EAS RFID Antenna with Hatched Ground Plane
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Solution Overview
Problem
Existing EAS and RFID antenna combinations face challenges in reducing overall size while minimizing attenuation effects from eddy currents, particularly when integrating UHF RFID patch antennas with EAS loop antennas, which often require significant space and increased footprint.
Innovation Solution
The design combines an EAS loop antenna with an RFID patch antenna, where the RFID antenna features a hatched ground plane and patch, allowing for close proximity without significant attenuation, with the RFID patch either situated within or non-coplanar to the EAS loop antenna, reducing overall size and footprint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the RFID patch antenna is placed inside the EAS loop antenna to reduce overall size, then the antenna footprint is reduced, but eddy currents in the RFID ground plane significantly attenuate the EAS transmit field
Solution Approach 1:
The RFID ground plane is segmented into a hatched pattern rather than being a continuous solid plane. This segmentation breaks up the eddy current paths, reducing the attenuation effect on the EAS transmit field while maintaining the RFID antenna's functionality within the compact form factor
Solution Approach 2:
The RFID patch antenna is nested inside the EAS loop antenna structure. This nesting arrangement allows both antenna types to coexist in a compact configuration, with the RFID antenna positioned within the interior portion of the EAS loop to minimize overall footprint
2Reliability
If the EAS and RFID elements are placed far apart to minimize interaction, then interference between elements is reduced, but the overall size and footprint of the combination antenna increases significantly
Solution Approach 1:
The RFID patch antenna is nested within the interior portion of the EAS loop antenna, allowing both elements to be in close proximity without requiring the large separation distances that would increase footprint. This nested configuration enables compact integration while managing element interactions
Solution Approach 2:
The hatched ground plane pattern segments the RFID antenna structure to reduce eddy current effects, enabling closer placement of the RFID element within the EAS loop without excessive interference, thus maintaining compact dimensions
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enables a compact antenna system that maintains effective EAS and RFID transmission capabilities, suitable for handheld readers and other space-constrained applications, while minimizing eddy current-induced attenuation.
Implementation Method 1
The transmitter produces a predetermined excitation signal in a tag detection zone
Implementation Method 2
The RFID reader may transmit a radio-frequency ('RF') carrier signal to the RFID device
Implementation Method 3
The RFID device may respond to the carrier signal with a data signal encoded with information stored by the RFID device
Implementation Method 4
problems arise when this is done since the EAS transmit field is significantly attenuated due to the creation of eddy currents in the RFID ground plane which oppose the EAS field
Data Source
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AI summary
A combination EAS/RFID antenna for use in an EAS/RFID surveillance system. The antenna includes an EAS antenna element and an RFID antenna element. The EAS antenna element includes an EAS loop antenna defining an interior portion. The RFID antenna element includes an RFID patch antenna having a hatched conductor pattern. The RFID antenna element is situated proximate the EAS loop antenna in such a fashion that the overall size of the antenna is reduced.