Antennas in Walls: Performance Analysis of Microstrip Patch Antennas Designed for Internet of Paint (IoP)

TL;DR

This work designs a passive microstrip patch antenna (IP-MPA) resonant at $f_r = 150$ GHz and embedded in paint, modeled with a foam substrate ($\epsilon_s = 1.03$) and a paint superstrate ($\epsilon_p = 4.5369$), with paint thickness $h_p = 5$ mm. It extends a channel model for the Internet of Paint (IoP) to capture sub-THz propagation between buried transceivers via Direct, Reflected, and Lateral waves across air, paint, and drywall, incorporating layer properties and interface roughness. Through simulations, it identifies the lateral wave along the air-paint interface (LW-A) as the dominant, most reliable path, with an optimal transceiver orientation around $(\beta^T,\beta^R) \approx (66^{\circ},123^{\circ})$ at a burial depth of $h_A = 2.5$ mm; LW-D becomes more significant at larger depths. The results suggest that IoP-enabled wall coatings and networks could transform walls into high-speed wireless communication and sensing surfaces, enabling pervasive THz connectivity in future buildings.

Abstract

This study presents a simulated transceiver with a microstrip patch antenna (MPA) designed to resonate at 150 GHz and embedded in paint. The in-paint MPA (IP-MPA) is designed for the Internet of Paint (IoP) paradigm, which envisions seamless device communication through a paint layer on walls. This study introduces a comprehensive channel model for transceivers in paint at arbitrary depths and IP-MPA orientations. The best antenna orientations are analyzed for IoP channel performance. Extensive simulations indicate that the lateral waves, which propagate along the air-paint interface, exhibit the lowest loss, making this path the most reliable for communication between transceivers in paint. Further, the maximum received power for each propagation path, with the exception of the direct path, depends on depth. The findings suggest that the proposed network of IP-MPA-enabled transceivers for IoP has the potential to transform conventional walls into an integrated high-speed wireless communication and sensing infrastructure.

Figures (5)

• Figure 1: Simulated (a) microstrip patch antenna using Foam as the substrate to resonate at a frequency of $150$ GHz in paint, (b) IP-MPA return loss variation with the frequency, (c) gain, and (d) the directivity (which depicts the gain in the polar coordinate system), implemented using MATLAB software.
• Figure 2: IoP: Embedded microstrip patch antenna multipath communication through paint.
• Figure 3: Variation in the boresight angle for the transceivers.
• Figure 4: Total and multipath received power variation with $\beta^T$ and $\beta^R$ ($0^{\circ}-360^{\circ}$) when the MPA burial depth is $0.25$ mm.
• Figure 5: Variations in the best total received power with orientations of $\beta^T=66^{\circ}$ and $\beta^R=123^{\circ}$ compared to LW-A, RW-A, DW, RW-D, and LW-D paths with the same orientation angles.