homework4f_solution

homework4f_solution - ECE 5325/6325 Fall 2009: Homework...

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Unformatted text preview: ECE 5325/6325 Fall 2009: Homework 4(f) Solution (4f) As shown in this figure, a WLAN signal arrives at a ground floor access point from a laptop (Pt=100 mW) on the 3rd floor, via scattering from a tree outside of the building. Neglecting wall/window losses, and assuming σRCS is 4 m2 and antenna gains of 3 dBi, what is the received power from the scatter path? Solution: The path lengths from the TX to the tree, and from the tree to the RS, are both √ d1 = d2 = 102 + 52 = 11.2 meters. An RCS of 4 m2 is equal to 6 dB meters2 . For WLAN, fc is about 2.4 GHz, so 20 log10 λ = −18.1. Note that the term is 20 log10 λ, not 20 log10 λ2 as it originally stated in my notes. Using the bistatic radar equation, Pr (dBm) = Pt (dBm) + Gt (dB) + Gr (dB) + σRCS (dB meters2 ) = 20(dBm) + 3 + 3 + 6 − 18.1 − 33.0 − 21.0 − 21.0 = −61.1(dBm) +20 log10 λ − 30 log 10 4π − 20 log 10 dt − 20 log10 dr ...
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This note was uploaded on 02/25/2011 for the course ECE 5325 taught by Professor Dr.nealpatwari during the Spring '10 term at University of Utah.

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