Wireless Communication Introduction to the Amplifier

Question: Describe about the Wireless Communication for Introduction to the Amplifier. Answer: 1: Amplifier Amplifier is a device which can increase the power of the input signal and provides the output signal with more strength. Amplifiers are generally used in wireless communications and in audio equipment to increase the voltage, power or current of the input signal to enhance the quality of the audio received or transmitted by the audio equipment. There are different types of amplifiers depending on the configuration of their circuits and the method of amplification. Type of Signal Type of Configuration Classification Frequency of Operation Small Signal Common Emitter Class A Amplifier Direct Current (DC) Large Signal Common Base Class B Amplifier Audio Frequencies (AF) Common Collector Class AB Amplifier Radio Frequencies (RF) Class C Amplifier VHF, UHF and SHF Frequencies The figure below shows an ideal amplifier model which defines various terms like input signal, output signal and gain in the process of amplification. The gain of an amplifier is known as the difference between the input signal and the output signal, which in turn defines the amplification capability of the amplifier (Kazimierczuk, 2014). Figure 1 Ideal amplifier model (source: https://www.electronics-tutorials.ws) The amplifiers used in radios are capable for amplifying high-frequency signals used for radio communications and are known as RF amplifiers. These amplifiers in the radio amplify the signals broadcasted from the radio stations. This amplification of the broadcasted signal allows the reduction of noise and tuning of the signal to a specific frequency. This allows the turned RF amplifiers in the radios to tune to a specific frequency, which in turn allows the users to listen to specific radio channels without being distorted by the other radio frequencies i.e. the other radio channels being broadcasted. So the amplifier in a radio allows the user to tune to specific frequency by amplifying the low-power radio frequency to high-power radio frequency (Figure 1, 2013). 2. Mixer Mixer is an electronic device which takes two input signals and mixes them to create an output signal with higher bandwidth, power or voltage. The usage of the frequency mixers is very high in terms of the wireless or radio communications, as it is one of the most efficient way to shift an input signal from one frequency range to another. Such a shift of the input signal to a different frequency range allows efficient further processing of the signal or broadcasting of the signal. One of the usage of the mixers in the radio communications is as a modulator for the transmission of the radio signal. The modulation process allows the radio signal to be mixed with a carrier frequency higher or lower than it for the effective transmission from the radio stations. This is called a sideband frequency i.e. the band of frequencies either higher or lower than the carrier frequency responsible for the transmission of signal and the mixers are used as the modulators to achieve the final mix of t he sideband and carrier signal. There are different types of modulation process which results in different combination of the output signals as the result of the process (Jones, 2014). The amplitude modulation process results in a final signal having two different sidebands i.e. the sideband having frequencies lower than the carrier frequency, lower sideband (LSB) and the sideband having frequencies higher than the carrier frequency, higher sideband (HSB). Figure 2 Modulation process (source: https://www.tpub.com) The mixers are utilized in this modulation process to create the final signal to be transmitted or broadcasted. So the effective transmission of data over the carrier frequency is supported by the modulation with sideband frequencies either lower or higher than the carrier frequency. The modulation process in turn results in higher power of the output signal, which results in better quality transmission and broadcasting (Figure 3, 2016). 3 Multiplexing techniques CDMA and FDMA The technique of multiplexing is to combine a number of data streams and sources together to transmit them simultaneously over a common medium. The technique of demultiplexing is used in the receiver side to separate each of these data streams or sources from each other in the received signal. These techniques are utilized heavily in the wireless communication in order to share the transmission media among a wide range of data to be transmitted or broadcasted. There are different types of multiplexing techniques based on the implementation of the core process. The concept or technology of wireless networking is based on these multiplexing technologies, which provide users with specific access methods to access the shared bandwidth. Two of the most common access methods are Code Division Multiple Access (CDMA) and Frequency Division Multiple Access (FDMA). FDMA allows the entire bandwidth of the shared network to be divided into separate frequency bands (Ghanim, 2013). Each of these b ands are used for the access of each of the users of the system to the shared wireless network. But in case of CDMA, the input analog signal is converted into the digital version before being split into small divisions over a wide spectrum of bandwidth. Each of the division of the input signal is assigned with a code for the tracking and operational purposes. CDMA is generally used in the telecom industry to handle the calls over a wide spectrum of frequencies (Figure 3, 2016). Figure 3 Types of access methods (source: https://www.itu.int) References Figure 1 Introduction to the Amplifier: An Amplifier Tutorial. (2013). Basic Electronics Tutorials. Retrieved 20 August 2016, from https://www.electronics-tutorials.ws/amplifier/amp_1.html Figure 2 AM transmitter principles. (2016). Tpub.com. Retrieved 20 August 2016, from https://www.tpub.com/neets/book12/48k.htm Figure 3 All about the Technology. (2016). Itu.int. Retrieved 20 August 2016, from https://www.itu.int/osg/spu/ni/3G/technology/ Balanis, C. A. (2016). Antenna theory: analysis and design. John Wiley Sons. Ghanim, M. F., Abdullah, M. F. L. (2013). Wireless broadband access technologies. LAP LAMBERT Academic Publishing. Jones, T. L., Davis, R. D., Imbornone, J., Wang, X. (2014). U.S. Patent No. 8,624,658. Washington, DC: U.S. Patent and Trademark Office. Kazimierczuk, M. K. (2014). RF power amplifier. John Wiley Sons. Pynttari, V., Halonen, E., Sillanpaa, H., Mantysalo, M., Makinen, R. (2012). RF design for inkjet technology: Antenna geometries and layer thickness optimization. IEEE Antennas and Wireless Propagation Letters, 11, 188-191. Schmid, R. (2015). Antenna Working Group Technical Report 2015. IGS Technical Report, 2014, 129-132. Stutzman, W. L., Thiele, G. A. (2012). Antenna theory and design. John Wiley Sons.