Reduction of multiple reflection influence in microwave free-space measurements

Area of Science:

• Electromagnetics and Microwave Engineering
• Materials Science

Background:

• Multiple reflections are a primary source of error in conventional microwave free-space measurements.
• Accurate material characterization in free space is crucial for various applications.

Purpose of the Study:

• To analyze the impact of multiple reflections on conventional free-space measurement techniques.
• To propose and validate a novel method for mitigating multiple reflection errors.

Main Methods:

• Analysis of error sources in conventional free-space measurement setups.
• Development of a modified free-space method incorporating absorbing materials between the antenna and sample.
• Experimental verification using attenuation measurements of timber samples.

Main Results:

• The conventional free-space method exhibited a maximum error of 1.5 dB due to multiple reflections.
• The improved free-space setup with absorbing materials reduced the maximum error to 0.4 dB.
• Significant reduction in measurement error was demonstrated for timber attenuation.

Conclusions:

• The proposed method effectively minimizes errors caused by multiple reflections in microwave free-space measurements.
• The use of absorbing materials offers a practical solution for enhancing measurement accuracy.
• This technique is valuable for precise characterization of materials like timber.