Miniature Wire Antenna with Tunable Resonance on PCB
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Solution Overview
Problem
Conventional miniature wire antennas are difficult to implement in portable devices due to their length and inability to finely tune resonance frequency, making them unsuitable for modern devices requiring multiple frequency bands.
Innovation Solution
A miniature wire antenna design utilizing rectangular metal plates and serpentine lines on a two-layer PCB, with a tunable metal plate to adjust resonance frequency, forming an artificial transmission line structure that reduces antenna length and allows for precise tuning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the conducting line is made longer to achieve lower resonance frequency, then the resonance frequency coverage is improved, but the antenna size increases and becomes difficult to use in mobile devices
Solution Approach 1:
The antenna is divided into multiple sections: a feeding line, multiple unit elements (each consisting of a rectangular plate and serpentine line combination), and a tuning element. This segmentation allows the antenna to achieve lower resonance frequencies through multiple units in series without requiring a single excessively long conducting line, thus reducing the overall antenna length while maintaining frequency coverage adaptability.
Solution Approach 2:
The antenna structure transitions from a planar two-dimensional layout to a three-dimensional configuration by stacking rectangular plates and serpentine lines on different layers (first layer and second layer) of the PCB. This vertical dimensionality allows the conducting path to fold back on itself, effectively increasing the electrical length without proportionally increasing the planar footprint, thereby reducing the antenna's overall size.
2Length of moving object
If conventional miniature wire antenna structures are used, then the antenna size is reduced, but the resonance frequency cannot be tuned finely
Solution Approach 1:
The antenna incorporates a tuning element (a rectangular plate with an adjustable connection) that can be electrically connected or disconnected from the last unit element. This dynamic configuration allows the antenna to switch between different electrical lengths, enabling fine-tuning of the resonance frequency. The tuning element can be controlled by a switch or transistor, providing dynamic adaptability while maintaining a compact size.
3Length of moving object
If chip antenna is used to achieve smallest size, then the antenna size is minimized, but the cost increases and efficiency deteriorates
Solution Approach 1:
The antenna structure uses standard PCB fabrication techniques and common electronic components (rectangular plates, serpentine lines, switches, transistors) that can be manufactured using existing industrial processes. The design is compatible with conventional PCB manufacturing, avoiding the need for specialized chip antenna fabrication equipment. This multi-functionality approach allows the antenna to achieve compact size comparable to chip antennas while maintaining ease of manufacture and lower cost through standard industry processes.
Data Source
AI summary
A miniature wire antenna includes N rectangular metal plates located at a first layer of a PCB, a tunable metal plate located at the first layer of the PCB and N serpentine lines located at a second layer of the PCB. The positions of the N serpentine lines correspond to the positions of the rectangular metal plates. A first end of each of the serpentine lines is connected to the corresponding rectangular metal plate, and a second end of each of the serpentine lines is connected to the next rectangular metal plate. A first end of the last serpentine line is connected to the corresponding rectangular metal plate, and a second end of the last serpentine line is connected to the tunable metal plate.