Antenna for radio frequency identification systems
An antenna for a radio frequency identification (RFID) system and a method for communicating in an RFID system are provided. The antenna includes a first port configured to provide RFID communication in a first polarization plane and a second port configured to provide RFID communication in a second polarization plane. The first polarization plane is orthogonal to the second polarization plane.
1 . An antenna for a radio frequency identification (RFID) system, the antenna comprising:
a first port configured to provide RFID communication in a first polarization plane; and
a second port configured to provide RFID communication in a second polarization plane, the first polarization plane orthogonal to the second polarization plane.
2 . An antenna in accordance with claim 1 wherein the first polarization plane comprises horizontal polarization and the second polarization plane comprises vertical polarization.
3 . An antenna in accordance with claim 1 wherein the first and second ports are configured to connect to at least one of an RFID transmitter and an RFID receiver of an RFID reader.
4 . An antenna in accordance with claim 1 wherein the RFID communication comprises communication with at least one of a passive RFID tag and an active RFID tag.
5 . An antenna in accordance with claim 1 wherein the first polarization plane and the second polarization plane define a linear cross-polarization.
6 . An antenna in accordance with claim 1 wherein the first port and the second port are formed as part of one of a patch type antenna structure and a dipole antenna structure.
7 . An antenna in accordance with claim 1 further comprising a two-dimensional resonator with a first side of the two-dimensional resonator connected to the first port and a second side of the two-dimensional resonator connected to the second port.
8 . An antenna in accordance with claim 1 wherein the first and second ports are configured to be switched to each provide a transmit operation and a receive operation.
9 . An antenna in accordance with claim 1 further comprising a first set of radiating antenna elements.
10 . An antenna in accordance with claim 9 wherein the first set of radiating antenna elements comprises orthogonal antenna elements.
11 . An antenna in accordance with claim 9 further comprising a second set of radiating antenna elements offset from the first set of radiating antenna elements.
12 . An antenna in accordance with claim 11 wherein the second set of radiating antenna elements comprises orthogonal antenna elements.
13 . An antenna in accordance with claim 11 wherein the first set of radiating antenna elements are offset from the second set of radiating antenna elements by an angle of about forty-five degrees.
14 . An antenna in accordance with claim 11 further comprising a third port and a fourth port and wherein a first antenna element of the second set of radiating antenna elements is connected to the third port and a second antenna element of the second set of radiating antenna elements is connected to the fourth port.
15 . A radio frequency identification (RFID) reader comprising:
a transmitting portion configured to transmit RFID signals;
a receiving portion configured to received RFID signals from at least one RFID tag; and
a dual port polarized antenna configured having orthogonal polarization and configured to be connected to the transmitting portion and the receiving portion.
16 . An RFID reader in accordance with claim 15 wherein the dual port polarized antenna comprises a patch type antenna having a first set of orthogonal radiating antenna elements.
17 . An RFID reader in accordance with claim 16 wherein the dual port polarized antenna comprises a second set of orthogonal radiating antenna elements offset by an angle from the first set of orthogonal radiating antenna elements.
18 . An RFID reader in accordance with claim 15 further comprising a switch configured to switch connection of at least one of the transmitting portion and the receiving portion between a first port and a second port of the dual port polarized antenna.
19 . An RFID reader in accordance with claim 15 further comprising a handheld housing having the transmitting portion, receiving portion and dual port polarized antenna therein.
20 . A method for communicating in a radio frequency identification (RFID) system, the method comprising:
transmitting an RFID signal in a first polarization plane; and
receiving an RFID signal from an RFID tag in a second polarization plane, the first polarization plane orthogonal to the second polarization plane.