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## [TowerTalk] Terrain question - takeoff angle

 To: [TowerTalk] Terrain question - takeoff angle ddjones@nas.com (Dale Jones K5MM) Sun, 19 Jul 1998 06:33:11 -0700 (PDT)
 ``` Mike, One-and-one-half miles is about 7500 feet. Use trigonometry and you will see that you have a triangle that is 7500 feet as the horizontal distance to the base of the hill, and the hill is then 1100 feet high. Then: The tangent of Some Angle = 1100 / 7500 = 0.1467, Then the ArcTangeant of "0.1467" states that the angle is 8.35 Degrees. This states that your take-off angle from ground level at your house is about 8.5 degrees. If you are using high-gain 2 meter antennas for SSB scatter, that angle will be a BIG hindrance to you. If you are using 3 element yagis for HF, not much of a problem. In general that 8 degree angle to the top of the hill is NOT good news, but then it's not especially bad for HF either. It would show up as being bad when you wanted to work Long Path in that direction, where you are looking for antenna take-off angles of 2 to 4 degrees. You can use the same technique above to determine the take-off angle to the larger mountains east and north-east of you. Depends on how far away they are. 73 & GL Dale K5MM +++++++++++++++++++++++++++++++++++++++++++++++++++++++ At 07:45 AM 7/19/98 +0100, you wrote: > >Here is a good one for the masses. >I have to the north of me about 1.5 miles a hill of about 1100 feet how is >this going to effect radiation angle? >We wont mention the 5000 foot mountains to the northeast and east of me as >they are much farther away. >Mike...NO6X -- FAQ on WWW: http://www.contesting.com/towertalkfaq.html Submissions: towertalk@contesting.com Administrative requests: towertalk-REQUEST@contesting.com Problems: owner-towertalk@contesting.com Search: http://www.contesting.com/km9p/search.htm ```
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