Throughout the WW1, all parties to the conflict were perfecting devices for wireless telegraphy. This included ground telegraphy used primarily by infantry on the front lines to communicate with regimental headquarters. Like wireless telegraphy, it transmitted electromagnetic waves, but in this case it transmitted low frequency waves trough the ground. Stations did not require the construction of antennas. This advantage, however, to some extent limited its range to about 2 km. The stations were equipped with two approximately 50 m long wires diverging laterally. At the end of each wire was an anchor (strong nail) fastened in the ground. The transmitter transmitted electromagnetic waves through them into the ground, and the receiver received them again.