Whenever a signal interacts with objects, it can be absorbed, reflected, transmitted, scattered, and diffracted.5 All of these different interactions can cause changes in the signal, like its intensity, frequency, phase, polarization, and direction. Furthermore, it leads to different paths in which the signal travels to the receiver, called multipath propagation. The detected RSSI at the receiver is highly affected by all of these interactions due to the different properties of the multipath components and the receiver’s sensitivity to certain properties of the signal.
Interactions between the individual multipath components impact the RSSI, too. This is caused by constructive and destructive interference, where the combination of signals leads to an amplification or attenuation of the signal.
Depending on the composition and electrical properties of objects, interactions with objects potentially alter the polarization of a signal.5 This, in turn, impacts the interaction between multipath components on the receiver side and the shape of the detected radiation patterns.
Figure 11 indicates the effect of multipath propagation and polarization alteration on the measured radiation patterns. Due to the multipath propagation, a change in orientation of the radiation patterns is visible.
Furthermore, Figure 11 shows a variation in the relative distribution of horizontally and vertically polarized signals between the different locations, indicating that the polarization of these signals have changed. The polarization alteration is especially visible at approximately 150° at location 4, where the vertically polarized signal decreases in power and the horizontally polarized signal increases correspondingly.
These figures are a prime example of why antenna diversity, i.e., integrating multiple antennas with different polarization in a device, can significantly enhance the received wireless signal strength of the device.
The reception of wireless signals propagating in an indoor environment depends strongly on the characteristics of the signal, distance between antennas, and layout of the environment. This was proven with a comparison between radiation patterns for different transmitter locations, which revealed how the RSSI and polarization can change by physically moving a wireless device within the same network.
In addition, the measurements showed that higher frequency signals suffer from more signal degradation as the distance increases between transmitter and receiver. These signals face a stronger interaction with the environment, making their wireless propagation more unpredictable and prone to distortion.
To draw clear and concise conclusions about the precise effects of objects on wireless signal propagation, a more comprehensive analysis and measurement approach is needed. Nevertheless, the research conducted in this article demonstrates that the discussed phenomena significantly affect the reception of transmitted wireless signals. It emphasizes the necessity of accounting for wireless signal propagation to ensure reliable wireless networks, not only during the design of new wireless products but also throughout the construction of environments housing wireless devices, as well as during the setup of wireless networks.
1. O. Appelman, “Ray Tracing Simulation Accuracy for Predicting Indoor Wireless Signal Reception,” pp. 1-12, 2023.
2. MegiQ BV.
4. D. M. Pozar, Microwave Engineering, 4th ed., 2012.
5. A. F. Molisch, Wireless Communications (2nd edition), 2011.