Choice of Power for a Radio Station

The cost of a radio station may be looked upon as the combined value of the buildings, the generating machinery, and the antenna with its masts and ground connection. It is shown in this paper that, for a given radio transmission, the necessary power P in the antenna and the effective height h of the antenna are connected by an equation P = a+bh². By means of this formula, the cost of the antenna and the masts, as a function of their dimensions, may be expressed as a function of the power, hence all the curves of cost may be combined graphically. The resulting curve of total cost clearly shows that there is some power for which the cost of a radio transmitter is a minimum. A method is also given for choice of power by which the annual expenses are a minimum. The methods described above are illustrated by a determination of the power in the antenna and the heights of the masts for a radio station with a range of 3,000 km. and operating on an optimum wave length of 5,070 m. In this instance, the power for the least outlay is 30 kw. and for the lowest annual expenses, 20 kw.