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## [TowerTalk] stacking antennas & Rohn specs

 To: [TowerTalk] stacking antennas & Rohn specs k1my@nlis.net (Bruce Makas) Wed, 09 Jul 1997 08:04:43 -0400
 ```I am installing several Rohn towers and want to stack antennas on the towers. Being a "good" amateur engineer, I intend to follow the specs in the Rohn catalog. My question is about the allowable projected area that is called out by Rohn. For example, if I were to put up 130 foot of Rohn 45G in a 90 mph area (coastal Maine), the book says that 12.3 sq ft of projected area of round elements is allowable (C870478R1). I assume that is at the top of the 130 foot tower. Now, I want to stack antennas; say one at 60 feet, one at 100 feet and one at 130 feet. How do I calculate what is the allowable sq footage? Is it as simple as summing the moment arms (height x sq ft of each antenna compared against 130 ft x 12.3 sq ft) or is it more complicated? For example, a 205CA specs out at 9 sq ft, I would hope that I could put at least three of these, and 3 155CA's (5.2 feet each) on the tower, but it doesn't look it. ((60x9)+(100x9)+(130x9)) > (130x12.3) ........... for just the 205CA's If this is true, how can anyone stack more than 3 large antenna's per tower? Even a 55G installation only allows 14.8 sq ft @ 130 feet. What am I doing wrong? Thanks in advance for your ongoing support of my antenna project. 73, Bruce ffff,0000,0000 \\\|/// ( 0000,0000,ffffO O ffff,0000,0000) _________________________( )_____o0O__________________ | | ffff,0000,0000| 0000,0000,ffffBruce Makas, K1MY ex: K1MTY, W9NSM, W4PAK, ffff,0000,0000| 0000,0000,ffff ffff,0000,0000|0000,0000,ffff 58 Stonegate Road N9AFY, KB9US, KS9Z ffff,0000,0000| 0000,0000,ffff ffff,0000,0000|0000,0000,ffff Cape Elizabeth, Maine E-mail: k1my@nlis.net ffff,0000,0000| ffff,0000,0000| 04107 USA Phone: 207 / 767-8150 ffff,0000,0000| |________________OOo___________________________________| |__| |__| || || 0000,0000,ffff (__) (__) -- 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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