Small omni-directional, slot antenna

• US 6,052,093 A
• Filed: 12/09/1997
• Issued: 04/18/2000
• Est. Priority Date: 12/18/1996
• Status: Expired due to Term

• Current Assignee: Savi Technology Incorporated
• Original Assignee: Savi Technology Incorporated
• Inventors: Yao, Nian Jing, Verma, Vikram, Peterson, Patrick
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): Ho, Tan
• Application Number:
  US08/987,435
• Time in Patent Office: 861 Days
• Field of Search: 343/767, 343/770, 343/860, 343/846, 343/702
• US Class Current: 343/770
• CPC Class Codes: H01Q 1/22 by structural association with other equipment or articles
• 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 13/16 Folded slot antennas
• CPC Class Codes: H05K 1/16 incorporating printed electric components, e.g. printed resistor, capacitor, inductor

Abstract

This invention discloses a small slot antenna incorporated within a flat circuit board and having a three dimension omni-directional radiation pattern. In one embodiment, the antenna is formed as an L shaped slot along two edges of the circuit board of a miniature radio transceiver. The antenna is ideally suited for use in applications where radio frequency inventory tags (operating in the high VHF to low UHF frequency ranges of 400 to 500 mHz) are associated with items for which a high level of inventory control is required. It is important that such tags be able to communicate with vertical and horizontal polarized signals with reasonable gain. This invention features a low cost for manufacture and has application in radio communications in general wherever there is a requirement for a small transceiver with an integrated, orientation insensitive antenna.

Claims

1. A combination omni-directional slot antenna and electronic circuitry comprising:

a circuit board having a first selected dimension and a second selected dimension substantially perpendicular to said first dimension;

electronic circuitry mounted to said circuit board, said electronic circuitry including at least one of receiving and transmitting circuitry and a first impedance matching network;

a first slot antenna arm formed in said circuit board parallel to said first dimension;

a second slot antenna arm formed in said circuit board parallel to said second dimension, one end of said first slot antenna arm joined to a selected location of said second slot antenna arm such that said first slot antenna arm is substantially perpendicular to said second slot antenna arm and forms said first omni-directional slot antenna, said first impedance matching network connected between said first omni-directional slot antenna and said at least one of said receiving and transmitting circuitry; and

an antenna ground plane formed on said circuit board and surrounding both said first and second slot antenna arms.

2. The combination antenna of claim 1 wherein said first slot antenna arm is formed along one edge of said circuit board and said second antenna arm is formed along an adjoining edge of said circuit board such that said first and second antenna arms form a substantially "L" shaped slot antenna.

3. The combination antenna of claim 2 and further including a portion of said circuit board located where said first slot antenna arm joins said second slot antenna arm to provide mechanical strength.

4. The combination antenna of claim 1 wherein said one end of said first slot antenna arm is joined to an end of said second slot antenna arm such that said first and second antenna arms substantially form an "L" shaped slot antenna.

5. The combination antenna of claim 1 wherein said first slot antenna arm is joined to said second slot antenna arm at a selected location between the two ends of said second antenna arm and that said first and second antenna arms substantially form a "T" shaped slot antenna.

6. The combination antenna of claim 1 and further including an electronic circuit ground plane provided with said circuit board and a single electrical connection between said antennas ground plane and said electronic circuit ground plane.

7. The combination antenna of claim 6 wherein said electronic circuit ground plane is formed as an integral layer within said circuit board.

8. The combination of claim 2, wherein said first impedance matching network is connected to said receiving circuitry, and further including a third slot antenna arm formed in said circuit board at an edge parallel to and opposite said first slot antenna arm;

a fourth slot antenna arm formed in said circuit board at an edge parallel to an opposite said second slot antenna arm, one end of said third slot antenna arm joined to an end of said fourth slot antenna arm such that said third and fourth antenna arm form a second substantial "L" shaped slot antenna;

a second antenna ground plane formed on said circuit board and surrounding said third and fourth slot antenna arms; and

wherein said electronic circuitry includes a second impedance matching network to match the impedance of said second "L" shaped slot antenna to said transmitting circuitry.