Antenna Structure with Asymmetric Patch and Tapered Feed for RFID
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Solution Overview
Problem
Conventional coupled microstrip slot patch antennas face challenges in impedance matching and have limited bandwidth, particularly failing to achieve high return loss in RFID frequency bands like 0.902GHz-0.928GHz.
Innovation Solution
The antenna structure features a rectangular antenna pattern with a second portion extending outwardly from a corner, a ground layer with slots, and two microstrip lines with varying widths and orientations, allowing for improved impedance matching and broadband performance by adjusting the frequency band resonance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional coupled microstrip slot patch antenna design is used, then the structure is simple and easy to manufacture, but the bandwidth is limited and return loss cannot achieve high performance (20 dB) in RFID frequency bands
Solution Approach 1:
The antenna pattern is divided into two distinct portions: a first rectangular portion and a second portion extending from a corner. This segmentation allows independent optimization of each portion's contribution to the overall bandwidth and impedance matching characteristics, enabling broadband performance while maintaining structural simplicity
Solution Approach 2:
The antenna pattern introduces asymmetry by extending the second portion from one corner of the rectangular first portion. This asymmetric configuration creates additional resonant modes and improves impedance matching across the RFID frequency band, achieving return loss ≥20 dB while expanding bandwidth beyond conventional symmetric designs
2Adaptability or versatility
If the size of the upper patch antenna is adjusted to change bandwidth, then bandwidth may be modified, but impedance matching becomes difficult to adjust and return loss performance deteriorates
Solution Approach 1:
The microstrip feed line is designed with non-uniform width, featuring a first section and a second section with different width dimensions. This local variation in geometric parameters allows precise control of impedance transformation and matching characteristics without requiring complex global redesign, making impedance matching easily adjustable while maintaining broadband performance
Solution Approach 2:
The invention utilizes parameter optimization by varying the width dimensions of different microstrip line sections and the geometric parameters of the antenna pattern portions. By systematically adjusting these parameters, the design achieves both broadband operation and optimal impedance matching (return loss ≥20 dB) without complicating the manufacturing process
3Ease of manufacture
If conventional single-layer microstrip feed is used, then manufacturing is simple, but bandwidth is limited and cannot meet RFID frequency band requirements
Solution Approach 1:
The feed structure transitions from a conventional planar single-layer microstrip to a three-dimensional multi-layer configuration with ground layers separated by dielectric substrates. This dimensional expansion creates additional electromagnetic coupling paths and resonant modes, significantly broadening the bandwidth while maintaining manufacturing simplicity through standard PCB fabrication techniques
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 design achieves a broadband and high return loss, suitable for RFID applications, with return loss greater than or equal to 20 dB across the 0.902GHz to 0.928GHz frequency band.
Implementation Method 1
the antenna structure is suitable for resonating at a frequency band
Implementation Method 2
the microstrip line located below feeds input signals through the slot to feed the electric field to the patch antenna
Data Source
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AI summary
An antenna structure includes an antenna pattern, a ground layer and two microstrip lines. The antenna pattern includes a first portion and a second portion. The first portion is rectangle shape and includes a first, a second, a third and a fourth sides. The second portion protrudes outwardly from the first side and the second side. The ground layer has two slots. Projections of the two slots to the antenna pattern are close to the third and the fourth sides. Projections of the two microstrip lines to the antenna pattern are perpendicular to the third and the fourth sides. Each microstrip line has a first section and a second section. Projection of the second section to the antenna pattern is closer to a center of the first portion than projection of the first section. A width of the first section is greater than a width of the second section.