I don’t think that there are many examples of regional stations which target an audience in two countries? But feel free to drop a comment if you know one. Anyway, Radio Seefunk, or better Das Neue Radio Seefunk is tuned into by some 147000 German and 35000 Swiss listeners.
The station started as a local radio for the city of Konstanz under the name Seefunk Radio Bodensee. Today they have 13 transmitters across the south of Baden Württemberg in Germany. Rebranded to Das Neue Radio Seefunk in 2019 they bring music from “Vier Jahrzehnten” (4 decades) targeting an 30+ audience.
I received them while staying near Ulm. Mr. Grunewald was so kind to confirm my report sent to redaktion(at)radio-seefunk.de .
