What Is Radio Frequency (RF)
Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around 20 kHz to around 300 GHz.
This is roughly between the upper limit of audio frequencies and the lower limit of infrared frequencies; these are the frequencies at which energy from an oscillating current can radiate off a conductor into space as radio waves. Different sources specify different upper and lower bounds for the frequency range.
Electric currents that oscillate at radio frequencies (RF currents) have unique properties that are not shared by direct current or super low frequency alternating current, which are used to distribute electricity.
Electric currents that oscillate at radio frequencies (RF currents)
- Electromagnetic waves will radiate energy from RF currents in conductors into space (radio waves). Radio technology is built on this foundation.
- The skin effect occurs when RF current does not penetrate deeply into electrical conductors and instead flows along their surfaces.
- Air can quickly be ionized by RF current, forming a conductive path through it. “High frequency” units used in electric arc welding, which use currents at higher frequencies than power distribution, take advantage of this property.
- Another property is the ability to appear to flow through insulating material, such as a capacitor’s dielectric insulator. This is due to the fact that capacitive reactance in a circuit decreases as frequency rises.
- A coil of wire, on the other hand, or even a single turn or bend in a wire may block RF current. This is because a circuit’s inductive reactance rises as the frequency rises.
Radio Frequency Electronics Circuits And Applications
The radio spectrum of frequencies is divided into bands with conventional names designated by the International Telecommunications Union (ITU):
FM Radio Trasmitter
The FM radio transmission transmitter, also known as an FM transmitter, is the most significant piece of radio transmitting equipment. The microphone picks up your voice, the audio processor improves it, and the mixer lets you monitor different aspects of the sound, but the radio transmitter is the most important piece of equipment since it is responsible for taking the sound from your studio and transmitting it to receivers in your listening area through an antenna.
An FM radio transmitter is made up of many components that work together to send data (in the case of radio broadcasting, sound is that information).
A typical FM radio broadcast transmitter that is used in FM broadcasting contains the following components:
- The transmitter is powered by an electrical signal from the power supply.
- The oscillator generates the carrier wave, or alternating current, that the transmitter sends via the antenna.
- The modulator modifies the carrier wave by adding information to it. The modulator in FM (tone modulation) either marginally raises or decreases the carrier wave’s frequency.
- The wave’s intensity is increased by the amplifier. A greater broadcast area is possible with more efficient amplifiers.
- The antenna converts the amplified signal to radio waves at the end.
FM Transmitter Circuit Example
#1. Simple FM Transmitter
#2. 7 Watt FM Transmitter
#3. 3 Watt FM Transmitter
#4. Stereo FM Transmitter
