Then Hertz proved Maxwell's prediction with a series of experiments from 1887 to 189 1.

The most famous thing is that he invented the spark intermittent transmitter, dipole transmitting antenna and half-wave resonant ring receiving antenna, which constituted the first radio link in human history.

Hertz was the first radio/RF engineer.

Later Marconi was inspired by Hertz and thought of using Hertz system for wireless communication.

He, Rocky, geek nikola tesla and others developed the tuning circuit in 1900.

At the same time, Danish engineers invented the negative resistance LC sine wave oscillator, so there was a basis for amplitude modulation.

The first AM broadcast was born in 1906.

Marconi is called the father of radio.

John. A. Fleming made the early vacuum tube in 1904.

That is, Fleming vacuum tube, which is the originator of vacuum diode. It only allows current to flow in one direction.

Then at 1907, Lee Deforest added a grid to the vacuum tube. This device with control electrodes can amplify weak signals-vacuum triode was born and the wave of electronics reform began.

Then-Armstrong, the most talented radio/RF engineer in history, began to invent in 19 12.

A series of communication circuit systems, such as regenerative receiver, superheterodyne receiver and superheterodyne circuit, are also dominant today and developed by Armstrong.

Unfortunately, this genius was caught in a lawsuit related to circuit patent technology in his later life, 1954 committed suicide at the age of 63.

Transistors were not born in Bell Laboratories until 1947.

The idea of the origin of radio (analog technology) has nothing to do with transistors. Transistors only accelerate the miniaturization and integration of electronic systems and affect the micro-computing technology.

So it naturally affects the digital processing communication technology.

Therefore, tuning technology and amplitude modulation technology were born before vacuum tube triode, and the birth of vacuum tube laid the foundation for frequency modulation technology.

Amplitude and frequency modulation-still the dominant idea of modern communication theory, actually decades before the birth of transistors.