Radar cross section from small wind turbines on top of radio cellular pylons

Hybrid-powered base transceiver stations (BTSs) have become an effective and attractive solution to reduce fossil fuel consumption, when power demand for future mobile networks (e.g. LTE/4G, 5G) dramatically increases. Such BTSs are powered by small wind turbines (SWTs) having nominal power in the range of 1.5-7.5 kW. Due to the close proximity between SWTs and BTSs, questions have been raised about possible radio interference. In the context of the OPERA-Net2 European project, the main objectives of this original work relate to study and quantify BTS/SWT compatibility as well as to propose recommendations to mitigate related disturbances. Compared to megawatt WTs, SWTs have a variety of shapes, materials and orientations (horizontal/vertical). Thus, a simple representative model (RSWT) was first designed. It is made entirely of metal to correspond to the worst case. Its dimensions are naturally related to SWT nominal power. They were then optimized to improve RCS match between the RSWT and Nheowind 3D100 (NHEOLIS - IDSUD ENERGIES) realistic model having the same nominal power. With noticeable blade shape, this model well addresses the diversity of SWTs. A scaled prototype of the 3.5 kW RSWT model with a ratio 1:10 was manufactured. Its RCS was measured in the anechoic chamber at 9 GHz and 17 GHz. Comparisons between simulation and measurement at these frequencies show good agreement. Taking into account the frequency and dimension scale factors, the simulation results obtained at radio cellular frequencies are validated.