Multipath effects on low-angle tracking at millimetre-wave frequencies

The realistic multipath models described provide a powerful method for evaluating the effects of multipath interference at millimetre wave frequencies. The multipath interference simulations predicted that for targets at ranges of greater than 1 km, the use of any single multipath reduction technique will probably not be sufficient to provide the degree of multipath interference rejection required for target track and straight line (constant slope) missile track. The simulations did indicate that a combination of multipath reduction techniques, including elevated missile trajectory, offset angle track, frequency agility and angle averaging, appear to provide sizeable reductions of elevation angular errors due to multipath. While these techniques may provide sufficient angular error reduction for most terrains due to the primarily diffuse nature of multipath interference at millimetre wave frequencies, additional processing may be required when operating over flat surfaces such as asphalt or calm seas