Blade horn

A shaped bar horn or flatted-cylindrical horn where the output cross-section is rectangular but of smaller area than the input cross-section, thereby imparting gain to the horn. (In this connotation, "blade" does not indicate any cutting ability although a blade horn may be designed for such ability.)

Scotto[3] (Mecasonic) refers to this as "pelle" (shovel or spade).

Also see blade.