Folded Multiband Watch Antenna With Notch Filter Isolation
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Solution Overview
Problem
The challenge is to design an antenna device for a timepiece that can efficiently transmit and receive signals across multiple communication networks like Bluetooth and GPS within a limited space, while being insulated from metal parts and maintaining optimal signal strength without exceeding the watch's volume constraints.
Innovation Solution
A miniature multiband antenna structure is created using a flexible printed circuit with two separate antenna circuits, connected via a notch filter circuitry, which leverages the properties of nearby materials like metal and sapphire crystal, allowing for optimal mechanical integration and efficient signal propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If an antenna of optimal length is used for complete signal transmission/reception, then signal power is maximized, but the antenna size exceeds the limited space available in a watch case
Solution Approach 1:
The antenna is divided into multiple separate antenna circuits (first antenna circuit for Bluetooth at 2.4 GHz, second antenna circuit for GPS at 1.5 GHz) printed on the same flexible substrate. Each circuit is optimized for its specific frequency band, allowing compact integration while maintaining optimal electrical length for each communication protocol
Solution Approach 2:
The antenna circuits are printed on a flexible substrate that can be folded or bent to fit within the watch case volume. The three-dimensional folding allows the antenna to achieve its required electrical length while occupying minimal space within the two-dimensional constraint of the watch case
2Adaptability or versatility
If multiple communication devices are integrated into a single watch casing, then communication versatility is improved, but the watch size increases beyond the maximum diameter constraint
Solution Approach 1:
Multiple antenna circuits for different communication protocols (Bluetooth and GPS) are merged onto a single flexible substrate. This integration allows multiple communication functions to coexist within the limited watch case volume without requiring separate antenna assemblies for each protocol
Solution Approach 2:
The flexible substrate serves multiple functions: it acts as the structural base for both antenna circuits, provides electrical connections through its conductive traces, and can be folded to adapt to the watch case geometry. This multi-functionality reduces the overall component count and space requirements
3Volume of moving object
If an antenna is placed near metallic parts in the watch case, then space utilization is improved, but signal transmission is degraded due to interference
Solution Approach 1:
A notched filter circuit is introduced as an intermediary between the antenna circuits and the metallic parts of the watch case. This filter circuit selectively passes the desired frequency bands (2.4 GHz for Bluetooth, 1.5 GHz for GPS) while blocking interference from metallic structures and other sources, allowing the antenna to operate effectively near metallic components
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 solution enables full-power signal transmission and reception across multiple frequency bands, ensuring effective communication while fitting within the limited space of a watch, with improved impedance matching and isolation of frequency bands.
Implementation Method 1
an antenna device intended for use in a communication system to be integrated into the casing of a timepiece... comprising two separate antenna circuits... allowing for optimal mechanical integration and efficient signal propagation
Implementation Method 2
connected via a notch filter circuitry, which leverages the properties of nearby materials like metal and sapphire crystal, allowing for optimal mechanical integration and efficient signal propagation... isolation of frequency bands
Data Source
Figure 1~2
Figure 3~4
AI summary
An antenna device (1) intended for use in a communication system of a timepiece, comprising: - a substrate (10); - a first antenna circuit (11) made on said substrate and having first and second wires (110, 111) connected and having a proximal end and a distal end, extending in parallel; - a second antenna circuit (12) made on said substrate (10) and having third and fourth wires (120, 121) connected and having a proximal end and a distal end, extending in parallel; - a junction electrical link (13) joining the proximal ends of the first and third wires; - a connecting part (100) configured to be bent relative to said junction electrical link, and comprising a conductive connection connected to the junction electrical link (13) and comprising electromagnetic shielding of said conductive connection.