German radio signals were decoded at Bletchley Park in England (termed Ultra intelligence), and when this revealed the intentions of the U-boats, convoys could be routed to avoid them.

He also led a team at HM Signal School that developed a practical antenna, which enabled effective high frequency direction finding systems to be installed on Royal Navy convoy escort ships.

In his authoritative book 'Hitler's U-Boat War: The Hunted, 1942–1945', the American naval historian Clay Blair Jr. refers to Struszynski's achievement of antenna design as "a breakthrough of transcendent importance."

He also states that "The popular rush to credit radar, and later codebreaking, for the defeat of the U-boat left the equally effective but less glamorous and more difficult to understand Huff-Duff in the shadows".

[6] Enigma historian Ralph Erskine ('Military Communications: from ancient times to the 21st Century') states, "An operational research report based on Ultra estimated that without shipborne high frequency direction finding, Allied convoy losses in early 1943 would have been 25 to 50 percent higher, with U-boat kills being reduced by one-third.

[8] Rohwer also notes that, during the war, the Germans, being unaware of seaborne high frequency direction finding, concluded that their U-boat failures were due to Allied radar developments.