Standardised Transmitting Aerials for Medium-Frequency Broadcasting

The Postmaster-General's Department has developed a range of aerial systems suitable for National Broadcasting Service transmitting stations of powers from 200 watts to 50 kilowatts in the frequency range 540-1600 kc/s. The aerial systems fall into two classes: ``high'' aerials having special anti-fading properties, usually near half-a-wavelength in height, and ``low'' aerials less than a quarter-wavelength in height. This paper traces the development of the designs, with special emphasis on low aerial systems suitable for construction by Departmental staff. Here the appllication of practices well-established at V.H.F. leads to structures believed to be novel for M.F. broadcasting. Charts and diagrams are given from which aerial structures suitable for any particular application may be readily selected.