Nested Antenna Elements for Multi-Band Operation and Low SAR
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Solution Overview
Problem
Existing antenna units for portable wireless communication devices face challenges in being compact while operating on multiple frequency bands and maintaining low Specific Absorption Rate (SAR) to minimize radiation absorption by the human body.
Innovation Solution
The antenna unit design includes a combination of first and second antenna elements, with the second antenna element disposed between the first antenna element and the ground conductor, utilizing a trap circuit and parasitic or ground elements to resonate at different frequencies, thereby distributing electric currents and reducing SAR, while allowing for compact size and wideband operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the antenna unit is made compact to fit portable devices, then the device size is reduced, but the ability to operate on multiple frequency bands and maintain low SAR is compromised
Solution Approach 1:
The patent implements a nested antenna structure where the second antenna element is disposed between the first antenna element and the ground conductor. This nesting arrangement allows multiple antenna elements to occupy overlapping spatial regions, enabling multi-band operation within a compact footprint. The first antenna element operates at a first frequency band while the second antenna element operates at a second frequency band, and both elements are integrated within the same structural envelope, effectively nesting one antenna system within another.
Solution Approach 2:
The patent utilizes three-dimensional spatial arrangement by positioning the second antenna element between the first antenna element and the ground conductor in the vertical dimension. This dimensional arrangement allows the antenna unit to achieve multi-band operation without increasing the planar footprint, effectively using the vertical space to accommodate additional antenna elements and their associated trap circuits for different frequency bands.
2Adaptability or versatility
If multiple antenna elements are added to achieve wideband operation, then frequency coverage is improved, but the device complexity and size increase
Solution Approach 1:
The patent combines multiple antenna elements and their associated trap circuits into a single integrated antenna unit. The first antenna element with its trap circuit for the first frequency band, and the second antenna element with its trap circuit for the second frequency band, are merged into one compact structure. This merging approach allows wideband operation to be achieved without proportionally increasing overall device complexity, as the elements share common structural support and grounding arrangements.
3Volume of moving object
If antenna elements are positioned closer to the human body for compact design, then device size is reduced, but the Specific Absorption Rate (SAR) increases
Solution Approach 1:
The patent introduces trap circuits as intermediary components between the antenna elements and the ground conductor. These trap circuits are designed to resonate at specific frequencies and provide impedance transformation, which helps to isolate the antenna elements from the ground conductor and reduce direct coupling to the human body. The trap circuits act as mediators that allow the antenna to maintain compact size while managing electromagnetic energy distribution to control SAR levels.
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 effectively reduces the Specific Absorption Rate (SAR) and allows the antenna unit to operate on multiple frequency bands with improved radiation efficiency and compact size, meeting the demands of wireless performance and regulatory requirements.
Implementation Method 1
a first antenna element and a second antenna element, with the second antenna element disposed between the first antenna element and the ground conductor, respectively, resonating at a first frequency and a second frequency
Implementation Method 2
a trap circuit connected between a second end of the first antenna element and a connection point on the ground conductor, the trap circuit resonating at a third frequency
Data Source
Figure 1~3
Figure 4~6
Figure 7~9
AI summary
First antenna element (1) includes a first end connected to feedpoint (11), a second end connected to connection point (P4) on ground conductor (GND), and fold (P3) disposed between the first and the second ends. A part of a segment between the first end and fold (P3) of first antenna element (1) is disposed along ground conductor (GND). Second antenna element (2) branches off first antenna element (1). Second antenna element (2) is disposed between the part of first antenna element (1) disposed along ground conductor (GND) and ground conductor (GND). The segment between the first end and fold (P3) of first antenna element (1) resonates at frequency f1. Second antenna element (2) and a segment between the first end and branch point (P2) of first antenna element (1) resonate at frequency f2 that is higher than frequency fl.