Common Antenna for NFC and FM Signal Duplexing
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Solution Overview
Problem
Current terminal products, such as mobile phones, lack a design for a common antenna that can effectively share near field communication (NFC) and frequency modulation (FM) functions, leading to space occupation and cost inefficiencies due to separate antennas for each technology.
Innovation Solution
A common antenna is designed by connecting a winding planar coil to both a near field communication matching circuit and a frequency modulation matching circuit, utilizing resistors, capacitors, and switches to achieve signal isolation and duplexing, allowing the antenna to be shared between NFC and FM, thereby reducing space and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate antennas are used for NFC and FM, then each function can be independently implemented, but the space occupation and device complexity increase
Solution Approach 1:
The patent combines NFC and FM antenna functions into a single shared antenna structure. The planar coil antenna is designed to operate at both NFC frequency (13.56 MHz) and FM frequency (100 MHz), eliminating the need for separate physical antennas and reducing space occupation in terminal devices
Solution Approach 2:
The shared antenna is designed with multi-functionality to serve both NFC and FM purposes. By optimizing the planar coil geometry and using frequency-selective circuits, a single antenna structure achieves universal operation across different frequency bands and application scenarios
2Reliability
If separate antennas are used for NFC and FM, then each function can be independently implemented, but the device complexity and cost increase
Solution Approach 1:
The patent merges NFC and FM antenna systems into a unified structure with shared components. The planar coil serves as the radiating element for both functions, and frequency-selective switches direct signals to appropriate processing circuits, reducing overall device complexity despite maintaining independent function implementation
Solution Approach 2:
Frequency-selective circuits act as intermediaries between the shared antenna and the separate NFC/FM processing circuits. These circuits include switches and filtering networks that route signals appropriately based on frequency, enabling a single antenna to interface with multiple independent processing paths
3Area of stationary object
If a single planar coil is used for both NFC and FM, then space is saved, but signal isolation between the two functions becomes challenging
Solution Approach 1:
The patent applies frequency-selective properties to different parts of the antenna system. The planar coil geometry is optimized to have different quality factors and impedance characteristics at NFC and FM frequencies, creating local quality differences that enable frequency discrimination and reduce mutual interference
Solution Approach 2:
Frequency-selective switches and filtering circuits serve as intermediaries that isolate NFC and FM signals despite their shared antenna. These circuits selectively connect the antenna to appropriate processing paths based on the active frequency band, preventing signal leakage and interference between the two functions
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
The shared antenna solution reduces space occupation and costs while maintaining effective performance for both NFC and FM, enhancing product competitiveness by enabling simultaneous operation with proper duplexing and isolation.
Implementation Method 1
a common antenna includes an antenna coil, wherein ends of antenna feed lines of the antenna coil are respectively connected to a near field communication matching circuit and a frequency modulation matching circuit
Data Source
AI summary
Disclosed is a common antenna for near field communication (NFC) and frequency modulation (FM). The common antenna comprises an antenna coil. The antenna feed line ends of the antenna coil are connected to an NFC matching circuit and an FM matching circuit, respectively. According to the disclosure, the antenna coil is connected to the NFC matching circuit and the FM matching circuit, respectively, so as to realize that the antenna is shared by the NFC and the FM, thereby reducing the costs, saving the space, and improving the product competitiveness.