§ 68. Mr. Onslowasked the Postmaster-General what extra height is required for the towers of a microwave radio system if the radio radius of the earth is assumed to be 0.7 times its true radius, as compared with the height required if the radio radius is assumed to equal the true radius; and what extra capital cost is involved in the construction of such towers.
§ Mr. MasonMicrowave stations are, wherever possible, situated on high ground so that tall towers are not needed. In towns, towers must be high enough to clear buildings. In both these cases, an alteration to the assumed value of the radio radius of the earth makes no substantial difference to the tower height. In open country, obstructions such as hills and trees must be cleared and this factor primarily determines the aerial heights. Assuming a radio radius of 0.7 instead 105W of unity typically increases mast height by about 7 Per cent. so that increase in capital cost is not significant.