Interference Problems on 100 MHz Band Navigation Receivers of Small Aircraft

Abstract

Since high coupling of a navigation antenna and a communication antenna on a small aircraft is almost inevitable, the interference of the emission of communication radio wave to the navigation receiver is often observed. Two sets of 100 MHz band navigation receiver and communication tranceiver are used for the study of the interference. Flight measurements are performed as well as laboratory study and the latter gives a group of curves for allowable coupling. Behaviors and interference of the navigation/communication systems are measured on the Beechcraft H-18 in the South Kanto area of Japan in order to check the results of laboratory analyses. The results show that the reassignments of frequencies should be made taking account of geographycal distribution of ground stations of aeronautical radio aids and air traffic conditions.