WSN Sensor Node Antenna Performance Under Fallen Leaves

In this paper, a study on the performance of a small sensor node antenna when covered with fallen leaves, is presented. Firstly, the Wireless Sensor Network (WSN) sensor node (SN) antenna considered for this work is being introduced. The antenna was already optimised in past author’s work and is being used herein for a comparative analysis. Performance analysis is then carried out in four different scenarios considering: the effects of the soil in the surroundings of the antenna and, the partial coverage of the antenna by pine tree leaves (i.e. pine needles) and Alfalfa leaves, considering 10% and 75% of moisture content. This study is performed via electromagnetic simulation using a full-wave electromagnetic solver (CST MWS) by means of antenna matching and radiation pattern characterisation. Finally, experimental results obtained on the field are also presented, for the case when the antenna is covered by pine leaves. According to both the simulation and measurement results, it is possible to conclude that the discarded leaves, negatively impact the performance of the antenna, generating shifts on the resonating frequency and typically reducing the overall gain of the antenna. The moisture content of the leaves also impact the antenna performance, specially for higher moisture content leaves.