Abstract

This report describes the results of a field strength survey of the Band IV horizontally polarised transmissions from the Crystal Palace low-power transmitter working on a frequency of 495 Mc/s. The service area of a transmitter with an effective radiated power (e.r.p.) of 1 megawatt has been calculated from the survey measurements. A comparison was made between radiation on horizontal and vertical polarisation in Band IV. The results obtained were similar to those in Band III, namely that the value of the median field strength was substantially the same but with a greater degree of scatter on horizontal polarisation. Observation of multipath interference shows that the number of echoes visible is much greater than in Band I. At most of the sites selected for investigation echoes were visible, but the use of directional aerial substantially reduced the interference. Since a Band IV directional aerial is of compact proportions, this problem may be more easily solved than on Band I, but further investigation is required on this important point.