Wednesday, September 25, 2019

Microwave and Photonics Systems Essay Example | Topics and Well Written Essays - 2000 words

Microwave and Photonics Systems - Essay Example This results in significantly reduced complexity of the Remote Antenna Unit, as the major portion of the processing is avoided, at least at the regional unit level and only optoelectronic conversion and amplification of the converted signal is necessary. 2) Estimate a difference in roundtrip time for data transmission between Tokyo and San Francisco (distance: 8270 km) as for the following two communication methods; radio-wave (wireless) communication using a geostationary satellite, and fiber-optic communication. Assume that a refractive index for the air is 1, and that of the optical fiber is 1.5. Distance between the earth and the satellite is 38,800 km. Impedance matching in a circuit comprised of linear devices is defined as the process of making the output impedance of the source equal to the input impedance of the load, in order to maximize the power transfer from source to load and thereby minimize reflections from the load end. This results in increased efficiency. In the context of radio and fiber optics systems, where the wavelength of the transmitted signal is very much less in comparison to the length of the line, ie, where the changes in the signal are rapid compared to the time of propagation, the impedances at each end of the line must be matched to the characteristic impedance of the transmission line to prevent reflections of the signal at the ends of the line. Otherwise, echoes may occur and cause the formation of standing waves in the transmission line. In radio-frequency (RF) systems, a common type of RF load used is a quarter-wave ground plane antenna using a modified ground plane or a matching network. 4) Explain one example of representative antennas which are used in our radio wave(wireless) systems such as cellular phones, wireless LANs, etc, with respect to its type and operation. Ans) Consider a microstrip antenna as an example. A microstrip antenna gains its name from the fact that it is structurally a simple metallic strip of desired shape suspended over a ground plane. The strip may be flush mounted onto a dielectric or other surface. The feed line is placed behind the ground plane (Prasad 809). They are simple to fabricate and easy to modify and customize. The microstrip patch antenna is the most common type of microstrip antenna. It is a narrowband, wide-beam antenna with an inherent ability to have polarization diversity. These antennas can easily be designed to have Vertical, Horizontal, Right Hand Circular or Left Hand

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