The towers
360-foot steel towers held the transmitter antennas, with 240-foot wooden towers for receivers. The wavelength was so long that a single antenna couldn't focus a beam — instead, the system illuminated huge volumes and used multiple antennas with phase comparison to estimate direction. Accuracy was poor by modern standards (±5°) but adequate to vector fighters.
Filter rooms
Raw radar plots went to a Filter Room where WAAF plotters fused multiple radar reports with Observer Corps visual sightings, resolved duplicates and produced a single track. The filtered tracks went to Fighter Command HQ and then to sector stations, where controllers vectored squadrons. Total decision latency: about four minutes from plot to airborne intercept order.
Why the Germans missed it
The Luftwaffe knew the towers existed but underestimated their importance. Early raids targeted airfields, not radar stations. When the stations were finally attacked in August 1940, the wooden huts and steel towers were surprisingly hard to destroy and were repaired within hours. The Germans never broke the system.
Legacy
Chain Home was obsolete by 1942, replaced by centimetric-wavelength systems. But the operational concept — fused multi-sensor surveillance, central control and vectored intercept — became the template for every air defence network since, from NORAD to today's IADS.