Loop Antenna Inductor Tuning for FM Radiation Efficiency
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Solution Overview
Problem
Conventional FM antennas in electronic devices face challenges in achieving efficient radiation performance due to their electrically short length, which results in low radiation efficiency and interference with cellular and non-cellular bands, especially when integrated into conductive housings that block or deteriorate the antenna's performance.
Innovation Solution
The design incorporates a conductive cover and a ground plane with strategically placed inductors and capacitors to create a full wavelength loop antenna, shifting the electrical field distribution and reducing unwanted resonances, thereby enhancing radiation efficiency and isolation between antennas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional FM antenna is used in electronic devices, then FM transmission capability is provided, but radiation efficiency is low and interference with cellular and non-cellular bands occurs
Solution Approach 1:
The antenna structure is segmented into multiple conductive portions (first conductive portion, second conductive portion, third conductive portion) that form a loop configuration. This segmentation allows the antenna to achieve resonant frequencies that improve radiation efficiency while reducing interference with other bands through controlled current distribution in each segment.
Solution Approach 2:
The patent changes the geometric parameters of the antenna structure by forming a loop configuration with specific conductive portions and gaps. The loop structure with controlled perimeter and area creates resonant frequencies that enhance radiation efficiency at FM bands while suppressing harmonics that cause interference with cellular and other non-cellular bands.
2Reliability
If an FMTx antenna with full loop or half loop configuration is integrated into conductive housings, then FM transmission capability is achieved, but performance is blocked or deteriorated
Solution Approach 1:
The patent introduces capacitive elements as intermediaries between the conductive portions of the antenna and the conductive housing. These capacitive gaps allow the antenna to couple electromagnetically with the housing structure rather than being electrically blocked, transforming the housing from a shield into part of the resonant structure, thereby improving radiation efficiency.
Solution Approach 2:
The antenna structure combines conductive portions with capacitive elements to create a composite resonant system. This composite structure interacts with the conductive housing to form a coupled resonant system that enhances FM radiation efficiency while maintaining isolation from interference with other frequency bands.
3Reliability
If the antenna length is increased to achieve better radiation performance, then radiation efficiency improves, but device size increases
Solution Approach 1:
The patent transitions from a linear monopole antenna configuration to a planar loop configuration. This dimensional change allows the antenna to achieve resonant frequencies and improve radiation efficiency within a compact planar footprint, reducing the overall device volume while maintaining or improving radiation performance through the loop's enclosed area.
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 improves radiation performance by concentrating the electrical field and reducing interference with cellular and non-cellular bands, achieving better efficiency and isolation, while also simplifying the antenna structure and reducing costs.
Implementation Method 1
The at least two tuning inductors are configured to move an electrical field along the first length and/or the second length
Implementation Method 2
The cover, the ground plane, the first inductor, and the second inductor are configured to provide a loop radiator
Data Source
AI summary
In accordance with one example embodiment of the present invention an apparatus is disclosed. The apparatus includes a cover, a ground plane, a first inductor, and a second inductor. The cover includes a first end and an opposite second end. The cover is configured to operate as a first loop radiator portion. The ground plane is proximate the cover. The ground plane is configured to operate as a second loop radiator portion. The first inductor is proximate the first end of the cover. The second inductor is between the second end of the cover and the ground plane. The cover, the ground plane, the first inductor, and the second inductor are configured to provide a loop radiator.