'Mandrel' was a British electronic countermeasures operation carried between Littlehampton in Sussex and Portland Bill in Dorset (5/6 June 1944).

The undertaking was handled by aircraft of Air Vice Marshal E. B. Addison’s No. 100 Group of the RAF to spoof and degrade the performance of the German 'Freya' and 'Würzburg' radar installations on the southern side of the English Channel in support of 'Neptune' (iii) and 'Overlord'.