The reason why the antenna can transmit information at high speed is that it can launch the electromagnetic wave carrying the information into the air, propagate at the speed of light, and finally reach the receiving antenna.
It is like transporting passengers with high-speed trains. If information is compared to passengers, then the tools for transporting passengers: high-speed trains are electromagnetic waves, and antennas are equivalent to stations, which are responsible for managing and dispatching the transmission of electromagnetic waves.
So, what are electromagnetic waves?
Scientists have studied the two mysterious forces of electricity and magnetism for hundreds of years. Finally, Maxwell of the United Kingdom proposed that an electric current can generate an electric field around it, a changing electric field generates a magnetic field, and a changing magnetic field generates an electric field. Eventually, this theory was confirmed by Hertz's experiments.
In such a periodic transformation of the electromagnetic field, electromagnetic waves are radiated and propagated into space.
An antenna is a "converter"—transforming a guided wave propagating on a transmission line into an electromagnetic wave propagating in free space, or vice versa.
What is a guided wave?
Simply put, a guided wave is an electromagnetic wave on a wire.
With an electric field, there is a magnetic field, with a magnetic field, there is an electric field, and so on, there are electromagnetic fields and electromagnetic waves.
The half-wave oscillator continuously propagates electromagnetic waves into space, but the distribution of signal strength in space is not uniform, like a ring like a tire.
But in fact, the coverage of our base station needs to be farther in the horizontal direction. After all, the people who need to make calls are all on the ground. Therefore, in the emission of electromagnetic wave energy, the horizontal direction needs to be enhanced and the vertical direction is weakened.
According to the principle of conservation of energy, the energy will neither increase nor decrease. If the emission energy in the horizontal direction is to be increased, the energy in the vertical direction must be weakened. Therefore, it is only necessary to flatten the energy radiation pattern of the standard half-wave array.
