13.07.2015 Views

View File - University of Engineering and Technology, Taxila

View File - University of Engineering and Technology, Taxila

View File - University of Engineering and Technology, Taxila

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

<strong>and</strong> the azimuth angle is a z ¼ 180 þ tan 1 tan Dsin L ETAlternatively,degð2:22aÞsin Da z ¼ 180 þ pffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffideg ð2:22bÞ1 cos 2 L ET cos 2 DFor the Southern Hemisphere azimuth angle, the 180-term is deleted. Themagnetic heading <strong>of</strong> the antenna can be expressed asa H ¼ a z þ D a deg ð2:23Þwhere D a is the deviation, as the angle between true North Pole <strong>and</strong> the Northmagnetic Pole.Example 2.1: An earth station antenna is located at 90 W longitude <strong>and</strong> 35 Nlatitude. It is intended to transmit <strong>and</strong> receive signals to a satellite ingeostationary orbit at 82 W longitude. Assume a deviation angle <strong>of</strong> 3:3 .Calculate the compass heading the antenna would be pointing to <strong>and</strong> itselevation.SolutionD ¼ 82 89 ¼ 7 L ET ¼ 35 From (2.20a), the elevation angle!y ¼ tan 1 cosð 7Þ cosð35Þ 0:1512pffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi¼ 48:67 1 cos 2 ð 7Þ cos 2 ð35ÞUsing (2.21), the true elevation is calculated as 48:68 : The azimuth angle iscalculated using (2.21b):sin Da z ¼ 180 þ pffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi¼ 168 1 cos 2 L ET cos 2 DConsequently, the compass heading is estimated using (2.23):a H ¼ a z þ D a ¼ 164:7 Copyright © 2002 by Marcel Dekker, Inc. All Rights Reserved.

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!