Heinrich Rudolf Hertz (1857-1894): Radio waves (1888).
Gustav Ludwig Hertz (1887-1975): Nobel 1925.
Carl Hellmuth Hertz (1920-1990): Medical ultrasonography.

[ The above copyrighted picture is reproduced here by permission:   © 2008 Jochen Wilke. ]

Quarterly. [1 & 4] Gules a harp Or.  [2 & 3]  Argent, three hearts Gules.

Crest:   A fallow stag's head Argent, armed and langued Gules.
Mantling: Gules and Argent,