Multi-Band PCB Antenna Design for Compact WiFi Terminals
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Solution Overview
Problem
Existing WiFi antennas are large and unable to simultaneously cover multiple frequency bands, such as 2.4GHz and 5GHz, while maintaining performance, due to size constraints.
Innovation Solution
The design includes a first antenna branch, a grounding branch, and a second antenna branch on opposite surfaces of a circuit board, with staggered sub-branches forming a gap to create a capacitance effect and an LC circuit, which reduces the overall size by presenting a left-handed transmission line effect, allowing coverage of multiple frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the antenna size is reduced to meet miniaturization requirements, then the compactness is improved, but the ability to cover multiple frequency bands deteriorates
Solution Approach 1:
The antenna is divided into multiple branches (first antenna branch with first and second sub-branches, second antenna branch) that can be independently configured to resonate at different frequencies. Each branch acts as an independent resonating element, allowing the compact antenna structure to cover multiple frequency bands simultaneously without requiring a larger overall size.
Solution Approach 2:
The first and second sub-branches are nested within the same physical space on the circuit board, with the second sub-branch positioned adjacent to and partially overlapping the first sub-branch. This nesting arrangement allows multiple resonating elements to coexist in a compact volume, enabling multi-frequency operation without proportionally increasing the antenna's physical dimensions.
2Volume of moving object
If the antenna space is compressed to reduce overall product size, then the compactness is improved, but the antenna performance deteriorates
Solution Approach 1:
Different regions of the antenna structure are designed with different electrical characteristics. The first sub-branch is optimized for 2.4GHz resonance while the second sub-branch and second antenna branch are configured for 5GHz resonance. This local optimization allows each part of the compressed antenna structure to maintain its intended function despite the overall size reduction.
Solution Approach 2:
The antenna design utilizes the third dimension (vertical stacking on opposite sides of the circuit board) to accommodate multiple resonating elements. By placing branches on both surfaces of the PCB and using vertical clearance rather than horizontal space, the design achieves multi-frequency coverage in a compact footprint without compromising performance.
3Adaptability or versatility
If a single antenna structure is used to cover multiple frequency bands, then the multi-band coverage is improved, but the antenna size increases
Solution Approach 1:
The antenna employs multiple resonating elements with different electrical lengths and configurations that can be independently activated or tuned. The first sub-branch with its specific length and grounding configuration resonates at 2.4GHz, while the second sub-branch and second antenna branch resonate at 5GHz. This dynamic multi-resonator approach enables frequency agility without requiring a single large structure.
Solution Approach 2:
The shared feed structure and common grounding system serve multiple functions by providing excitation to different branches for different frequency bands. The first feed point excites both the first and second sub-branches, while the second feed point excites the second antenna branch, allowing a single antenna structure to universally support both 2.4GHz and 5GHz WiFi bands.
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 the antenna to cover both 2.4GHz and 5GHz frequency bands with reduced size, ensuring efficient performance and compactness, while maintaining resonance frequencies and reducing electrical lengths of the antenna branches.
Implementation Method 1
the first sub-branch and the grounding sub-branch are staggered to form a gap, and the first antenna branch and the grounding branch are mutually coupled through the gap
Implementation Method 2
the first antenna branch, the grounding branch, and the first feed form a first antenna, which is configured to generate a first resonance frequency; the first antenna branch, the second antenna branch, and the first feed form a second antenna, which is configured to generate a second resonance frequency
Data Source
Figure 1a~1b
Figure 1c~2
Figure 3~4
AI summary
The present invention discloses an antenna and a terminal, where the antenna includes: a first antenna branch, printed on a first surface of a circuit board, where the first antenna branch includes a first sub-branch; a grounding branch, printed on the first surface, where the grounding branch includes a grounding sub-branch, the first sub-branch and the grounding sub-branch are staggered to form a gap, and the first antenna branch and the grounding branch are mutually coupled through the gap; a second antenna branch, printed on a second surface of the circuit board, where the second surface and the first surface are two opposite surfaces of the circuit board; and a first feed, electrically connected to the first antenna branch; where: the second antenna branch is electrically connected to a metal via hole on the circuit board, and the metal via hole is electrically connected to the first feed; the first antenna branch, the grounding branch, and the first feed form a first antenna, which is configured to generate a first resonance frequency; and the first antenna branch, the second antenna branch, and the first feed form a second antenna, which is configured to generate a second resonance frequency.