A propagation experiment involving reflection and diffraction

Measurements of propagation at a frequency of 1090 MHz over terrain that produces specular reflection and knife-edge diffraction are in good agreement with model calculations that use images to represent the effect of reflection. A hill covered with a pine forest formed the diffracting mask, and an airport area formed the reflecting surface. Agreement between measurements and model calculations required that the diffracting knife-edge be located at treetop level. Optimum propagation into the shadow region was obtained when a maximum in the reflection-lobe pattern coincided with the mask angle.