Measurements of the Interaction of Radio Waves in the Ionosphere

This paper describes measurements of radio wave interaction, in special test transmissions, between the B.B.C. transmitters at Droitwich and Lisnagarvey (N. Ireland). It is shown that the theoretical formula M=M0/[1+(n/Gy)2]½ accurately describes the dependence of the interaction modulation on the modulation frequency (n/2π). The electronic collisional frequency ν at the seat of interaction is deduced from Gv and the laboratory value of G. Investigations of the phase of the modulation are also described. The paper contains a sketch of the theory of wave interaction. There is also an addendum dealing with the possible use of wave interaction as a tool in ionospheric research.