? Radio communication, broadcasting, television, radar, navigation, electronic countermeasures, remote sensing, radio astronomy and other engineering systems. Anyone who uses electromagnetic waves to transmit information works by antennas.
? In addition, when transmitting energy through electromagnetic waves, non-signal energy radiation also needs an antenna. Generally speaking, the antenna is reversible, that is, the same antenna can be used as both a transmitting antenna and a receiving antenna. The basic characteristic parameters of the same antenna for transmission or reception are the same. This is the reciprocity theorem of antenna.
1879, German engineer karl benz successfully tested the two-stroke experimental engine for the first time. 1June, 883, founded "Ben Ci Company and Rheinland Gas Engine Factory". 1in June, 885, he manufactured the first Ben Ci patented motor vehicle in Mannheim, which was a three-wheeled vehicle.
This car uses a two-stroke single-cylinder gasoline engine with 0.9 horsepower, which has some basic characteristics of modern cars, such as spark ignition, water cooling cycle, steel tube frame, leaf spring suspension, rear wheel drive, front wheel steering, brake handle and so on. 18861On October 29th, German engineer karl benz applied for a patent for his motor vehicle.
In June165438+1October of the same year, Karl Benz obtained the German patent (patent number: 37435a). This is considered to be the first modern car in the world. For the above reasons, people generally take 1886 as the first year of automobile, and some scholars take the year when Carl Benz made the first three-wheeled automobile (1885) as the year when the automobile was born.
Above content reference: Baidu Encyclopedia-Cars