Wooden Lattice Masts

For radio work, the use of wooden guyed structures is advocated on the grounds that they are inexpensive and suited to the doubtful permanency of some radio stations. The horizontal pull of the antenna at the top of the masts is assumed to be about 14,000 kg. (30,000 lbs.); thus taking account of wind pressure, ice covering of the antenna wires, and the tension due to elimination of wire sag. The antenna should be guyed at a number of points to avoid long spans with high stresses due to beam and column action. The use of many light guys is advisable because of the difficulty of breaking up heavy guys by insulators. The position of the anchorages is determined by considerations of guy economy and of value of surrounding land. In calculating wind stresses, an assumed wind load on the masts of 200 kg. per sq. meter (40 lbs. per square foot) is used; and about 0.8 to 0.9 of the mast surface is regarded as effective in opposing the wind. The load at the center of each span is equal to the dead weight of the masts above added to the stresses due to beam and long column action. This load enables calculating the cross section of the masts. For masts up to about 100 meters (300 feet) high it is recommended to use only one size of timber to avoid complication. Above that height, a second lighter timber may be used.