Linear Antenna Pair Calibration for Circular Polarization
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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 using horizontally and vertically polarized antennas to receive and transmit circularly polarized signals by generating and processing baseband signal vectors, estimating receiving polarization vectors through eigenvectors and channel estimations, and calibrating power amplifiers and local oscillator signals to minimize polarization loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If linearly polarized antennas are used in mobile terminals, then the device complexity is reduced and ease of manufacture is improved, but the ability to transmit and receive circularly polarized signals deteriorates, causing interference and reduced frequency efficiency
Solution Approach 1:
The patent divides the antenna system into two separate linearly polarized antennas (first and second antennas with orthogonal polarizations) that work together to transmit and receive circularly polarized signals. Each antenna handles one component of the circular polarization, and through signal processing combining both antenna outputs, the system achieves circular polarization capability without requiring a single complex circularly polarized antenna structure.
Solution Approach 2:
The patent makes the linearly polarized antennas multi-functional by enabling them to both transmit/receive linearly polarized signals directly and transmit/receive circularly polarized signals through coordinated operation with the orthogonal antenna. This universal capability allows the same antenna structure to serve multiple polarization modes, eliminating the need for separate specialized antennas.
2Ease of manufacture
If linearly polarized antennas are used to receive circularly polarized signals, then the manufacturing cost is reduced, but signal quality deteriorates due to polarization loss
Solution Approach 1:
The patent combines the outputs from two linearly polarized antennas (with orthogonal polarizations) through signal processing to reconstruct the circularly polarized signal. By merging the signals from both antennas with appropriate phase and amplitude adjustments, the system achieves full circular polarization reception capability, maintaining signal quality while using simpler linearly polarized antenna structures.
Solution Approach 2:
The patent implements a signal processing system that receives signals from both linearly polarized antennas, processes them through complex mathematical operations including eigenvalue decomposition and polarization vector estimation, and combines them to recover the original circularly polarized signal. This feedback-based signal processing compensates for the polarization mismatch loss that would occur with a single linearly polarized antenna.
3Ease of operation
If circularly polarized signals are transmitted using linearly polarized antennas, then device simplicity is improved, but interference between adjacent beams increases
Solution Approach 1:
The patent dynamically switches the polarization mode of the antenna system between right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP) for adjacent beams. This dynamic polarization switching is controlled based on beam identification, allowing the system to adapt its polarization characteristics to minimize interference between neighboring beams while maintaining operational simplicity through the use of fixed linearly polarized antenna structures.
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. Processing circuitry of 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.