We generally think of wires when we talk about electricity. From Power Transmission lines to very thin conducting path in the printed circuit board we use wires for transferring energy from one end to other end. But we are never satisfied with the fundamental way of doing things, and therefore we tried to find out the way of transferring energy from one location to another location without the constraints of physical interconnections. There are various means of incorporating wireless functionality into an electrical system. The basis for RF communication electromagnetic radiation is one of these. But it’s important to note that electromagnetic radiation is not unique in its ability to extend electrical circuitry into the wireless arena. Anything which can travel through a non-conductive material— sound waves, heat , mechanical motion – could be used as a means of converting electrical energy into information that does not rely on conductive interconnections. Considering this, let us find out the answer to this relevant questions: Why is electromagnetic radiation the preferred method? Why are other types of wireless communication is treated as secondary importance?
Fields and Waves One can spend years studying the details of electromagnetism principles. Fortunately, we don’t need such type of expertise to design and implement a RF circuit successfully. Although, we need to have a basic idea of this mysterious energy being emitted from the device’s antenna. From the name itself it shows, electromagnetic radiation involves both electric and magnetic fields. If we have voltage – such as the voltage across the impedance of an antenna – we have an electric field. If we have electric current – such as the current passing through the impedance of an antenna – you have a magnetic field also. Even if the magnitude of the voltage or current is constant, the electric and magnetic fields are present. Unfortunately, these fields would not propagate, and to achieve this we need changes in voltage and current. The self-sustaining relationship between the electric and magnetic components of electromagnetic radiation is the key to this propagation phenomenon. An electrical field is generated by the changing magnetic field and vice versa. This mutual regeneration is evidenced as a distinct entity, namely, an electromagnetic wave. Once it gets generated, this wave will travel outward from its source, at the speed of light, toward the depths of the unknown.
Creating EMR and Controlling EMR It is not that easy to design a complete RF communication system, but it is very easy to generate electro-magnetic radiation (EMR). Even if we do not want to, we generate electro-magnetic radiation. Any circuit will generate EMR by any time-varying signal including digital signals. But this EMR is simply a noise in most of the instances. Of course, this can well be ignored if not causing any trouble. It becomes EMI (electromagnetic interference) when it interferes with other circuitry. Now we are certain that RF circuits design is not simply generating EMR but it’s a combination of art and science of generating, manipulating and interpreting EMR in such a way will allow one meaningful transfer of information between two circuits without having a direct electrical connectivity.