Electrical Experimenter, September, 1918, page 316:
U.S. Signal Corps Radio Outfit in France
THE Radio Division of the U. S. Signal Corps has been wonderfully enlarged since our entrance into the great world war, and thousands of portable wireless outfits are being assembled and shipt to Europe at this time. The accompanying photograph shows one of the Signal Corps Radio Squads on duty in France, A collapsible telescopic mast is usually supplied with this apparatus so that the antenna can be raised or taken down at a moment's notice.
When the troops are entrenched in dugouts, then the radio men install their apparatus in a well protected underground cavern and lead their antenna wires from the apparatus up thru dark passageways and out to the aerial itself. In trench warfare the antenna is a low affair not extending over three to four feet above the trenches. The antenna under these conditions is given a fairly good length to make up for the low altitude.
When the army makes a rapid advance, then the radio crews move forward with the troops and carry their wireless apparatus and aerial paraphernalia on mules or horses, or still more often nowadays, on auto trucks, some of which are assigned to the radio divisions for the purpose. There are also a large number of portable wireless outfits mounted in auto trucks which can travel over the field very rapidly, and which can be put into operation in less than a minute's time. These wireless trucks carry a telescopic aerial mast made of steel tubing, and are provided with special means for quickly raising and lowering the mast.