ANTENNA WITH EMBEDDED WIDEBAND MATCHING SUBSTRATE

• US 20150116182A1
• Filed: 10/31/2013
• Published: 04/30/2015
• Est. Priority Date: 10/31/2013
• Status: Active Grant

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola Solutions, Inc.
• Inventors: CONTRERAS, NEREYDO T., FARAONE, ANTONIO, WILLIAMS, WILLIAM R., BIT-BABIK, GIORGI
• Granted Patent: US 9,887,462 B2
• Time in Patent Office: Days
• US Class Current: 343/860
• CPC Class Codes: H01Q 1/242 specially adapted for hand-held use
• CPC Class Codes: H01Q 11/08 Helical antennas
• CPC Class Codes: H01Q 5/335 at the feed, e.g. for impedance matching
• CPC Class Codes: H01Q 5/50 Feeding or matching arrangements for broad-band or multi-band operation
• CPC Class Codes: H01Q 9/30 with feed to end of elongated active element, e.g. unipole H01Q9/44 takes precedence
• CPC Class Codes: H03H 7/38 Impedance-matching networks

Abstract

An antenna (100) with an embedded wideband matching substrate (102) is provided. The substrate (102) comprises impedance matching circuitry (300) providing a low frequency (LF) matching circuit (330) and a high frequency (HF) matching circuit (340) for tri-band operation. A stripline (314) having a stripline ground (324) is disposed on the substrate. The stripline (314) provides a matching element and the stripline ground (324) provides a common ground (324) for both the HF and LF matching circuits. The substrate (102) is shaped with a tabular portion (106) which facilitates encasing the substrate (102) within a casing (118). The tabular portion (106) further provides an alignment feature for wrapping of a flexible radiating element about the casing and flexible antenna rod (126) to complete the antenna structure (100).

Claims

1. An impedance matching structure for an antenna, comprising:

a printed circuit board (PCB);

a low frequency (LF) matching circuit disposed on the PCB;

a high frequency (HF) matching circuit disposed on the PCB; and

a stripline disposed on the PCB, the stripline providing a common ground for the HF and LF matching circuits, and the PCB having no dedicated ground layer.

2. The impedance matching structure of claim 1, wherein the stripline operates as a matching element and ground to provide a return current path for both high and low frequency.

3. The impedance matching structure of claim 1, further comprising:

an antenna feed point disposed on the PCB; and

wherein components of the HF matching circuit are placed proximate to the antenna feed point.

4. The impedance matching structure of claim 1, wherein the common ground provided by the stripline minimizes coupling between the LF matching circuit and the HF matching circuit.

5. The impedance matching structure of claim 1, wherein the PCB comprises a tabular portion.

6. The impedance matching structure of claim 5, further comprising:

a casing having slots; and

the tabular portion of the PCB being retained within slots of the casing.

7. The impedance matching structure of claim 6, wherein the tabular portion of the PCB prevents rotation of the PCB within the casing.

8. The impedance matching structure of claim 6, wherein the casing is formed of first and second casing halves.

9. The impedance matching structure of claim 1, wherein the LF matching circuit operates over a VHF band, and the HF matching circuit operates over a UHF band and a 7/800 MHz band.

10. An antenna, comprising:

a casing;

a flexible rod coupled to the casing;

a rolled conductive strip wrapped about the casing with overlapping successive turns;

a printed circuit board (PCB) retained within the casing;

impedance matching circuitry disposed on the PCB, the impedance matching circuitry comprising a low frequency (LF) matching circuit, a high frequency (HF) matching circuit, and a stripline; and

the stripline coupling the LF matching circuit and the HF matching circuit, the stripline having a stripline ground providing a common ground to the LF matching circuit and the HF matching circuit, the PCB having no dedicated ground layer.

11. The antenna of claim 10, further comprising:

first and second slots within the casing;

tabs on the PCB; and

the tabs of the PCB being retained within the slots of the casing.

12. The antenna of claim 10, wherein the stripline comprises a predetermined length and predetermined width, and wherein the predetermined length and predetermined width of the stripline and the LF matching circuit and the HF matching circuit control a broadband frequency of the antenna.

13. The antenna of claim 10, wherein the antenna has a length shorter than or equal to 20 centimeters (cm).

14. The antenna of claim 10, further comprising:

an internal alignment feature molded into the flexible rod; and

a dé

tente feature coupled to the casing, the alignment feature and dé

tente feature for capturing and retaining the flexible rod to the casing.

15. The antenna of claim 10, wherein the common ground provided by the stripline comprises a predetermined width of no more than 10 times that of the stripline.

16. The antenna of claim 10, wherein the LF matching circuit operates over a VHF band, and the HF matching circuit operates over a UHF band and a 7/800 MHz band.

17. The antenna of claim 10, wherein the LF matching circuit and the HF matching circuit are formed as a diplexer providing a first LF path and a second HF path joining at an antenna feed point.

18. The antenna of claim 10, further comprising a helical radiator element wrapped about the casing and flexible rod.