Metal-Frame Circularly Polarized Antenna for Compact Terminals
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Solution Overview
Problem
Existing terminal electronic devices use linearly polarized antennas, which are not suitable for satellite communication or navigation due to polarization mismatch, leading to energy loss. Additionally, integrating circularly polarized antennas into these devices is challenging due to industrial design constraints and the need for a compact form factor.
Innovation Solution
A built-in circularly polarized antenna structure using a metal frame as a radiator, which achieves circular polarization in a small-clearance environment. The antenna is designed to have two orthogonal polarization modes within a specific frequency band, ensuring an axial ratio of circular polarization is less than or equal to 10 dB.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a linearly polarized antenna is used in terminal electronic devices, then the device structure is simple and compact, but polarization mismatch occurs in satellite communication leading to energy loss
Solution Approach 1:
The patent combines two linearly polarized antennas (first and second linear antennas with orthogonal polarization directions) into a single integrated antenna system. By merging these two antennas and using a feed network to provide signals with a 90-degree phase difference, the system generates circularly polarized waves, thereby reducing polarization mismatch loss in satellite communication while maintaining structural compactness.
Solution Approach 2:
The integrated antenna system serves multiple functions: it can operate as two separate linearly polarized antennas for general communication, and simultaneously function as a circularly polarized antenna for satellite navigation and communication. The feed network can selectively provide signals to different antenna combinations based on communication requirements, making the antenna system universally applicable to different communication scenarios.
2Loss of energy
If an external circularly polarized antenna is used for satellite communication, then polarization mismatch is avoided, but the device volume increases and built-in integration cannot be implemented
Solution Approach 1:
The patent embeds the circularly polarized antenna system within the terminal device's internal structure. The first and second linear antennas are integrated into the device housing, and the feed network is incorporated into the internal circuit board. This nesting approach allows the circularly polarized antenna to be built-in rather than external, reducing device volume while maintaining the ability to generate circularly polarized waves for satellite communication.
Solution Approach 2:
The patent changes the operational parameters of the antenna system by controlling the phase and amplitude of signals fed to the linear antennas. By adjusting the phase difference to 90 degrees and maintaining equal amplitudes, the system transforms linearly polarized radiation into circularly polarized radiation, thereby achieving the desired polarization characteristics without increasing physical volume.
3Area of stationary object
If the frequency spacing between first and second resonances is reduced, then the operating frequency band widens, but the axial ratio performance may deteriorate
Solution Approach 1:
The patent employs adjustable reactive components (inductors and capacitors) in the feed network to dynamically optimize the axial ratio across the operating frequency band. These components can be tuned to compensate for variations in the frequency spacing between resonances, maintaining precise axial ratio performance (less than 3 dB) even when the operating bandwidth is expanded by reducing frequency spacing between the first and second linear antennas.
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 solution enables efficient satellite communication and navigation in terminal electronic devices by minimizing energy loss due to polarization mismatch and allowing for compact integration of circularly polarized antennas.
Implementation Method 1
The antenna is configured to generate a first resonance and a second resonance. A ratio of a frequency of the first resonance to a frequency of the second resonance is greater than 1 and less than or equal to 1.5. An operating frequency band of the antenna includes a first frequency band, and a frequency in the first frequency band is between the frequency of the first resonance and the frequency of the second resonance.
Implementation Method 2
An axial ratio of circular polarization of the antenna in the first frequency band is less than or equal to 10 dB. In the first frequency band, the antenna may implement circular polarization through the two orthogonal polarization modes
Data Source
AI summary
An electronic device includes a conductive frame and an antenna. A part of the frame is used as a radiator of the antenna. The antenna is used to generate a first resonance and a second resonance. A ratio of a frequency of the first resonance to a frequency of the second resonance is greater than 1 and less than or equal to 1.5. An operating frequency band of the antenna includes a first frequency band, and a frequency in the first frequency band is between the frequency of the first resonance and the frequency of the second resonance.