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echo: ham_tech
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from: ROB DENNIS
date: 1997-12-22 20:24:00
subject: LPA Antennas Part 4

 Original article from: Wayne Sarosi 
 Reposted by Rob Dennis,Moderator HAM_TECH,for use of the FIDO HAM_TECH echo.
  THIS POST/SERIES NOT TO BE USED IN ANY CDROM COMPILATIONS FOR COMMERCIAL
 SALE WITHOUT EXPRESS WRITTEN PERMISSION OF ORIGINAL AUTHOR(S) OF THIS POST.
               ALL AND ANY COPYRIGHTS RETAINED BY AUTHOR(S).
LPA Series - 141-149 MHz (2m + MARS/CAP)
USE:  Amateur Band 2m and MARS/CAP Frequencies
Note: See ARRL Antenna Handbook under LPA construction
Tau = 0.965
Sigma = 0.181
B = 1.0567
COT alpha = 20.686
BAR = 1.295
Bs = 1.368
Lambda max = 6.9787-ft
Lb = [0.25(1-(1/Bs))COT alpha)Lambda max] = 9.71-ft
N = 1 + (log Bs / log (1/Tau)) = 10
The following are in inches,two of each required (L)
-+----------------------------
 L1 = 21.84               d1,2 = 15.163
 L2 = 21.10               d2,3 = 14.632
 L3 = 20.40               d3,4 = 14.120
 L4 = 19.71               d4,5 = 13.626
 L5 = 19.06               d5,6 = 13.149
 L6 = 18.42               d6,7 = 12.689
 L7 = 17.81               d7,8 = 12.245
 L8 = 17.22               d8,9 = 11.816
 L9 = 16.65              d9,10 = 11.402
L10 = 16.09
Zt =10.468  Sigma' = Sigma/sqrt Tau = 0.18425
Ro = 50
Zav = 265.66
Zo = Ro^2/(8(Sigma'(Zav))) + Ro(Sqrt(Ro/(8(Sigma'(Zav))) + 1) = 57.0428
Gain = 10.5 dBi
S can be calculated from the ARRL Antenna Handbook, but is 0.804 for
0.25-in elements and 1-in booms.
 Next is the 6m LPA.  Element attachment will be after the 6m posting.
 SEE BELOW!!!!
*************************************************************
*    NOTE: The boom on all these LPAs is 1-inch diameter.   *
*    All elements have a 0.9-in adjustment in the length    *
*    to compensate.  Sorry about that.  The Freq file will  *
*    have the proper statement put in.                      *
*************************************************************
-WS
--- GoldED 2.42.G1219
---------------
* Origin: VE3SJN....Moderator....HAM_TECH (1:163/506.4)

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