Switchable Inductor Low-Band Antenna Tuning
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Solution Overview
Problem
There is a challenge in designing compact wireless communications circuitry for electronic devices that incorporates conductive structures without compromising radio-frequency performance across various operating frequencies.
Innovation Solution
The solution involves forming an antenna with a resonating element arm from a peripheral conductive housing member, incorporating a short circuit branch, a series-connected inductor and switch, and an antenna feed branch, which allows the antenna to be configured to resonate across different frequency bands by adjusting the switch's state, enabling coverage of both lower and higher communications bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a compact antenna structure is used to satisfy small form factor requirements, then the device size is reduced, but the ability to maintain satisfactory performance across a range of operating frequencies deteriorates
Solution Approach 1:
The patent implements a switchable inductor that can be dynamically adjusted between different inductance values (e.g., 0.5nH, 1nH, 1.5nH, 2nH, 2.5nH, 3nH) to change the antenna's resonant frequency. This dynamic adjustment capability allows a compact antenna structure to adapt its electrical characteristics and maintain satisfactory performance across multiple frequency bands including LTE, Wi-Fi, and Bluetooth, thereby resolving the contradiction between small size and frequency versatility.
2Ease of manufacture
If conductive structures are incorporated into the device housing, then manufacturing ease and structural integrity are improved, but radio-frequency performance is degraded
Solution Approach 1:
The patent introduces a switchable inductor as an intermediary component between the conductive housing structure and the antenna feed point. This inductor acts as a tuning element that compensates for the electromagnetic interference and signal degradation caused by the conductive housing. By adjusting the inductance value, the system can maintain proper impedance matching and resonant frequency despite the presence of conductive structures, thus preserving radio-frequency performance while allowing easy manufacturing integration.
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 allows for real-time adjustment of the antenna's frequency response, ensuring satisfactory performance across a range of communications bands, thereby enhancing the wireless communications capabilities of electronic devices.
Implementation Method 1
The antenna resonating element arm may have a shorter portion that resonates at higher communications band frequencies and a longer portion that resonates at lower communications band frequencies
Implementation Method 2
A series-connected inductor and switch may be coupled between the longer portion of the antenna resonating element arm and the antenna ground
Data Source
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AI summary
Electronic devices may be provided that contain wireless communications circuitry. The wireless communications circuitry may include radio-frequency transceiver circuitry and antennas. An antenna may be formed from an antenna resonating element arm and an antenna ground. The antenna resonating element arm may have a shorter portion that resonates at higher communications band frequencies and a longer portion that resonates at lower communications band frequencies. A short circuit branch may be coupled between the shorter portion of the antenna resonating element arm and the antenna ground. A series-connected inductor and switch may be coupled between the longer portion of the antenna resonating element arm and the antenna ground. An antenna feed branch may be coupled between the antenna resonating element arm and the antenna ground at a location that is between the short circuit branch and the series-connected inductor and switch.