Design technique to reduce effects of tidal variations on an ILS glide slope system

A 330 MHz null-reference glide slope system design technique to minimise the reflecting surface variations is introduced. The runaway approach end of the site selected to test this design is over an ocean. Since the ocean forms part of the reflecting surface of the glide slope system, the tidal variations will affect the glide angle. The uniform theory of diffraction is used in the analysis and calculations are made for five tidal levels from high to low tide. The results of the simulations indicate that a glide path angle exists which is least sensitive to the tidal variations. Furthermore, this optimum angle provides smooth glide path structure.