Introduction

Wireless communication is the part of electronics that lets us carry information from one place to another without any physical wire joining the two ends — the message instead rides on radio waves that travel through free space. This chapter of the Karnataka 2nd PUC Electronics course builds that idea up step by step. It begins with what a communication system is and the blocks it is made of, looks at the noise that always tries to spoil a signal, and then studies how radio waves are produced and how they actually reach a distant receiver.

You will meet the three main paths a radio wave can follow — the ground wave, the space wave and the sky wave — and see why each one suits a particular band of frequencies. The middle of the chapter explains the ionosphere, the sun-charged layer high above the earth that bends short-wave signals back to the ground and so makes long-distance broadcasting possible. The closing section pulls these ideas together as sky-wave (ionospheric) propagation, including terms such as critical frequency, skip distance and fading that are regular favourites in the II PUC board exam.

Everything here is grounded in the state KTBS Electronics textbook, so a II PUC Electronics student can revise the whole ‘Wireless Communication’ unit from this reading without needing the printed book to fill a gap.