12 Technology And

It is important to understand the origin and the migration of EMC issues which have developed as a result of technological innovations during the last century. At the beginning of the 20th century, the technology of the day with regard to communications consisted primarily of generating high frequency radio signal by generation of high-voltage discharges.

The systems were used to send short messages and allowed experimentation with propagation characteristics and high-frequency transmissions. Since there were few of these systems, there were few instances of EMC.

In the late 1800's to the early 1900's, there was much work done with "wireless" (the original term for radio) communication. One person heavily involved in this work was Gugliemo Marconi. Marconi did many experiments in Italy and was interested in how to send messages across the airwaves. He studied the experiments that Hertz and other pioneers in the field were performing, and he wanted to conduct such experiments himself. His work involved sending RF energy across distances using some of the techniques shown in Figures 1.4 and 1.5. The key elements in his experiments were a method to create RF energy (which was accomplished by a high voltage coil), a power source (battery), and a way to transfer the energy to the air (plates). Today antennas accomplish this energy transfer. He then constructed a way to receive the energy by creating a receiver system that consisted of plates and a device that allowed the detection of the spark energy allowing the sound to be heard in headphones. A schematic diagram of his original system is shown in Figure 1.6. A schematic of one of his later developments is shown in Figure 1.7.

Figure 1.4. Marconi's 1895 Transmitter

Reproduced with the permission of Marconi Corporation plc from www.MarconiCaning.com

Figure 1.5. Marconi at Age 22 With His First Patented Wireless Receiver (1896)

Reproduced with the permission of Marconi Corporation plc from www.MarconiCalling.com

Figure 1.6. Schematic of Marconi's Original Wireless System

Reproduced with the permission of Marconi Corporation plc from www.MarconiCalling.com

Figure 1.7. Detailed Schematic of Marconi's 1900 Wireless System

Reproduced with the permission of Marconi Corporation plc from www.MarconiCalling.com

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