Linear Antenna Calibration for Circular Polarization Links
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Solution Overview
Problem
Mobile terminals with linearly polarized antennas are unable to efficiently transmit and receive circularly polarized signals, leading to interference and reduced frequency efficiency in satellite communication systems.
Innovation Solution
A method and apparatus that utilize horizontally and vertically polarized antennas to receive and transmit circularly polarized signals by generating and estimating a receiving polarization vector based on baseband signal vectors, and calibrating power amplifiers and local oscillator signals to minimize polarization loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mobile terminals use linearly polarized antennas to transmit and receive signals, then the device complexity is reduced and ease of manufacture is improved, but the ability to communicate with circularly polarized satellite signals is lost, causing polarization loss and reduced communication reliability
Solution Approach 1:
The patent segments the signal processing function by separating polarization detection from the antenna structure itself. Linearly polarized antennas are used for reception, while polarization detection is achieved through digital signal processing of the received baseband signals, dividing the polarization handling into antenna segment (linear polarization) and processing segment (polarization detection and correction).
Solution Approach 2:
The patent introduces an intermediary polarization detection and correction mechanism that mediates between the linearly polarized antenna reception and the circularly polarized satellite signal. The baseband processing unit acts as an intermediary to detect polarization state and apply correction algorithms, enabling compatibility between linear antennas and circular polarization signals.
2Device complexity
If linearly polarized antennas are used in mobile terminals, then device complexity is reduced, but interference between signals increases and frequency efficiency decreases
Solution Approach 1:
The patent implements feedback mechanisms where the received signal characteristics are continuously monitored and used to adjust polarization correction parameters. The baseband processing unit provides feedback on polarization state detection, enabling dynamic adjustment of correction algorithms to maintain optimal frequency efficiency while using simple linearly polarized antennas.
Solution Approach 2:
The patent changes the parameter domain by moving polarization handling from the physical antenna structure to the signal processing domain. Instead of changing antenna polarization physically, the system changes signal parameters through digital processing, allowing flexible polarization adaptation without increasing hardware complexity.
3Reliability
If circularly polarized antennas are used in satellites, then the ability to transmit circularly polarized signals is improved, but the complexity of the satellite communication system increases when interfacing with linearly polarized mobile terminals
Solution Approach 1:
The patent extracts the polarization detection and correction functionality from the overall system complexity and places it in the mobile terminal's baseband processing unit. This separation allows satellites to maintain their circularly polarized transmission capability while the complexity of interfacing with linearly polarized terminals is extracted and handled locally in the terminal device.
Data Source
AI summary
Provided is an apparatus for transmitting a circularly polarized signal by linearly polarized antennas. A horizontally polarized antenna and a vertically polarized antenna of the apparatus receives a first circularly polarized signal transmitted based on a transmitted baseband signal vector. Based on the first circularly polarized signal, a radio frequency (RF) module of the apparatus generates a received baseband signal vector including a product of the transmitted baseband signal vector and a receiving polarization vector of the transmitted baseband signal vector. The apparatus estimates the receiving polarization vector based on the received baseband signal vector and calibrates power amplifiers (PAs) and local oscillator (LO) signals of frequency converters in the RF module based on the estimated receiving polarization vector. The horizontally and vertically polarized antennas transmit a second circularly polarized signal based on the calibrated PAs and the calibrated LO signals of the frequency converters.