J.A. Fleming is the inventor of the Diode Bulb.

Explanation:
- The Diode Bulb, also known as the Fleming Valve, was one of the earliest vacuum tube devices and a crucial component in the development of early radio technology.
- The diode is a two-element electronic component that allows current to flow in only one direction. It consists of an anode (positive terminal) and a cathode (negative terminal).
- J.A. Fleming, a British scientist and engineer, invented the diode bulb in 1904 while working at the Marconi Company. He developed the device as a means to detect and rectify radio waves in early wireless communication systems.
- The diode bulb is essentially a vacuum tube with an anode and a heated cathode. When a high-frequency signal is applied to the anode, electrons emitted from the heated cathode flow toward the anode, creating a current. However, when the signal reverses, the electrons are unable to flow in the opposite direction due to the diode's one-way current flow property.
- This rectification property of the diode bulb was crucial for the detection of wireless telegraph signals, as it allowed for the conversion of alternating current (AC) signals into direct current (DC) signals.
- The invention of the diode bulb paved the way for the development of more advanced electronic devices, such as the triode and subsequent vacuum tubes, which played a vital role in the early days of radio broadcasting and communication systems.
- Today, diodes are still widely used in various electronic applications, including rectification, signal modulation, and power conversion.
- J.A. Fleming's invention of the diode bulb marked a significant milestone in the field of electronics and laid the foundation for the subsequent advancements in vacuum tube technology.