The occurrence of interference that causes partial loss of intelligence in air navigation signal is largely dependent on total environment around radio navigation aid systems (navaids). Directional antenna polar diagrams can be measured in horizontal or vertical mode. Usually the horizontal mode means a rotation of the test antenna in the electric or E-Plane and magnetic or H-plane for the vertical mode. This paper compares the effect that selected roofing materials have on Navaids transmission distance. To achieve this, a transmitter, a receiver and a computer to measure signal level transmitted through roofing materials at a frequency of 9.4GHz are used. The study considered effects of decra, iron, steel, aluminum, plastic and clay materials on navaids transmission distance. The study found that effects of roofing materials on transmission distance varied depending on the type of selected roofing material. Signals via plastic materials decreased with distance as those via aluminum increased with distance. However the overall effect of roofing materials on transmission distance was not significant since the received signal was within the recommended strength. Also the materials had path loss exponent factors of between 3.0 to 3.7 which meant that the rate at which the signal was propagated through these structures was significantly slower than in free space where exponent factor is 2. It is recommended that studies be directed in conducting experiments in open fields and factoring in sources of variability arising from the environment so as to relate to the actual scenario of flight navigation
Keywords: Distance, Navaids, Roofing Materials, Transmission
