Correlation in VHF propagation over irregular terrain

A study has been made of the correlation in transmission loss observed over irregular-terrain paths. Simultaneous mobile measurements were made of two pairs of VHF broadcasting stations in the Washington, D. C-Baltimore, Maryland area. The correlation coefficients derived from sample sets of transmission loss data indicate that when reception is from opposite directions, no significant correlation is evident, and when the paths of propagation are the same even though the frequencies are separated considerably, the correlation appears to be significantly high.