LOOP ANTENNA AND METHOD FOR SWITCHING THE SAME

• US 20150144694A1
• Filed: 04/11/2014
• Published: 05/28/2015
• Est. Priority Date: 11/26/2013
• Status: Abandoned Application

• Current Assignee: Electronics and Telecommunications Research Institute
• Original Assignee: Electronics and Telecommunications Research Institute
• Inventors: CHOI, Won Kyu, YANG, Hoe-Sung, PARK, Chan-Won, PYO, Cheol Sig, SON, Hae-Won
• Application Number:
  US14/251,238
• Publication Number:
  US 20150144694A1
• Time in Patent Office: Days
• US Class Current: 235/439
• CPC Class Codes: G06K 7/10148 the step consisting of dynamically tuning the resonant circuit of the interrogation device that is emitting the interrogation signal, e.g. for impedance matching inside of the interrogation device for tuning related to loop aerials in general H01Q7/00
• CPC Class Codes: G06K 7/10336 the antenna being of the near field type, inductive coil
• CPC Class Codes: G06K 7/10356 using a plurality of antennas, e.g. configurations including means to resolve interference between the plurality of antennas

Abstract

The loop antenna includes a loop coil connected to an RF signal source of a reader through a feed cable, and a switch that is turned on and off depending on a DC voltage that is proportional to the magnitude of an RF signal supplied from the RF signal source of the reader and opens the loop coil when turned off and closes the loop coil when turned on.

Claims

1. A loop antenna:

a loop coil connected to an RF signal source of a reader through a feed cable; and

a switch that is turned on and off depending on a DC voltage that is proportional to the magnitude of an RF signal supplied from the RF signal source of the reader, and opens the loop coil when turned off and closes the loop coil when turned on.

2. The loop antenna of claim 1, further comprising:

a signal extractor that extracts part of the RF signal; and

a rectifier that rectifies the extracted RF signal and converts the rectified RF signal into the DC voltage.

3. The loop antenna of claim 2, wherein the signal extractor comprises an inductor connected between a power line of the feed cable and the rectifier.

4. The loop antenna of claim 1, wherein the switch comprises a relay switch.

5. The loop antenna of claim 1, further comprising an impedance matching unit that matches the impedance between the feed cable and the loop antenna.

6. A method for switching a loop antenna, the method comprising:

generating a DC voltage that is proportional to the magnitude of an RF signal output from an RF signal source of a reader; and

closing or opening a loop coil constituting the loop antenna depending on the DC voltage.

7. The method of claim 6, wherein the loop antenna comprises a switch connected in the loop coil, and

the closing or opening comprises:

if the DC voltage is higher than a driving voltage of the switch, turning the switch on to close the loop coil; and

if the DC voltage is lower than the driving voltage of the switch, turning the switch off to open the loop coil.

8. The method of claim 7, wherein the switch comprises a relay switch.

9. The method of claim 6, wherein the generating comprises:

extracting part of the RF signal; and

rectifying the extracted RF signal and converting the rectified RF signal into the DC voltage.