Phased-Array Antenna Signal Processing for Broadband Weak-Wave Detection
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Solution Overview
Problem
Current microwave radiometers face issues with mechanical parts deterioration, limited spatial resolution, narrow frequency band observation, and increasing radio frequency interference, which affect their operational life and effectiveness.
Innovation Solution
A phased-array antenna device with a configuration of antenna elements and signal processing units that perform Fourier transforms and cross-spectrum calculations, eliminating redundancy and using dual-ridged or quad-ridged feed horn antennas for broad frequency bands, and shifting sampling clock timing to achieve high spatial resolution and ultra-wideband observation without mechanical parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a rotating reflector is used to perform scans, then the microwave radiometer can observe the Earth's surface, but the mechanical parts deteriorate with age which shortens the operating life
Solution Approach 1:
The patent replaces the mechanical rotating reflector system with an electronic phased array antenna system. Instead of physically rotating a large reflector to scan the Earth's surface, the invention uses multiple antenna elements arranged in an array that electronically steer the beam by controlling the phase and amplitude of signals from each element. This eliminates all moving parts while maintaining the scanning capability, thereby solving the problem of mechanical deterioration and extending operating life.
2Measurement precision
If a larger reflector is used to improve spatial resolution, then the spatial resolution improves, but the size of the reflector is limited because of its rotation
Solution Approach 1:
The patent divides a large reflector into multiple smaller antenna elements arranged in a phased array configuration. Instead of using one large rotating reflector, the invention employs numerous small antenna elements (e.g., 10x10 or 20x20 elements) that work together through coherent signal combination. This segmentation allows achieving high spatial resolution equivalent to a large aperture while avoiding the mechanical constraints of a single large rotating reflector.
Solution Approach 2:
The patent transitions from a one-dimensional rotation mechanism to a two-dimensional array structure. By arranging antenna elements in a planar array and controlling their phases independently, the system achieves beam steering in multiple directions without physical rotation. This dimensional change enables high spatial resolution while eliminating the size limitations imposed by mechanical rotation constraints.
3Adaptability or versatility
If multifrequency receivers with horn antennas are used, then the receivers can operate at specific frequencies, but most frequency bands cannot be observed because each receiver's frequency band is narrow
Solution Approach 1:
The patent makes the antenna system universal across multiple frequency bands by using broadband antenna elements and frequency-independent phased array techniques. The same antenna array structure and signal processing methodology can observe across L-band, C-band, X-band, and other microwave frequency ranges. This eliminates the need for separate horn antenna receivers for each frequency band, achieving multi-frequency coverage with a single versatile system.
Solution Approach 2:
The patent merges multiple narrowband receiver functions into a single broadband phased array system. Instead of having separate horn antenna receivers for different frequency bands, the invention combines multiple antenna elements into an array that can simultaneously or sequentially observe across wide frequency ranges through electronic beamforming and signal processing, thereby reducing overall system complexity while expanding frequency coverage.
4Duration of action of stationary object
If a phased-array antenna device is used to eliminate mechanical parts, then the operating life increases, but the device complexity increases due to signal processing requirements
Solution Approach 1:
The patent performs preliminary signal processing at each antenna element by combining signals coherently with appropriate phase weighting before further processing. By pre-processing the signals from individual elements with calculated phase and amplitude weights, the system simplifies subsequent beamforming and spectral analysis operations. This preliminary action reduces the computational burden of the overall signal processing while maintaining the ability to achieve high spatial and spectral resolution.
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 achieves long operational life, high spatial resolution, and broad frequency band observation, reducing the impact of radio frequency interference, while minimizing mechanical components and signal processing redundancy.
Implementation Method 1
a first antenna element that receives a microwave signal
Implementation Method 2
a first preamplifier that amplifies the signal from the first antenna element
Implementation Method 3
a first band-pass filter (BPF) that passes only signals from the first preamplifier that are around a predetermined frequency
Implementation Method 4
a first A/D converter that converts the analog output signal of the first BPF into digital data
Implementation Method 5
a first FFT that performs a Fourier transform on data from the first A/D converter
Implementation Method 6
a first cross-spectrum calculation unit that multiplies the data from the first FFT by the data output by the second FFT for the same complex frequency component
Data Source
AI summary
A phased-array antenna device with a long operating life without mechanical parts, has a high spatial resolution, and realizes microwave observation of broadband and high-frequency resolution. The phased-array antenna device performs direct A/D conversion through a BPF on an antenna analog signal amplified by an amplifier. Then, the device performs a second cross-spectrum calculation after conversion into complex frequency data through FFT. To detect a weak electromagnetic wave, the device repeatedly performs a second FFT over a long period and lastly performs integration.