Hybrid antenna for portable radio communication devices

• US 9,363,794 B1
• Filed: 12/15/2014
• Issued: 06/07/2016
• Est. Priority Date: 12/15/2014
• Status: Active Grant

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola Solutions, Inc.
• Inventors: Oon, Alexander Chin Keong, Goh, Teik Yang, Lim, Hiang Yaol Derrick, Bit-Babik, Giorgi
• Primary Examiner(s): Nguyen, Hai V
• Application Number:
  US14/570,271
• Publication Number:
  US 20160174197A1
• Time in Patent Office: 540 Days
• Field of Search: 455/77, 455/193.1
• US Class Current: 1/1
• 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 5/335 at the feed, e.g. for impedance matching
• CPC Class Codes: H01Q 9/145 by varying the electrical length
• CPC Class Codes: H04B 1/401 for selecting or indicating operating mode
• CPC Class Codes: H04M 1/72448 with means for adapting the functionality of the device according to specific conditions
• CPC Class Codes: H04W 88/06 adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals

Abstract

A hybrid antenna structure allows the antenna to be used internally or mostly internally in a portable radio communication device operating in the VHF range. The hybrid antenna structure includes a switching circuit that connects an RF circuit to one of several points along the length of a wrapped conductor element, depending on the selected operating frequency. An inductive matching tail element is adjustably tuned to match the selected tap point on the wrapped conductor for the selected operating frequency.

Claims

1. An internal antenna structure for a portable radio communication device, comprising:

a feed line connected to a radio frequency (RF) circuit;

a switching circuit having an input connected to the feed line and having a plurality of selectable outputs, the switching circuit is operable to connect the input to a selected one of the plurality of selectable outputs;

an inductive matching tail element connected between the feed line and a reference potential; and

a wrapped conductor element having a plurality of tap points along a length of the wrapped conductor element;

wherein each of the plurality of selectable outputs of the switching circuit is coupled exclusively to a respective one of the plurality of tap points.

2. The internal antenna structure of claim 1, wherein the inductive matching tail element is a conductor having a meander shape.

3. The internal antenna structure of claim 1, wherein the wrapped conductor element comprises a meander element.

4. The internal antenna structure of claim 1, wherein the wrapped conductor element comprises a helical element coupled to the meander element.

5. The internal antenna structure of claim 1, wherein the wrapped conductor element comprises a meander element coupled to a spiral element.

6. The internal antenna structure of claim 1, wherein the wrapped conductor element is formed in a flexible circuit board that is wrapped around an internal space of the portable radio communication device.

7. The internal antenna structure of claim 1, wherein the switching circuit connects the input to the selected one of the plurality of selectable outputs based on a selected operating frequency of the RF circuit.

8. The internal antenna structure of claim 7, wherein the selected operating frequency is a frequency band from 30 MHz to 300 MHz.

9. The internal antenna structure of claim 1, wherein the wrapped conductor element has a termination connected to an external antenna element.

10. The internal antenna structure of claim 1, wherein the inductive matching tail element is connected to the reference potential through a tuning circuit that changes a matching impedance of the inductive matching element based on an operating frequency of the RF circuit.

11. A method of operating a portable radio communication device, comprising:

receiving an indication of a selected operating frequency;

determining a switching configuration for a switching circuit having an input connected to a radio frequency (RF) circuit via a feed line and a plurality of outputs, each one of the plurality of outputs connected to a respective tap point along a length of a wrapped conductor, wherein each tap point corresponds to a frequency band;

configuring the switching circuit to connect the feed line to a tap point corresponding to the selected operating frequency range; and

adjusting an inductive matching tail element connected between the feed line and a reference potential based on the selected operating frequency.

12. The method of claim 11, wherein receiving the indication of the selected operating frequency comprises receiving a channel section via a user interface of the portable radio communication device.

13. The method of claim 11, wherein configuring the switching circuit comprises configuring the switching circuit to connect the feed line to a tap point on a meander element of the wrapped conductor element.

14. A portable radio communication device, comprising:

a housing;

a circuit board disposed in the housing;

a wrapped conductor element disposed around an inner periphery of the housing so as to at least partially encircle a portion of the circuit board;

a radio frequency (RF) circuit connected to a feed line;

a switching circuit that selectively connects the feed line to one of a plurality of tap points along a length of the wrapped conductor element, wherein each tap point corresponds to a different frequency band; and

an inductive matching tail element connected between the feed line and a reference potential, and wherein the inductive matching tail element is selectively tuned in correspondence with a selection of one of the plurality of tap points.

15. The portable radio communication device of claim 14, wherein the inductive matching tail element is a conductor having a meander shape.

16. The portable radio communication device of claim 14, wherein the wrapped conductor element comprises a meander element formed on a flexible circuit board member.

17. The portable radio communication device of claim 14, wherein the wrapped conductor element comprises a helical element coupled to the meander element, wherein the helical element and the meander element are formed on a substrate that fits around the inner periphery of the housing.

18. The portable radio communication device of claim 14, wherein the wrapped conductor element comprises a meander element coupled to a spiral element, wherein the spiral element and the meander element are formed on a flexible circuit board member.

19. The portable radio communication device of claim 14, wherein the switching circuit connects the input to the selected one of the plurality of selectable outputs based on a selected operating frequency of the RF circuit.

20. The portable radio communication device of claim 14, wherein the wrapped conductor element has a termination connected to an external antenna element.