Capacitor-Loaded Slot Antenna for Multi-Band Metal Watch Casings
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Solution Overview
Problem
Smart wearable devices with all-metal casings face challenges in designing slot antennas that can effectively cover multiple frequency bands due to limited design spaces and the need for shorter slot lengths to accommodate smaller volumes.
Innovation Solution
The implementation of a multi-frequency slot antenna with a capacitor positioned to adjust resonance frequencies, allowing for a shorter physical slot length while maintaining effective electrical length, enabling the antenna to cover multiple frequency bands such as GPS L5 and Bluetooth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the slot length is reduced to accommodate smaller device volume, then the device volume is reduced, but the antenna cannot cover multiple frequency bands
Solution Approach 1:
The patent changes the electrical parameters of the slot antenna by introducing capacitive loading. The capacitor modifies the resonant frequencies of the antenna, enabling it to support multiple frequency bands (GPS L1, L5, and Bluetooth) despite the physically shortened slot length. This parameter change allows the antenna to maintain multiple resonant modes within a compact structure.
Solution Approach 2:
The capacitor serves as an intermediary element that couples to the slot antenna and modifies its electrical characteristics. By introducing this intermediate component, the antenna's resonant frequencies are adjusted to cover multiple bands without requiring a longer physical slot, thus resolving the contradiction between compact size and multi-frequency capability.
2Length of stationary object
If the slot length is reduced to fit in limited design space, then the design space constraint is satisfied, but the effective electrical length is insufficient for multi-frequency operation
Solution Approach 1:
The capacitor loading changes the electrical parameters of the slot, effectively increasing the electrical length without proportionally increasing the physical length. The capacitive reactance introduces additional phase shift, allowing the wave to accumulate the necessary electrical length over a shorter physical distance, enabling multi-frequency resonance in a compact slot.
3Adaptability or versatility
If a longer slot is used to achieve multi-frequency resonance, then the frequency band coverage is improved, but the device volume increases
Solution Approach 1:
Instead of increasing physical slot length to achieve multi-frequency coverage, the patent changes the electrical parameters through capacitive loading. This allows the same physical slot to support multiple resonant frequencies by modifying its electrical characteristics, thereby achieving frequency band coverage without increasing device volume.
Solution Approach 2:
The capacitive loading enables the single slot antenna to perform multiple functions by supporting multiple resonant modes. The same physical structure can operate at GPS L1, L5, and Bluetooth frequencies simultaneously or independently, making the antenna universal for multiple communication standards without requiring separate antennas or a larger structure.
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 allows for the realization of dual-band GPS and Bluetooth antennas in smart watches with limited volume, enriching device functions and improving user experience by effectively extending the antenna's effective electrical length without increasing the physical size.
Implementation Method 1
a capacitor provided in the slot, two electrodes of the capacitor being respectively connected to two sides of the slot in a width direction of the slot
Implementation Method 2
lengths of the slots for generating electromagnetic resonances are generally half of the first-order resonance wavelengths
Data Source
AI summary
Described are electronic devices, and specifically provides a multi-frequency slot antenna, a terminal device and an antenna resonance frequency adjustment method. The antenna is applied to a terminal device, and the terminal device includes a metal casing. According to an example, the antenna includes a slot provided in the metal casing, the slot having a first end and a second end opposite to each other in a length direction; a feed terminal across inside of the slot and located between the first end and the second end; and a capacitor provided in the slot, two electrodes of the capacitor being respectively connected with two sides of the slot in a width direction. Furthermore, in the length direction, the capacitor is located at a position where voltages are not zero at original values of multiple orders of resonance frequencies of the antenna when the capacitor is not provided in the slot. In this way, an operating frequency of the antenna includes multiple orders of resonance frequencies.