In cellular communication systems, there is a two-way wireless transmission between the cellular phone handset and the base station tower. The cell phone converts the audio signals into electrical form using a microphone. This information is imposed on a high frequency carrier signal by the process of modulation. The modulated carrier is radiated into free space as an electromagnetic wave which is picked up by the base station tower. In the same way, the signals transmitted by the base station tower are received by the cellular phone handset, hence establishing a two way communication.
Cellular communication system is therefore a wireless communication structure which uses free space as a medium to transfer information from the transmitter to the receiver. An important component of a wireless link is the antenna which efficiently couples electromagnetic energy from the transmitter to free space and from free space to the receiver. An antenna is normally a bidirectional device, that is, the power through the antenna can flow in both the directions, and therefore it works as a transmitting as well as a receiving antenna.
Related: Radio Frequency Spectrum Analyser
Transmissions lines are used to transfer electromagnetic energy from one point to another within a circuit and this mode of energy transfer is typically termed to as guided wave propagation. An antenna acts as an interface between the radiated electromagnetic waves and the guided waves.
Also read: Basics of Radio Frequency (RF) and Wireless Communication Systems
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