Phased-Array Antenna Signal Chain for Broad Microwave Observation
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Solution Overview
Problem
Current microwave radiometers face issues with mechanically movable components leading to shortened lifespan, limited spatial resolution due to mirror size constraints, narrow frequency bands, and increasing interference from radio frequency interference (RFI) affecting observation capabilities.
Innovation Solution
A phased-array antenna device utilizing dual-ridged or quad-ridged feed horn antennas with digital signal processing, including preamplifiers, band-pass filters, A/D converters, FFTs, and cross-spectrum calculation units, eliminating redundancy and achieving broad frequency and high spatial resolution without mechanically movable parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a rotating reflecting mirror is used for scanning, then spatial resolution can be improved by increasing mirror size, but the device complexity and mechanical wear increase, shortening operating lifespan
Solution Approach 1:
The patent replaces the mechanical rotating mirror system with an electronic phased array antenna system. Multiple antenna elements are arranged in a specific geometric pattern and use electronic beam steering to achieve scanning without any moving parts. This eliminates mechanical wear while maintaining high spatial resolution through precise electronic control of signal phases and amplitudes across the antenna array.
Solution Approach 2:
The patent divides the single large mirror function into multiple smaller antenna elements arranged in a phased array. Each antenna element contributes to the overall beam forming capability, and through coherent integration of signals from multiple elements, the system achieves equivalent or superior spatial resolution without requiring a single large mechanical component.
2Measurement precision
If horn antennas are used for each frequency band, then frequency-specific observation is enabled, but the frequency band coverage is narrow and many frequency bands are excluded
Solution Approach 1:
The patent employs broadband antenna elements that can operate across multiple frequency bands simultaneously, replacing the need for separate horn antennas for each frequency band. The phased array system processes signals from these universal antennas through digital signal processing to achieve frequency-specific analysis while maintaining broad frequency coverage.
Solution Approach 2:
The patent uses digital signal processing techniques including Fast Fourier Transform (FFT) to analyze signals across different frequency components from the broadband antenna elements. By changing the processing parameters and applying frequency domain analysis, the system can extract information from multiple frequency bands using the same physical antenna hardware.
3Device complexity
If mechanical scanning is used, then simple antenna structure is maintained, but the receiving area is limited by the mirror size
Solution Approach 1:
The patent segments the receiving function into multiple distributed antenna elements that form a phased array. This segmentation allows the system to achieve an effective receiving area equivalent to or larger than a single large mirror while maintaining relatively simple individual antenna structures. The collective arrangement of multiple elements provides the necessary aperture area.
Solution Approach 2:
The patent transitions from a two-dimensional mirror surface to a three-dimensional phased array configuration. By arranging antenna elements in multiple dimensions and using electronic beam steering, the system effectively increases the receiving aperture without requiring a single large planar surface, thus expanding the receiving area while keeping individual components simple.
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 phased-array antenna device provides high spatial resolution, broad frequency observation, and extended lifespan by digitizing signal processing, effectively overcoming RFI interference and eliminating the need for mechanically movable components.
Implementation Method 1
a phased-array antenna device that receives microwaves
Implementation Method 2
a first preamplifier that amplifies a signal obtained from the first antenna element
Implementation Method 3
a first BPF that passes only a signal in a predetermined frequency band from an output signal of the first preamplifier
Implementation Method 4
a first A/D converter that converts an output signal of the first BPF into digital data
Implementation Method 5
a first FFT that performs a Fourier transform on data output from the first A/D converter
Implementation Method 6
a first cross-spectrum calculation unit that multiplies output data of the first FFT and output data of the second FFT for the same complex frequency component
Data Source
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AI summary
The present invention provides a phased-array antenna device 101 that has a long operating lifespan achieved without using a mechanically movable component, has high spatial resolution, and realizes microwave observation of a broad band and high frequency resolution. The phased-array antenna device 101 performs direct A/D conversion through a BPF on an antenna analog signal amplified by an amplifier. Then, the device performs cross-spectrum calculation after conversion into complex frequency data through FFT. In order to detect a weak electromagnetic wave, the device repeatedly performs FFT over a long period of time and lastly performs integration.