A microwave generator (10) having a hollow central electrode (12) with a front face including hollow emmission element (18), and having an outer electrode (14), which coaxially surrounds the central electrode (12) along an axially extending resonator section (16). The two electrodes (12, 14) define a spark gap (36) and are connected to a high-voltage source (38). An ultracompact microwave generator (10) is implemented by the high-voltage source (38) being arranged in the hollow central electrode (12) of the microwave generator (10) rather than on the outside thereof.