Antenna for rfid reader
AssigneeSymbol Technologies, Inc.
InventorMark DURON
Life of this patent
Estimating the term…
Abstract
An antenna for using within an allocated bandwidth having a nominal center frequency includes a support member, a first antenna structure, and a second antenna structure. The first antenna structure has a return loss maximized at a first optimal frequency. The second antenna structure has a return loss maximized at a second optimal. The difference between the first optimal frequency and the second optimal frequency is more than 10% of the allocated bandwidth but less than 100% of the allocated bandwidth.
Claims15
An antenna of an RFID reader for using within an allocated bandwidth of the RFID reader having a nominal center frequency comprising:
- a first antenna structure for emitting and receiving electromagnetic waves primarily in a first polarization, the first antenna structure having a return loss maximized at a first optimal frequency;
- a second antenna structure for emitting and receiving electromagnetic waves primarily in a second polarization that is orthogonal to the first polarization, the second antenna structure having a return loss maximized at a second optimal frequency;
- and
- wherein the difference between the first optimal frequency and the second optimal frequency is more than 10% of the allocated bandwidth but less than 100% of the allocated bandwidth of the RFID reader.
A method of generating RF electromagnetic waves with an antenna of an RFID reader at frequencies in the vicinity of a nominal center frequency, the antenna comprising (1) a first antenna structure for emitting and receiving electromagnetic waves primarily in a first polarization;
- (2) a second antenna structure for emitting and receiving electromagnetic waves primarily in a second polarization that is orthogonal to the first polarization, and (3) wherein the first antenna structure has a return loss maximized at a first optimal frequency that is higher than the nominal center frequency and the second antenna structure has a return loss maximized at a second optimal frequency is lower than the nominal center frequency, the method comprising:
- selecting a channel frequency from multiple channel frequencies within an allocated bandwidth;
- comparing the selected channel frequency with the nominal center frequency;
- and
- generating the electromagnetic waves with either the first antenna structure or the second antenna structure based upon the comparing, wherein the generating the electromagnetic waves comprises,
- generating the electromagnetic waves with the first antenna structure when the selected channel frequency is higher than the nominal center frequency, and
- generating the electromagnetic waves with the second antenna structure when the selected channel frequency is lower than the nominal center frequency.
A method of generating electromagnetic waves by an RFDI reader using channel frequencies within an allocated bandwidth having a nominal center frequency comprising:
- generating with a first antenna structure in the RFID reader electromagnetic waves primarily in a first polarization at channel frequencies higher than the nominal center frequency, the first antenna structure having a return loss maximized at a first optimal frequency that is higher than the nominal center frequency;
- and
- generating with a second antenna structure in the RFID reader electromagnetic waves primarily in a second polarization at channel frequencies lower than the nominal center frequency, the second polarization being orthogonal to the first polarization, and the second antenna structure having a return loss maximized at a second optimal frequency that is lower than the nominal center frequency.
Dependencies are inferred from the claim text.