Multi-Patch RFID Antenna for Broadband UHF Signal Coverage
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Solution Overview
Problem
Conventional patch antennas for UHF RFID applications face challenges with narrow bandwidth, increased thickness, and complex field distribution, leading to signal detuning and dead zones, which hinder reliable communication with RFID tags in environments with varying surroundings.
Innovation Solution
A low-cost, low-thickness patch antenna design featuring two or more connected radiating elements and a reference ground conductor in the same geometric plane or closely spaced parallel planes, with optional direct electrical short connections for electrostatic discharge protection, enhancing bandwidth and radiation efficiency while simplifying feed cable attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional patch antenna design is used, then the antenna structure is simple, but the bandwidth is narrow and the resonance frequency is easily detuned by environmental factors
Solution Approach 1:
The antenna is divided into multiple radiating elements (first, second, and third elements) with different geometries and resonant frequencies. Each element contributes to a different portion of the UHF band, creating a composite wideband response. The elements are spatially segmented and fed with appropriate phase relationships to achieve constructive interference across the bandwidth.
Solution Approach 2:
The antenna employs a composite structure combining multiple radiating elements with different electrical characteristics. The first element has a higher resonant frequency than the second element, which in turn has a higher frequency than the third element. This composite arrangement creates a broadband antenna that overcomes the narrow bandwidth limitation of conventional single-element patch antennas.
2Length of stationary object
If the antenna thickness is reduced for low-profile applications, then the aesthetic appearance and space efficiency improve, but the radiation efficiency decreases and bandwidth narrows
Solution Approach 1:
The antenna elements are arranged in a three-dimensional configuration with specific spacing relationships. The first and second elements are separated by a first distance, while the second and third elements are separated by a second distance. This spatial arrangement in multiple dimensions allows the thin antenna to achieve wideband performance and good radiation efficiency without increasing the profile thickness.
Solution Approach 2:
The antenna employs phase-shifting mechanisms to dynamically control the radiation pattern and impedance matching across the operating bandwidth. By adjusting the phase relationships between the multiple radiating elements, the antenna maintains optimal radiation efficiency and bandwidth performance despite the reduced thickness.
3Area of stationary object
If conventional single-element patch antenna is used, then the fabrication is simple, but the field distribution creates dead zones and poor spatial coverage
Solution Approach 1:
The antenna is segmented into multiple radiating elements distributed in space, each contributing to different regions of the coverage area. This segmentation eliminates dead zones by ensuring uniform field distribution across the entire service area, with each element responsible for illuminating specific spatial zones.
Solution Approach 2:
The multiple radiating elements are combined with specific phase relationships to create a unified wide coverage pattern. The first, second, and third elements work together constructively to provide omnidirectional or sector-wide coverage, merging their individual radiation patterns into a comprehensive coverage area that eliminates dead zones.
4Adaptability or versatility
If the antenna is designed for wideband operation, then the adaptability to different frequencies improves, but the resonance frequency becomes sensitive to environmental detuning
Solution Approach 1:
The antenna uses a composite structure of multiple radiating elements with staggered resonant frequencies. The first element resonates at a higher frequency than the second, which resonates higher than the third. This composite frequency distribution creates a broadband response that is inherently more stable and less susceptible to environmental detuning, as the multiple resonant peaks provide redundancy.
Solution Approach 2:
The antenna design employs parameter optimization including specific spacing distances between elements, controlled phase shifts, and adjusted impedances. These parameter changes are optimized to maintain stable resonance characteristics across the UHF band while reducing sensitivity to environmental factors such as nearby objects and mounting variations.
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
The design achieves improved bandwidth, increased radiation gain, and reduced thickness, minimizing dead zones and enhancing the reliability of RFID communication across a wider area with better spatial resolution and aesthetics.
Implementation Method 1
two or more connected radiating elements... for transmitting and receiving radio frequency (RF) signals
Implementation Method 2
optionally including a direct electrical short connection (DC closed short circuit) between the patch system and the ground conductor for the dissipation of electrostatic charge
Data Source
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AI summary
Described herein is an antenna for use with a radio frequency identification system, the antenna including a reference ground; an antenna feed; a primary patch antenna element for mid-field transmission and reception of one of HP and UHF signals, wherein the primary patch antenna element is electrically coupled to the antenna feed; and one or more additional patch antenna elements for mid-field transmission and reception of the one of HF and UHF broadband signals, wherein each of the one or more additional patch antenna elements is electrically connected to an edge of the primary patch antenna element for transmission and reception of the one of HF and UHF signals. The one or more additional patch antenna elements provide for gain enhancement of the one of HF and UHF signals.