Modeling and simulation of a helicopter-mounted antenna using WIPL-D

Abstract

The results obtained using WIPL-D for simulation of a seven element helicopter-mounted switched-beam antenna have been discussed. We have discussed the magnitude of the distortions caused in the antenna amplitude pattern for different rotor blade positions. We compared the results from these simulations to patterns when the main rotor and rotor hub are removed from the helicopter. This allows us to isolate the effects due to the blades and rotor from those of the rest of the helicopter airframe. As expected, the blades of the helicopter have a large impact on the pattern of the antenna. Fluctuations 10 dB in magnitude or more can be seen in the predicted patterns. Using a switching scheme that assigns a fixed coverage area to each patch element would not be the best choice because the gain performance will suffer when one of the elements experiences a drop in performance due to an obstacle. Based on the results shown, a more sophisticated switching method may be necessary since multipath degrades the performance of helicopter-mounted antennas. We have found that WIPL-D is a valuable tool throughout the process of modeling a helicopter-mounted antenna.