Homodyne Reflectometer Phase Reference for 3D Holographic Imaging
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Solution Overview
Problem
Conventional wideband imaging systems face challenges in achieving phase referencing to the antenna aperture, especially at high frequencies, requiring complex and costly calibration processes, which is difficult and impractical for wideband frequency operation.
Innovation Solution
A homodyne reflectometer design with a standing wave probe positioned a fraction of a wavelength from the antenna aperture, providing a real-valued output signal proportional to the in-phase component of the reflected signal, eliminating the need for additional phase referencing calibration across all frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a homodyne full quadrature reflectometer is used to provide wideband vector measurement, then measurement capability is improved, but device complexity and cost increase due to requiring multiple sources, mixers, amplifiers, and filters
Solution Approach 1:
The patent extracts only the essential in-phase measurement component from the full quadrature reflectometer system, eliminating the need for quadrature signal processing while retaining the core measurement capability needed for imaging applications
Solution Approach 2:
The patent employs a simpler reflectometer design that sacrifices some measurement sophistication (full vector capability) in exchange for significantly reduced system complexity and cost, accepting that the simplified system is sufficient for the intended imaging application
2Measurement precision
If phase referencing calibration is performed for all frequencies within the band, then measurement accuracy is improved, but measurement time and operational complexity increase
Solution Approach 1:
The patent performs phase referencing calibration once at the aperture plane before measurements, establishing a reference that remains valid across the frequency band, eliminating the need for repeated calibration at each frequency
Solution Approach 2:
The patent establishes a universal phase reference at the aperture that serves all frequency measurements simultaneously, making the calibration process frequency-agnostic and applicable across the entire operating band
3Adaptability or versatility
If a heterodyning scheme is used for wideband frequency operation, then frequency range is improved, but device complexity and cost increase due to requiring multiple sources, mixers, amplifiers, and filters
Solution Approach 1:
The patent designs a reflectometer system that maintains a single consistent architecture across the entire frequency band, using the same components for both narrowband and wideband operation without requiring additional heterodyning equipment
Solution Approach 2:
The patent achieves wideband operation by adjusting operational parameters of existing components rather than changing the fundamental system architecture, allowing frequency agility without adding complexity
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
Enables robust and sensitive imaging systems capable of producing multi-dimensional profiles of objects without the need for post-measurement calibration, effectively addressing the limitations of existing systems by maintaining phase reference at the antenna aperture across a wide frequency range.
Implementation Method 1
A standing wave probe (e.g., coupler) located at a distance from the antenna aperture... sampling the reflected signal
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A holographic imaging system including a transmission line coupled to an antenna at one end and to a signal source at another end. The antenna defines an aperture through which a signal generated by the signal source is transmitted incident to an object located remotely from the aperture and through which a signal reflected from the object is received by the antenna aperture. A standing wave probe phase-referenced to the antenna aperture samples the reflected signal. A detector connected to the standing wave probe receives the sampled reflected signal and provides an output signal that represents a real-valued signal proportional to an in-phase component of the reflected signal from the object. A processor executes an imaging algorithm for generating a multi-dimensional profile representative of the object based on the output signal from the detector.