Mediumwave radio is fussy about ground. The signal travels along the surface of the Earth, and what it travels over matters - salt water carries it far, dry rocky terrain absorbs it. When Dutch engineers needed a high-power AM site in the late 1970s, they chose a stretch of recently drained seabed near Zeewolde, in the Oostelijk Flevoland polder, because the conductivity was excellent and the land was empty. The transmitter came online in 1980, broadcasting Hilversum 1 and Hilversum 2 - the two main Dutch public radio channels of the era. The site used a sophisticated arrangement called an anti-fading aerial: a cage antenna mounted partway up two grounded masts, divided by an insulator at 95 metres. The trick let the station push its signal cleanly along the ground while suppressing the sky wave that would otherwise interfere with itself after bouncing off the ionosphere at night. The directional pattern was tilted four decibels to the southeast, compensating for the patchwork conductivity of the rest of the country.

In 1985 the Dutch public broadcaster reorganized, and the two frequencies were reassigned. NPO Radio 1 took 747 kilohertz; NPO Radio 5 took 1008 kilohertz. The 747 signal was the workhorse - news, talk, sports - and at 400 kilowatts of carrier power it carried far. Truckers heard it crossing into Germany. Sailors picked it up in the southern North Sea. Cars on French motorways could still find it on summer evenings when the skip was right. In 2003 the government auctioned off 1008 kHz to commercial operators; the channel passed through Radio 10 Gold and then to Groot Nieuws Radio, a small religious station that pushed Dutch-language Christian programming out across the same listening area. NPO Radio 5 held 747 kHz for another decade, but the audience was draining away to FM, DAB, and streaming. In June 2013 NPO announced what everyone already knew: mediumwave was done.

At two minutes past midnight on 1 September 2015, the 747 kHz transmitter near Zeewolde - and the 1251 kHz transmitter at Lopik that had partnered it for decades - went silent. NPO had chosen the small hours deliberately. There was no countdown, no final message, just the carrier dropping out and the noise of static rushing in to fill the gap. The Dutch public broadcasters' eighty-six years of AM transmission ended at that moment. Groot Nieuws Radio kept 1008 kHz alive from the same site, but at reduced power - 100 kilowatts instead of 400 - and even that ended on 31 December 2018, when the station moved entirely to digital and online. For ten days the masts stood completely silent. Then the demolition crew arrived.

The two 195-metre masts were among the tallest structures in the country at the time of their demolition, surpassed mainly by the Gerbrandy Tower at IJsselstein and a handful of newer wind turbines. Their footprint on the polder is now a flat field bordered by a low service road called the Vogelweg. The ground anchors remain, weathering into the soil. The substation that fed them with 400 kilowatts has been decommissioned. Local birders sometimes stop at the spot because shorebirds favour the open grass, and amateur radio operators occasionally come to photograph the empty sky where the antennas used to be. The whole episode is a particularly Dutch story: a piece of infrastructure built to last, used precisely as long as it was useful, and then deliberately and tidily removed when the technology underneath it changed. Mediumwave is now functionally extinct in the Netherlands. The radios that received it still work; they just have nothing left to find.