What is Radio Frequency (RF)?

In this part, we are going to talk about radio frequency radio frequency, your RF is any electromagnetic wave frequencies that lie in the ranges starting from around three kilohertz to 300 gigahertz, as you see it starting from intermediate frequency and ends in really high frequency. What is the purpose of using RF filled? We say RF field can be used for various types of wireless broadcasting and communications, so we use transmitters and receivers and also antennas in order to send and receive data and communicate. What are the applications? We can see there are lots of applications for radio frequency, cell phones, radio, television, Wi-Fi. Even if we go more advanced, we can have satellite communications. This picture shows the RF system in a very simple way, so imagine that we have two devices, one and two. So they are trying to communicate and talk with each other. So they are sending and receiving these waves and they have their data inside these waves. So as you see, these electromagnetic waves have the radio frequency. So there are two cases in the system that we have to study. First, we can say, for example, this device can only send data and this the second one can only receive it. So this one is sending and it's one direction. So and this one is received. So we can say this is a transmitter. So this is t we call it and this is receiver. So this is our X. And it can be also a different case, for example, these two systems can be Teagues and are at the same time, it means that this device can send electromagnetic waves to the second one and also receive from second one. So this time this is these are X and we are going to talk about this in upcoming lectures. There are two points we have to be careful in our system. First one is these systems are trying to communicate with the waves that have RF frequency. So we say we have radio frequency here, RF. And second one is these two systems are not connected to each other physically. There are no connection between them physically with a wire, for example. So we say the system is wireless. The RF spectrum is divided into several range or bands, with the exception of low frequency segment. Each band represent an increase of frequency corresponding to an order of magnitude. So we are going to explain the RF spectrum in the following table. And as you see in this picture, we can see we can divide the RF frequency range into different groups. So we start with very low frequencies from nine kilohertz to 30 kilohertz. And it goes to low frequency and then it goes on and we reached extremely high frequency here is from 30 gigahertz to 300 gigahertz. So we call this a spectrum. As you see, the range is divided into different categories. And we most of the time allocate this range to different kind of applications we are going to show in the next slide. And what about the wavelengths? We have to explain the wavelength here because we are going to use it. We say the wavelengths is equal to the speed of light over the frequency of oscillation. So wavelength is Lunda here we show it with Lunda is proportional to inverse of frequency. It means that if we increase our frequency, we are reducing the wavelength links. So as you see here, the wavelengths for low frequency range is really high, starting from 10 to 333 km. But when we are increasing our frequency, we have a very low wavelength. As you see here is a millimetre. That's that's why we call this millimeter wave. At this point, we are going to explain the wavelengths. Imagine that there is a war and you are trying to tap in the middle of the square, so you are producing VAW. So what is the wavelength here? As you see, if you see the cross section of the water is like this, so the wavelength is the links between the two peaks of the wave. So, for example, wavelength is here. This is the lambda here we can show with lambda. This is the links between two peaks of the wave and the relationship between wavelength and frequency is shown in this picture, as you see for the first wave. We have the frequency of F one for the second, we have the frequency of F2 and we say if one is higher than if two. But as you see, this one has the short wavelength, so we see one is lower than London two. So this shows the relationship between the wavelength and frequency.