Printed circuit board antenna structure

• US 6,850,197 B2
• Filed: 01/31/2003
• Issued: 02/01/2005
• Est. Priority Date: 01/31/2003
• Status: Active Grant

• Current Assignee: Sensus Spectrum, LLC (Xylem, Inc.)
• Original Assignee: M&FC Holding, LLC
• Inventors: Paun, Cristian
• Primary Examiner(s): LE, HOANGANH T
• Application Number:
  US10/355,312
• Publication Number:
  US 20040150562A1
• Time in Patent Office: 732 Days
• Field of Search: H01/Q.124, H01/Q.138, 343/702, 343/700.MS, 343/846, 343/848, 343/873
• US Class Current: 343/702
• CPC Class Codes: H01Q 1/24 with receiving set
• CPC Class Codes: H01Q 1/243 with built-in antennas
• 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 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 9/42 with folded element, the folded parts being spaced apart a small fraction of the operating wavelength
• CPC Class Codes: H05K 1/16 incorporating printed electric components, e.g. printed resistor, capacitor, inductor

Abstract

A printed circuit board antenna structure for the transmission of radio frequency energy. The printed circuit board antenna of the present invention includes a circuit board subassembly having a component mounting section and an antenna section. The second planar surface of the circuit board includes a layer of conductive material along the component mounting section to define a ground plane. A radiating and impedance matching trace is applied to the second planar surface of the circuit board along the antenna section. The radiating and impedance matching trace includes a radiating strip extending parallel to the center axis of the circuit board and an impedance matching strip having a plurality of individual legs extending perpendicular to the center axis. The impedance matching strip has defined dimensions to match the impedance of the antenna driving circuit.

Claims

1. A printed antenna assembly for the transmission of electromagnetic waves, the printed antenna comprising:

a substantially planar circuit board having a first planar surface and a second planar surface, the first and second planar surfaces being parallel and spaced by a material thickness, the circuit board including a mounting section and an antenna section integrally formed with each other;

an antenna driving circuit mounted to the first surface of the mounting section for generating electromagnetic waves to be transmitted by the printed antenna;

a coating of electrically conductive material covering substantially all of the second planar surface of the mounting section of the circuit board, wherein the conductive material forms a ground plane for the circuit board and provides a radiating element for transmitting the electromagnetic wave;

a radiating strip formed on the antenna section of the circuit board and coupled to the radiating element for aiding in the transmission of electromagnetic waves; and

an impedance matching strip formed on the antenna section of the circuit board and coupled to the radiating strip, the impedance matching strip having an overall length selected to substantially match the impedance of the antenna driving circuit.

2. The printed antenna assembly of claim 1 wherein the impedance matching strip and the radiation strip are formed on the second side of the printed circuit board.

3. The printed antenna assembly of claim 2 wherein the impedance matching strip and the radiating strip are integrally formed with each other and are formed from electrically conductive material applied to the second surface of the antenna section.

4. The printed antenna assembly of claim 1 wherein the mounting section of the circuit board extends along a center axis and has a length parallel to the center axis that is greater than a width perpendicular to the center axis.

5. The printed antenna assembly of claim 4 wherein the radiation strip extends parallel to the center axis of the mounting section.

6. The printed antenna assembly of claim 5 wherein the impedance matching strip includes at least a first leg formed on the antenna section and extending perpendicularly to the radiation strip.

7. The printed antenna assembly of claim 4 wherein the mounting section includes a first edge surface and a second edge surface that define the width of the mounting section, the antenna section including a first edge surface generally parallel to and extending from the first edge surface of the mounting section, wherein the radiating strip is adjacent to the first edge of the antenna section.

8. A printed antenna assembly for the transmission of electromagnetic waves, the printed antenna comprising:

a substantially planar circuit board having a first planar surface and a second planar surface, the first and second planar surfaces being parallel and spaced by a material thickness, the circuit board including a mounting section extending along a center axis and an antenna section integrally formed with mounting section;

an antenna driving circuit mounted to the first surface of the mounting section for generating electromagnetic waves to be transmitted by the printed antenna;

a coating of electrically conductive material covering substantially all of the second planar surface of the mounting section of the circuit board, wherein the conductive material forms a ground plane for the circuit board and provides a radiating element for transmitting the electromagnetic wave;

a radiating strip formed on the antenna section of the circuit board and coupled to the radiating element for aiding in the transmission of electromagnetic waves, the radiating strip extending parallel to the center axis of the mounting section; and

an impedance matching strip formed on the antenna section of the circuit board and coupled to the radiating strip, the impedance matching strip having an overall length selected to substantially match the impedance of the antenna driving circuit,

wherein the impedance matching strip includes a first leg formed on the antenna section extending perpendicularly to the radiation strip and a second leg coupled to the first leg and extending parallel to the first leg.

9. The printed antenna assembly of claim 8 wherein the second leg is shorter than the first leg.

10. A printed antenna assembly for the transmission of electromagnetic waves, the printed antenna comprising:

a substantially planar circuit board having a first planar surface and a second planar surface, the first and second planar surfaces being parallel and spaced by a material thickness, the circuit board including a mounting section extending along a center axis and an antenna section integrally formed with the mounting section;

an antenna driving circuit mounted to the first surface of the mounting section for generating electromagnetic waves to be transmitted by the printed antenna;

a coating of electrically conductive material covering substantially all of the second planar surface of the mounting section of the circuit board, wherein the conductive material forms a ground plane for the circuit board and provides a radiating element for transmitting the electromagnetic wave;

a radiating strip formed on the antenna section of the circuit board and coupled to the radiating element for aiding in the transmission of electromagnetic waves, the radiation strip extending parallel to the center axis of the mounting section; and

an impedance matching strip formed on the antenna section of the circuit board and coupled to the radiating strip, the impedance matching strip having an overall length selected to substantially match the impedance of the antenna driving circuit,

wherein the impedance matching strip includes a plurality of legs each extending perpendicular to the radiating strip, wherein the plurality of legs are coupled to each other and spaced from each other to define a serpentine pattern.

11. A printed antenna for the transmission of electromagnetic waves, the printed antenna comprising:

a substantially planar circuit board formed from a dielectric material and having a first planar surface and a second planar surface, the first and second planar surfaces being parallel and spaced by a material thickness, the circuit board having a first edge surface and a second edge surface equally spaced from a center axis;

a mounting section contained on the circuit board;

an antenna section contained on the circuit board and integrally formed with the mounting section;

a coating of electrically conductive material applied to the second planar surface and covering substantially all of the mounting section of the circuit board, wherein the conductive material forms a ground plane for the circuit board and functions as a radiating element for transmitting electromagnetic waves; and

a radiating and impedance matching trace formed on the second planar surface of the antenna section of the circuit board, the radiating and impedance matching trace including a radiating strip extending parallel to the center axis of the circuit board and an impedance matching strip coupled to the radiating strip and having at least a first leg positioned perpendicular to the radiating strip.

12. The printed antenna assembly of claim 11 wherein the radiating strip is positioned adjacent to the first edge of the circuit board along the antenna section.

13. The printed antenna assembly of claim 11 further comprising an antenna driving circuit mounted to the first surface of the mounting section for generating electromagnetic waves to be transmitted by the printed antenna.

14. A printed antenna for the transmission of electromagnetic waves, the printed antenna comprising:

a substantially planar circuit board formed from a dielectric material and having a first planar surface and a second planar surface, the first and second planar surfaces being parallel and spaced by a material thickness, the circuit board having a first edge surface and a second edge surface equally spaced from a center axis;

a mounting section contained on the circuit board;

an antenna section contained on the circuit board and integrally formed with the mounting section;

a coating of electrically conductive material applied to the second planar surface and covering substantially all of the mounting section of the circuit board, wherein the conductive material forms a ground plane for the circuit board and functions as a radiating element for transmitting electromagnetic waves; and

a radiating and impedance matching trace formed on the second planar surface of the antenna section of the circuit board, the radiating and impedance matching trace including a radiating strip positioned adjacent to the first edge of the circuit board and extending parallel to the center axis of the circuit board and an impedance matching strip coupled to the radiating strip and having at least a first leg positioned perpendicular to the radiating strip,

wherein the first leg of the impedance matching strip is formed along the top edge of the circuit board and extends perpendicular to the radiating strip.

15. The printed antenna assembly of claim 14 wherein the impedance matching strip includes at least a second leg coupled to the first leg and extending parallel to the first leg.

16. The printed antenna assembly of claim 15 wherein the second leg is shorter than the first leg.

17. A printed antenna for the transmission of electromagnetic waves, the printed antenna comprising:

a substantially planar circuit board formed from a dielectric material and having a first planar surface and a second planar surface, the first and second planar surfaces being parallel and spaced by a material thickness, the circuit board having a first edge surface and a second edge surface equally spaced from a center axis;

a mounting section contained on the circuit board;

an antenna section contained on the circuit board and integrally formed with the mounting section;

a coating of electrically conductive material applied to the second planar surface and covering substantially all of the mounting section of the circuit board, wherein the conductive material forms a ground plane for the circuit board and functions as a radiating element for transmitting electromagnetic waves; and

a radiating and impedance matching trace formed on the second planar surface of the antenna section of the circuit board, the radiating and impedance matching trace including a radiating strip extending parallel to the center axis of the circuit board and an impedance matching strip coupled to the radiating strip,

wherein the impedance matching strip includes a plurality of legs each extending perpendicular to the radiating strip, wherein the plurality of legs are coupled to each other and spaced from each other to define a serpentine pattern.

18. A printed antenna assembly for the transmission of electromagnetic waves, the printed antenna comprising:

a substantially planar circuit board extending along a center axis and having a first planar surface and a second planar surface;

a coating of electrically conductive material covering a portion of the second planar surface of the circuit board, the coating of electrically conductive material forming a ground plane for the circuit board and providing a radiating element for the transmission of electromagnetic waves;

a radiating strip formed on the second planar surface of the circuit board, the radiating strip extending parallel to the center axis of the circuit board; and

an impedance matching strip formed on the second planar surface of the circuit board and coupled to the radiating strip, the impedance matching strip including at least a first leg extending perpendicular to the radiating strip and being electrically coupled thereto.

19. The printed antenna assembly of claim 18 further comprising an antenna driving circuit mounted to the first surface of the circuit board, the antenna driving circuit being mounted to the circuit board opposite the coating of electrically conductive material that forms the ground plane.