

a radome, said radome covering said core and said antenna, said radome comprising acetyl plastic, said radome having a dielectric constant of approximately 4 and changing the operating frequency of the antenna;

whereby

the low-visibility, field-diverse antenna is realized having helical antenna characteristics without severe circular polarization radiation thereby promoting reliable communications.

4. A method for constructing a low-visibility, field-diverse monopole antenna, the steps comprising:

providing an antenna-supporting core having plated-through holes whereby conduction can be made from one side of said antenna-supporting core to another;

providing a conductor;

fixing said conductor upon said core;

attaching said conductor to said core in a manner whereby a length of said conductor is engaged by said core in a manner for a selected resonant frequency, said conductor radiating in a diverse manner with horizontal and vertical field components of a field radiated by said conductor substantially in phase and not circularly polarized;

whereby

the low-visibility, field-diverse antenna is realized having helical antenna characteristics without severe circular polarization radiation thereby promoting reliable communications.

5. The method for constructing a low-visibility, field diverse monopole antenna of claim 4, wherein the step of attaching said conductor to said core further comprises:

attaching conducting foil on one side of said core connecting one plated-through hole with another.

6. The method for constructing a low-visibility, field diverse monopole antenna of claim 5, wherein the step of providing an antenna-supporting core further comprises:

said plated-through holes are present on opposite sides of said core, said plated-through holes on one side of said core are offset with respect to said plated-through holes on the other side of said core to establish a pitch of said conducting foil attaching a plated-through hole on one side of said core with a plated-through hole on the other side of said core.

7. The method for constructing a low-visibility, field diverse monopole antenna of claim 6, wherein said offset of said plated-through holes is selected to maintain resonance in conjunction with a length of said conductor.

8. The method for constructing a low-visibility, field diverse monopole antenna of claim 7, wherein the step of providing an antenna-supporting core further comprises:

providing an antenna-supporting core having plated-through holes inside a perimeter margin.

9. The method for constructing a low-visibility, field diverse monopole antenna of claim 8, the steps further comprising:

removing excess core material by removing said perimeter margin to create a minimally-sized antenna.

10. The method for constructing a low-visibility, field diverse monopole antenna of claim 9, wherein said plated-through holes are approximately fifty-thousandths inch (0.050") in diameter.

11. A method for constructing a low-visibility, field-diverse monopole antenna, the steps comprising:

providing an antenna-supporting core having offset plated-through holes of approximately fifty-thousandths inch (0.050") in diameter whereby conduction can be made from one side of said antenna-supporting core to another, said plated-through holes present in said core inside a perimeter margin thereof;

providing a conductor of conducting foil;

fixing said conductor upon said core by attaching conducting foil on one side of said core connecting one plated-through hole with another;

attaching said conductor to said core in a manner whereby a length of said conductor is engaged by said core in a manner for a selected resonant frequency as established by said offset of said plated-through holes, said conductor radiating in a diverse manner with horizontal and vertical field components of a field radiated by said conductor are substantially in phase and not circularly polarized; and

removing excess core material by removing said perimeter margin to create a minimally-sized antenna;

whereby

the low-visibility, field-diverse antenna is realized having helical antenna characteristics without severe circular polarization radiation thereby promoting reliable communications.