Miniaturized 2x2 Array Antenna Side Lobe Reduction
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Solution Overview
Problem
Miniaturization of array antennas while reducing side lobes and grating lobes is necessary to enhance the accuracy of movement direction detection in RFID tag communication systems, as existing methods with fewer antenna elements suffer from increased side lobe sizes, degrading detection accuracy.
Innovation Solution
An array antenna configuration with four elements arranged in a square shape, using variable phase shifters to control the feeding phases of each antenna element, ensuring the directivity direction of the beam can be adjusted along specific virtual lines, thereby minimizing side and grating lobes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the number of antenna elements is reduced to 2x2=4 elements for miniaturization, then the array antenna size is reduced, but side lobes and grating lobes become too large which degrades movement direction detection accuracy
Solution Approach 1:
The patent applies different power distribution ratios to different antenna elements within the 2x2 array. Specifically, the central antenna elements are assigned higher power distribution ratios while edge elements receive lower ratios. This local differentiation of quality (power distribution) allows the miniaturized 4-element array to suppress side lobes and grating lobes effectively, maintaining movement direction detection accuracy despite the reduced number of elements.
2Measurement precision
If power distribution ratio control is used to reduce side lobes, then side lobe levels are reduced, but the control system becomes more complex
Solution Approach 1:
The patent changes the power distribution ratio parameter for each antenna element based on its position in the 2x2 array. By optimizing these power distribution parameters (assigning higher ratios to central elements and lower ratios to edge elements), the system achieves effective side lobe suppression. This parameter optimization approach provides a straightforward control method that reduces side lobes without requiring complex control systems.
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 allows for the miniaturization of the array antenna while maintaining accurate detection of movement directions by significantly reducing side lobes, thus enhancing the overall performance of the RFID tag communication system.
Implementation Method 1
controlling a phase of a signal flowing to each antenna element
Implementation Method 2
a beam of a radio wave emitted from the array antenna
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3~4(b)
AI summary
Provided are an array antenna capable of miniaturizing an array antenna while reducing side lobes, a tag communication device and tag communication system provided with the array antenna, and a beam control method for the array antenna. When XY coordinates and a feeding phase of each antenna element (21a to 21d) are defined as the antenna element (21a) (0, Y1) • ϕ1, the antenna element (21b) (-X1, 0) • ϕ2, the antenna element (21c) (X2, 0) • ϕ3, the antenna element (21d) (0, -Y2) • ϕ4, wavelengths of λ, and directivity directions of θ, each of the feeding phases is set so that the following conditional equations ϕ1 = ϕ4, ϕ2 = 2π • X1 • sin (θ) / λ +ϕ1, ϕ3 = ϕ1 -2π • X2 • sin (θ) / λ are all satisfied.