NPL time signal at Anthorn

I've been looking at these aerials every day for over 10 years but I haven't paid much attention to how they work. It occurred to me today that it isn't the masts that you can see from Wigton that transmit the waves but the wires strung between them. In the picture it is possible to see vertical wires from the ground going up in front of the most distant right hand mast. They then make a T-shaped antenna with horizontal lines. The signal must be being fed from the ground station. By making electrons in the wires vibrate, you can generate an electromagnetic wave. Such dipole antennae have a half wavelength along the top of the T. The masts are 227 metres tall. The distance between the masts is bigger than this - perhaps 500m - which would give 1000m for the shortest wavelength of LF radio waves and would give a frequency of 300 kHz. This sounds right for data on the Rugby masts which used to house the time signal. The radio waves set the time for radio controlled clocks around the country. The time itself is fixed by the NPL National Physical Laboratory in London.