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echo: ham_tech
to: JEFF EDMONSON
from: ROY WITT
date: 1997-09-02 12:51:00
subject: Wayne Sarosi

Hello Jeff.
30 Aug 97 11:22, Jeff Edmonson wrote to All:
 JE> Got e-mail from Wayne last night (thanks, Rob! :-> )
 JE>
 JE> I've asked him for some of the text files that he had collected on
 JE> antennas and various other subjects so I could upload them here, for
 JE> all - for Technical discussion.
I've got some of those if you want...
 From : Wayne Sarosi  1:374/73.2  08 Feb 97  20:30:03  Subj : LPDA-1
I found some old posting I made on the LPDA-HF.
There are three in the series. Here they are:
06 June 1991
FROM: Wayne M. Sarosi
      AFA2GN, PAFB MARS Team, Patrick Air Force Base, FL
To:   All MARS operators.
SUBJECT: Log Periodic Dipole Array (LPDA) Design
DISCUSSION:
This antenna was designed to operate from 13.8 MHz to 28.8 MHz. The antenna
was to cover the majority of the USAF MARS frequencies yet give the operator
a smaller log periodic than the commercial types, that had reasonable gain,
and was cost effective to build. All design formulas are taken from the
ARRL Antenna Manual.
The antenna did not turn out as planned. The frequency range actually went
from 13.5 MHz to 29.5 MHz with SWR less than 1.8:1. Most SWR readings were
less than 1.5:1 across the band. The weight was a surprize also. I expected
100 pounds plus, but actually was under 63 pounds.
SPECIFICATIONS:
     Boom: 22-ft, 3-in diameter, aluminum.
     Number of Elements: 10
     Feed: Balanced
     BALUN: 4:1
     Weight: 62-lb
     Windload: near 9 sq.ft.
     Cost: About $200.00  Note: $150 for element insulators from HY-Gain.
                                $50 for misc. Tubing, boom, etc from
                                 old antennas discarded by fellow hams,
                                 CBers, and field day.
     Time: 80-hrs, including install.
     Design Bandwidth: 13.8 MHz to 28.8 MHz
     Actual Bandwidth: 13.5 MHz to 29.5 MHz*, Highest my TS-430S would go.
     SWR MAX: 2.1:1
     SWR AVE: 1.4:1
     SWR LOW: 1.1:1, all taken on an MFJ-986 Differential-T Tuner/SWR/PWR
                     meter.
     EST GAIN: 6dB
     PWR Handling: Max Legal.
     Turning radius: same as 20m, 3 element Yagi
     Height off the ground: 35-ft minimum for best results
                            (half wave at 14 MHz).
                                                              1.
     ELEMENTS: (Half element lengths given and quantity)
               Note: Elements start at rear, longest first.
          L10: (492/13.8)/2 = 17.826-ft, quantity (2)
          L09: L10 * 0.9 =    16.043-ft, quantity (2)
          L08: L09 * 0.9 =    14.439-ft, quantity (2)
          L07: L08 * 0.9 =    12.995-ft, quantity (2)
          L06: L07 * 0.9 =    11.696-ft, quantity (2)
          L05: L06 * 0.9 =    10.526-ft, quantity (2)
          L04: L05 * 0.9 =     9.473-ft, qauntity (2)
          L03: L04 * 0.9 =     8.526-ft, quantity (2)
          L02: L03 * 0.9 =     7.673-ft, quantity (2)
          L01: L02 * 0.9 =     6.906-ft, quantity (2)
     ELEMENT SPACING: d(L10-L09) = 2*(.5(L10 - L09) cot(0.5 * apex angle))
                      The cot(0.5 * apex angle) = 2.
                      Thus: d(L10-L09) = (L10 - L09)*2
                      AND: d(L09-L08) = d(L10-L09) * 0.9
          d(L10-L09) = 3.566-ft
          d(L09-L08) = 3.209-ft
          d(L08-L07) = 2.888-ft
          d(L07-L06) = 2.599-ft
          d(L06-L05) = 2.339-ft
          d(L05-L04) = 2.105-ft
          d(L04-L03) = 1.895-ft
          d(L03-L02) = 1.706-ft
          d(L02-L01) = 1.535-ft
          0.5 * Apex angle: 26.565
          cot(0.5 * apex angle): 2
Further detail is given in the ARRL Antenna Book under Log Periodic
Dipole Array.
     Mounting: 1/4-in aluminum plate 10-in X 10-in
               (4) U-bolts to fit 3-in boom & mast
               1/2-in stainless steel bolt, spacers, lockwashers and nuts.
               ---------------------------------
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               ---------------------------------
Bolt through center allows for pivoting of mast for element placement
or repair. Bolt configuration: Nut-L.  Washer, Washer, Boom, Washer,
Nut, Washer, Plate, Nut. Any questions, please feel free to contact
me at the following address:
                    Wayne Sarosi
                    995 Alabama Street
                    Titusville, FL 32796
                                                              2. ... A true 
diplomat struts sitting down.
---------------
* Origin: KB6PI's Antenna Farm * San Diego, CA (1:202/909.10)

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