Abstract
AbstractElectromagnetic (EM) reflection properties of building materials and structures have been investigated through practical measurements. However, the finite thickness of measured materials makes it challenging to resolve the rays reflected from the front and the back surfaces. In this paper, we therefore present a three‐step minimum least squares‐based algorithm to resolve two closely adjacent rays reflected from the front and the back surfaces of a board‐shaped material. Our analytical and numerical results show that the proposed algorithm achieves the Cramér‐Rao lower bound. The proposed algorithm is validated using measurement data for various materials and incident angles in the 40–50 GHz frequency band. The validation results show that the proposed algorithm is capable of resolving two closely adjacent rays with a root‐mean‐square deviation that is smaller than 0.08. Main applications of the proposed algorithm can be found in the frequency domain measurements of the EM wave reflections by typical building structures, e.g., window glass, doors, ceiling, and floors.
Highlights
Over 80% of mobile traffic takes place indoors, and it is predicted that mobile traffic will increase by up to 1,000 times in the decade (Cisco, Accessed Accessed 2019)
For low the power of high-order reflections and other multipath components in the measurement environment, i.e., σm2, the proposed algorithm has an mean square error (MSE) that is close to the Cramér-Rao lower bound (CRLB)
A three-step minimum least squares (MLS)-inspired algorithm to resolve two adjacent rays for board-shaped material EM property measurement is proposed with the assumption that powers of the main reflection and the first-order internal reflection are much greater than that of the combination of high-order reflections, multipath components in the measurement environment, and measurement noise
Summary
Over 80% of mobile traffic takes place indoors, and it is predicted that mobile traffic will increase by up to 1,000 times in the decade (Cisco, Accessed Accessed 2019). An alternative way to simulate reflections by board-shaped building materials is to simulate the two main closely adjacent rays, whose behavior needs to be characterized through measurement. We focus on the characterization of the spatial resolution of the two-ray reflection model from planar building materials in the VNA-based measurement. We propose a three-step minimum least squares (MLS)-based algorithm to resolve two adjacent rays reflected from the front and the back surfaces of a board-shaped material. Comparisons between the CRLB and measurements show that the proposed algorithm is capable of resolving two closely adjacent rays with an excellent accuracy.
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