Shared-Radiator Antenna Layout for Isolation and Low SAR
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Solution Overview
Problem
Conventional terminal devices face challenges in miniaturization due to separate layouts of low-frequency and Wi-Fi antennas, which occupy significant space and result in high directivity coefficients and Specific Absorption Rate (SAR) values, limiting transmit power and user experience.
Innovation Solution
The antennas share a radiator, with filters ensuring isolation and distributed feeding to reduce directivity and SAR, allowing simultaneous operation of multiple Wi-Fi antennas with reduced space occupation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low-frequency antenna and Wi-Fi antenna are disposed independently, then antenna isolation is improved, but device area increases
Solution Approach 1:
The patent combines the low-frequency antenna and Wi-Fi antenna into a shared radiator structure. The radiator serves dual purposes: it functions as a low-frequency antenna when excited at lower frequencies and as a Wi-Fi antenna when excited at 2.4GHz or 5GHz frequencies. This merging approach reduces the overall device area while maintaining proper isolation through frequency separation and filter implementation.
Solution Approach 2:
The shared radiator is designed to perform multiple functions by operating at different frequency bands. A single radiator structure supports both low-frequency communication (e.g., NB-IoT, LTE-M) and Wi-Fi operations, making the antenna system universal and multi-functional. This eliminates the need for separate dedicated antennas for each frequency band.
2Power
If Wi-Fi antenna directivity coefficient is increased, then transmit power is improved, but SAR value increases
Solution Approach 1:
The patent employs filters to change the operational parameters of the shared radiator. By implementing band-pass filters and low-pass filters, the system controls which frequency bands are active at different times. This parameter control allows the radiator to operate as a Wi-Fi antenna with appropriate directivity when needed, while preventing excessive SAR values through frequency selection and power management.
Solution Approach 2:
Filters serve as intermediary components between the radio frequency sources and the shared radiator. These filters mediate the interaction by allowing only specific frequency bands to reach the radiator at any given time, thereby controlling the directivity and SAR characteristics. The filters act as intermediaries that enable safe and effective operation across different frequency bands.
3Productivity
If multiple Wi-Fi antennas are added for 4x4 MIMO, then communication performance is improved, but device area increases
Solution Approach 1:
The patent merges multiple Wi-Fi antenna functions into the shared radiator structure. Instead of adding four separate physical antennas for 4x4 MIMO, the system uses the shared radiator with appropriate filtering and signal processing to achieve multi-antenna performance. This approach maintains communication performance while significantly reducing the area required compared to traditional separate antenna layouts.
Data Source
AI summary
An example antenna system includes a first antenna including a strip-shaped antenna radiator. The antenna radiator has a first end and a second end. At least one of a first radiator section in which the first end is located or a second radiator section in which the second end is located is used as a radiator of a second antenna. One of two first filters is connected between the first antenna radio frequency source and an antenna feed point, and the other first filter is connected between a ground and an antenna ground point. One of two second filters is connected between the second antenna radio frequency source and at least one of the first radiator section or the second radiator section, and the other second filter is connected between the ground and at least one of the first radiator section or the second radiator section.