Inverted F antenna system and RFID device having same

• US 9,317,798 B2
• Filed: 06/25/2012
• Issued: 04/19/2016
• Est. Priority Date: 08/29/2007
• Status: Active Grant

• Current Assignee: Zest Labs, Inc.
• Original Assignee: Intelleflex Corporation
• Inventors: Sardariani, Edmond, Birnbaum, Thomas, Ramisetti, Sireesha, Ghosh, Debalina
• Primary Examiner(s): Levi, Dameon E
• Assistant Examiner(s): Hu, Jennifer F
• Application Number:
  US13/532,694
• Publication Number:
  US 20120268327A1
• Time in Patent Office: 1,394 Days
• Field of Search: 343/700.MS, 343/893
• US Class Current: 1/1
• CPC Class Codes: G06K 19/07749 the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
• CPC Class Codes: H01Q 1/2208 associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems methods or arrangements for sensing record carriers, e.g. for reading patterns G06K7/00; record carrier for use with machines and with at least a part designed to carry digital markings G06K19/00
• 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 23/00 Antennas with active circuits or circuit elements integrated within them or attached to them
• CPC Class Codes: H01Q 9/0421 with a shorting wall or a shorting pin at one end of the element H01Q9/0414 takes precedence
• CPC Class Codes: H01Q 9/145 by varying the electrical length

Abstract

An RFID device according to one embodiment includes an active portion of a first inverted F antenna; a feed electrically coupled to the active portion; an active portion of a second inverted F antenna, a feed electrically coupled to the second active portion; a ground plane spaced from the active portions; and an RFID controller coupled to the feeds. An RFID device according to another embodiment includes an inverted F antenna having an active portion, a ground plane spaced from the active portion, and a feed coupled to the active portion, wherein the active portion includes multiple aims, a first of the arms having a first length and a second of the arms having a second length; and an RFID controller coupled to the feed.

Claims

1. An RFID device, comprising:

a substrate;

a first active portion of a first inverted F antenna extending along a topside of the substrate;

a first feed electrically coupled to the first active portion;

a second active portion of a second inverted F antenna extending along an underside of the substrate such that the first active portion of the first inverted F antenna and the second active portion of the second inverted F antenna lie along parallel but spaced apart planes, wherein the second active portion of the second inverted F antenna is arranged in an opposite orientation relative to an orientation of the first active portion of the first inverted F antenna, such that the second active portion is rotated about 180 degrees from the orientation of the first active portion relative to a central axis perpendicular to a face of the substrate;

a second feed electrically coupled to the second active portion;

a ground plane spaced from the active portions;

an RFID controller coupled to the feeds; and

a battery coupled to the RFID controller, wherein the battery is positioned between the active portions of the inverted F antennas and the ground plane, such that the active portions of the inverted F antennas are on a first side of the battery and the ground plane is on a second side of the battery that is opposite of the first side.

2. The RFID device as recited in claim 1, wherein one terminal of the battery is in direct electrical communication with the ground plane.

3. The RFID device as recited in claim 1, wherein the first active portion of the first inverted F antenna is electrically isolated from the second active portion of the second inverted F antenna by a dielectric material.

4. The RFID device as recited in claim 1, wherein a length of the first active portion of the first inverted F antenna is different than a length of the second active portion of the second inverted F antenna such that each inverted F antenna is tuned to a different frequency.

5. The RFID device as recited in claim 1, further comprising an extension portion being selectively coupleable to the first active portion of the first inverted F antenna for altering a resonant frequency of the first inverted F antenna.

6. The RFID device as recited in claim 1, wherein the active portions are on a same side of the ground plane.

7. The RFID device as recited in claim 1, wherein one or more of the first inverted F antenna and the second inverted F antenna is designed to match an impedance of the RFID controller.