Stp193 Neckarsulm is a ‘Y-Station’ radio guidance site located inland between Boulogne and Calais and features around 16 concrete buildings – most of which can still be seen today.
The site, near Boursin, was built to host a series of bunkers which supported large antennas for the Y-Verfahren system which beamed a single radio signal to German fighters in the air to help them calculate the position of their aircraft in order to intercept Allied bombers.
This system was an upgrade of the X-Verfahren developed in the early 1930s but used a lower frequency and was created for improved range and accuracy. This system was accurate to around 250km distance and two similar sites were built to give the system wide coverage of the occupied areas of Northern France.
Like many of the German technological radio and radar advances however it was quickly rendered obsolete by Allied counter measures.
The Boursin Y-Station site featured five ‘Sendstations’ for broadcasting the signal and all five can be seen at the location today along with two receiver bunkers which picked up the bounced-back signal from the aircraft.
With five Sendstations, five fighters could be kept in contact with at any one time, and these Y-receiver equiped aircraft would be part of a larger formation, passing on the target information to the rest of the group.
Along with the sending and receiving buildings, Stp193 Neckarsulm also features personnel shelters, generator buildings, and a water reservoir. Inside one of the Sendstations you can still see original wall coverings and wiring. On of the receiver bunkers has been used to explode left-over ammunition but inside there are still parts of the aerial visible.
Most of the site is on private farmland and so permission must be sought before visiting the bunkers.