Frequency, Resonance and Radio Waves

Radio is a very important instrument in our daily life. Most people do not know how to keep the radio functioning. On the radio, many parts are required to maintain the operating frequency of the radio, and both resonance and radio waves are all parts necessary to supply power to the radio. Frequency represents the number of occurrences of repeat events per unit of time. Frequency transmits acoustic signals with sound waves. FM also represents frequency modulation. FM and AM are key leaders in the transmission of music and text.

Modulation is the process of pressing one wave system to another higher frequency. Audio (AF) waves such as voice and music from tapes and microphones need to be combined with radio frequency (RF) carriers for wireless transmission. The frequency (oscillation speed) or amplitude (height) of the carrier wave can be changed by a process called modulation. The AF wave enters the modulator and interacts with the carrier to determine the amplitude of the carrier (amplitude modulation - AM) or carrier frequency (frequency modulation - FM). Afterwards, the modulated carrier is sent to its destination. When received, the modulated carrier wave is fed to a decoder or demodulator from which the original AF waves are extracted.

Carrier waves are radio frequency waves carrying information. This information is added to the carrier by a modulation process that includes a change in one of the carrier frequency characteristics such as amplitude, frequency or duration. In the amplitude modulation, the information signal changes the amplitude of the carrier wave, and a frequency band called a sideband occurs on both sides of the carrier frequency. These sidebands (each pair of modulation frequencies) cover a frequency range equal to the sum and difference of the carrier frequency and the information signal.

In AM transmission, the amplitude of the carrier wave varies with the change of the electromagnetic wave from the radio studio. In FM transmission, the amplitude of the carrier wave does not change. However, the wave frequency changes according to the electromagnetic wave transmitted from the studio. AM transmitter broadcasts two types of radio waves. The ground wave spreads horizontally from the ground and propagates along the ground surface. On the other hand, radio waves propagating upward toward the ionosphere transmit the AM transmission over long distances. AM radio stations with powerful transmitters can reach reaching audiences up to 1000 miles (1600 km) away.