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Note for Circuit Analysis - CA By Buddies Sairamit

  • Circuit Analysis - CA
  • Note
  • Sri Sai Ram Engineering College - SEC
  • Electronics and Communication Engineering
  • 4 Topics
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www.padeepz.net UNIT I BASIC CIRCUITS ANALYSIS AND NETWORK TOPOLOGY FUNDAMENTALS OF COMMUNICATION ENGINEERING Networks: .n et Symmetrical and asymmetrical networks. characteristic impedance and propagation constant Derivation of characteristic impedance for T and Pi networks using Zoc and Zsc, image and iterative impedances - Derivation of Zi1 and Z i2 for asymmetrical T and L networks using Zoc and Zsc, Derivation of iterative impedances for asymmetrical T network. Equaliser: types, applications: constant resistance equalizer. ( No derivations) ad ee pz Symmetrical Networks: w w Antenna: w .p A network in which all devices can send and receive data at the same rates. Symmetric networks support more bandwidth in one direction as compared to the other, and symmetric DSL offers clients the same bandwidth for both downloads and uploads. A lesser used definition for symmetric network involves resource access—in particular, the equal sharing of resource access. Basic antenna principle, directive gain, directivity, radiation pattern, broad-side and end -fire array, Yagi antenna, Parabolic antenna. Antenna Directivity: Directivity is an important quality of an antenna. It describes how well an antenna concentrates, or bunches, radio waves in a given direction. A dipole transmits or receives most of its energy at right angles to the lengths of metal, while little energy is transferred along them. www.padeepz.net

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www.padeepz.net If the dipole is mounted vertically, as is common, it will radiate waves away from the center of the antenna in all directions. However, for a commercial radio or television station, a transmitting antenna is often designed to concentrate the radiated energy in certain directions and suppress it in others. For instance, several dipoles can be used together if placed close to one another. Such an arrangement is called a multiple-element antenna, which is also known as an array. Antenna: ad ee pz Basic Antenna principle: .n et By properly arranging the separate elements and by properly feeding signals to the elements, the broadcast waves can be more efficiently concentrated toward an intended audience, without, for example, wasting broadcast signals over uninhabited areas. w w w .p Antenna, also referred to as an aerial, device used to radiate and receive radio waves through the air or through space. Antennas are used to send radio waves to distant sites and to receive radio waves from distant sources. Many wireless communications devices, such as radios, broadcast television sets, radar, and cellular radio telephones, use antennas. Receiving antennas come in many different shapes, depending on the frequency and wavelength of the intended signal. How Antenna works? www.padeepz.net

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www.padeepz.net A transmitting antenna takes waves that are generated by electrical signals inside a device such as a radio and converts them to waves that travel in an open space. The waves that are generated by the electrical signals inside radios and other devices are known as guided waves, since they travel through transmission lines such as wires or cables. .n et The waves that travel in an open space are usually referred to as free-space waves, since they travel through the air or outer space without the need for a transmission line. A receiving antenna takes free-space waves and converts them to guided waves. ad ee pz Radio waves are a type of electromagnetic radiation, a form of rapidly changing, or oscillating, energy. Radio waves have two related properties known as frequency and wavelength. w .p Frequency refers to the number of times per second that a wave oscillates, or varies in strength. w w The wavelength is equal to the speed of a wave (the speed of light, or 300 million m/sec) divided by the frequency. Low-frequency radio waves have long wavelengths (measured in hundreds of meters), whereas high-frequency radio waves have short wavelengths (measured in centimeters). An antenna can radiate radio waves into free space from a transmitter, or it can receive radio waves and guide them to a receiver, where they are reconstructed into the original message. For example, in sending an AM radio transmission, the radio first generates a carrier wave of energy at a particular frequency. The carrier wave is modified to carry a message, such as music or a person's voice. The modified radio waves then travel along a transmission line within the radio, such as a wire or cable, to the antenna. The transmission line is often www.padeepz.net

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www.padeepz.net known as a feed element. When the waves reach the antenna, they oscillate along the length of the antenna and back. Each oscillation pushes electromagnetic energy from the antenna, emitting the energy through free space as radio waves. The antenna on a radio receiver behaves in much the same way. As radio waves traveling through free space reach the receiver's antenna, they set up, or induce, a weak electric current within the antenna. The current pushes the oscillating energy of the radio waves along the antenna, which is connected to the radio receiver by a transmission line. The radio receiver amplifies the radio waves and sends them to a loudspeaker, reproducing the original message. .n et Yagi antenna: w w w .p ad ee pz The Yagi antenna or more correctly, the Yagi - Uda antenna was developed by Japanese scientists in the 1930's. It consists of a half wave dipole (sometimes a folded one, sometimes not), a rear "reflector" and may or may not have one or more forward "directors". These are collectively referred to as the "elements". The Yagi antenna consists of 2 parts: the antenna elements the antenna boom www.padeepz.net

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