Reflection Measurement System with Apertured RAM
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Solution Overview
Problem
Current imaging systems, such as millimeter wave imaging systems, face challenges in accurately measuring reflection data for substances like narcotics and explosives due to non-idealities in measurement systems, which affect the precision of reflection coefficient measurements.
Innovation Solution
A free space reflection measurement system utilizing a transceiver antenna and Radar Absorbing Material (RAM) with an aperture, positioned between the antenna and the measurement region, to reduce lateral movement sensitivity and environmental reflections, improving measurement accuracy by using a test sample with calibration standards to correct for errors and precisely locate the measurement reference plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional measurement system is used without RAM, then the system is simpler, but measurement precision deteriorates due to environmental reflections and lateral movement sensitivity
Solution Approach 1:
Radar Absorbing Material (RAM) is introduced as an intermediary component between the transceiver antenna and the measurement region. The RAM absorbs electromagnetic radiation that would otherwise reflect from the environment or sample holder, eliminating spurious reflections that degrade measurement precision. The RAM with aperture serves as a mediator that allows desired radiation through while blocking harmful reflected radiation.
2Measurement precision
If RAM with aperture is introduced to reduce environmental reflections, then measurement precision improves, but device complexity increases
Solution Approach 1:
The RAM is configured with a specific aperture structure that provides different properties in different regions: the aperture region allows electromagnetic radiation to pass through to illuminate the sample, while the surrounding RAM material absorbs radiation to eliminate reflections. This local differentiation of properties enables the system to achieve high measurement precision without requiring complete redesign of the entire measurement apparatus.
3Measurement precision
If calibration standards are used without test sample combination, then calibration is simpler, but measurement precision deteriorates due to inaccurate reference plane location
Solution Approach 1:
The calibration standards are combined with the test sample in a stacked configuration during calibration measurements. This merging allows the reference plane to be accurately located at the sample surface by using the known reflection properties of the calibration standards in conjunction with the test sample. The combination enables simultaneous calibration and sample measurement, improving reference plane location accuracy.
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 system provides highly accurate reflection data across a wide range of frequencies, enhancing the ability to discriminate between substances and reducing systematic errors, thereby improving the dynamic range and precision of reflection coefficient measurements.
Implementation Method 1
The present measurement system and methods also use a Radar Absorbing Material (RAM) with a RAM aperture, which can reduce lateral movement sensitivity of a sample, reduce reflections from the surrounding environment
Implementation Method 2
illuminating the test sample with electromagnetic radiation over a predetermined frequency range, wherein the electromagnetic energy is transmitted from the transceiver antenna through the aperture in the RAM
Implementation Method 3
reflected electromagnetic radiation from the test sample returns to the transceiver antenna via the aperture
Data Source
AI summary
The present disclosure is directed to a measurement system for measuring a reflection coefficient of a test sample, including: a transceiver antenna configured to be coupled to a source of electromagnetic radiation; and a RAM positioned between the transceiver antenna and a measurement region of the transceiver antenna, wherein the RAM comprises an aperture substantially orthogonal to and substantially aligned with a transceiving axis of the transceiver antenna. A method for obtaining error correction of a measurement system and a method of measuring a reflection coefficient in a test sample are also provided.