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 holl_ands | Home > Log-Yagi & Dual-Driven Antennas  
Log-Yagi & Dual-Driven Antennas
Log-Yagi and Dual-Driven Antennas analyzed using 4nec2:

a) FM Band, Antennacraft FM-6, 6-Element Log-Yagi.

b) Wade-Delhi C-101-5 10-element Ch3-5 Log-Yagi, 148-inch Boom.

c) Winegard YA-1713, 10-element Hi-VHF Log-Yagi, 98-inch Boom.

d) Antennacraft Y10-7-13, 10-element Hi-VHF Dual-Driven Yagi, 120-inch Boom.

e) Antennacraft Y10-2-6, 10-element Ch2-6 [+ 7-13] Log-Yagi, 147-inch Boom.
Date(s): 25Jan2011. 1 - 8 of 8 Total. Shared
Ch2-13 Delhi 5-El Dual-Driven FD Yagi
1. Ch2-13 Delhi 5-El Dual-Driven FD Yagi  (16 Aug 2012)
Ch2-13 Delhi 5-Element Dual-Driven Folded Dipole Yagi analyzed using 4nec2. Rear Fed was slightly better than Front Fed.
Dimensions per octopod's posted measurements:
Boom Length=57.5-in.
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20 Images
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Lo-VHF A-C Y-10-2-6 Log-Yagi
2. Lo-VHF A-C Y-10-2-6 Log-Yagi  (25 Apr 2018)
Antennacraft Y-10-2-6, 10-Element, Lo-VHF Log-Yagi analyzed using 4nec2.
Boom Length = 147-in.  4nec2 file by holl_ands based on measurements by Sev.

Ch2-6 Gain = 6.6 to 10.2 dBi, F/B & F/R  typically 15 dB and SWR (300-ohms) is a bit high
and excessive on Ch2.  [See below EVAL Performance Summary *.txt File.]

There is usable Gain in lower FM Band which drops off in upper FM Band.

Ch7-15 Raw Gain = 6.2 to 3.3 dBi is minimal, F/B & F/R Ratio about 8-9 dB and SWR (300-ohms) under 1.7.
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UHF Lindsay I6LPU66 Log-Yagi
3. UHF Lindsay I6LPU66 Log-Yagi  (20 Oct 2017)
UHF Lindsay I6LPU66 Log-Yagi Antenna with 14 LPDA Element Pairs and 7 Yagi type Directors.
So far just photos....need to clarify a few details before preparing a 4NEC2 Model...

NOTE: Keep clicking on images [3 times] until you see the original 4 MB Hi-Rez Image.
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21 Images
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FM-6 Antennacraft 6-Element Log-Yagi
4. FM-6 Antennacraft 6-Element Log-Yagi  (13 Aug 2013)
FM Band, Antennacraft FM-6, 6-Element Log-Yagi analyzed using 4nec2, after converting K6STI's FM-6 file in Yagi-Optimizer (YO) File format.
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12 Images
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Ch3-5 Wade-Delhi C-101-5 Log-Yagi
5. Ch3-5 Wade-Delhi C-101-5 Log-Yagi  (16 Dec 2012)
Ch3-5 Wade-Delhi C-101-5 10-Element Log-Yagi with 148-inch Boom analyzed using 4nec2.
(Uses two Tri-poles interconnected by a Crossover Feedline).

About 9-11 dBi Gain and SWR under 2.5 across Ch3-5.
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12 Images
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Hi-VHF Winegard YA-1713 Log-Yagi
6. Hi-VHF Winegard YA-1713 Log-Yagi  (December 30, 2008)
Hi-VHF Band, 10-Element, Winegard YA-1713 Log-Yagi Antenna is investigated, using 4nec2 Antenna Simulation Software.

Ken Nist's EZNEC antenna simulation results for numerous antennas are summarized here: www.hdtvprimer.com/ANTENNAS/comparing.html.
In the VHF charts, the YA-1713 had severe loss across channel 13.  However, this is NOT what is found in the ants.xls charts
(which only summarized center channel gain), see www.hdtvprimer.com/SIMS.  Further investigation of the posted w1713a.ez NEC file
reveals it assumed DIFFERENT element sizes and other measurements than a recently purchased YA-1713.  [Did W-G change it????]
Surprisingly, Ken Nist found 300-ohm impedance, vice 75-ohm for newer YA-1713 (holl_ands below) with different dimensions.

4NEC2 simulation results are presented for both antenna measurements, demonstrating which assumptions can be ignored and
which lead to severe loss across channel 13.

UPDATE (29Jan2009): Prelim On-Air Test (at 10-ft height) was conducted 70 miles SE from Mt Wilson, inserting an RF attenuator
to find audio & video degradation levels.  If there truly is gain loss across Ch13, NTSC audio carrier should be more susceptible to loss.
However, NO DIFFERENCE was observed wrt either audio or video performance on Analog Ch13 compared to Analog Ch7, 9 and 11,
nor was there any noticeable difference between audio & video degradation levels on Ch13.

Hence the Ch13 gain loss found in overly simplified NEC simulations appears to be a modeling problem.

UPDATE (23Feb2010): Added 4nec2 sim runs for SemiChemE's Extended Boom modification.
Another On-Air Range test that did NOT find any frequency roll-off on Ch13: http://www.aa6g.org/Lp/tests.html
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Hi-VHF A-C Y-10-7-13 Dual-Driven Yagi
7. Hi-VHF A-C Y-10-7-13 Dual-Driven Yagi  (25Jan2011)
Antennacraft Y-10-7-13, 10-Element, Hi-VHF Dual-Driven Yagi analyzed using 4nec2.  Boom Length = 117.4-in + Ends.

Original 4nec2 file and measurements by tripelo on an antenna provided by re_nelson.
Note that the two Driven Elements are the SAME size with an IN-PHASE (not quite) QUARTER-WAVELENGTH feedline,
rather than different length elements with HALF-WAVELENGTH CROSSOVER feedline used in a Log-Yagi.

holl_ands 4nec2 mods: Autosegment(21), variable Rsrc to adjust AGT=1.0, decimal roundoffs and various RP/FR statement choices.

The first set of curves assume a Half-Element Boom Correction of 0.125-inch (tripelo's guess).
The second set of curves assumes ZERO Boom Correction, which is closer to the Top-Of-Boom derating per
discussion found in YA-1713 album.  Note 4nec2 predicted improvement in Ch13 Raw Gain & SWR....but predicted
Ch7 Raw Gain roll-off is about the same.

Ch7-12 Raw Gain = 7.5 to 12.8 dBi, but Rolloff on Ch13 May NOT be Real.
Ch7-12 SWR(300-ohms) Under 1.7, but Rise on Ch13 May NOT be Real.
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Hi-VHF A-C Y-10-7-13 plus 2 RRs & 3 Dirs
8. Hi-VHF A-C Y-10-7-13 plus 2 RRs & 3 Dirs  (20 Aug 2015)
Antennacraft Y-10-7-13 10-Element Dual-Driven Yagi PLUS two Additional Reflector Rods
and three Director Rods analyzed using 4nec2.  Boom Length = 149.7-in + Ends.

Additional Elements come from Front Boom and Rear Reflector Pair from re-purposed
MCM Stellar Labs 30-2475 8-El Folded Dipole Yagi, analyzed here:
Front of MCM Yagi attached "AS-IS" with NO CHANGES....NOT Re-Optimized Dimensions.

Ch7-12 Raw Gain = 9.6 to 14.0 dBi, but Roll-Off on Ch13 Might NOT be Real.
Ch7-12 SWR (300-ohms) under 2.5, but Rise on Ch13 May NOT be Real.

Compare to Original Y10-7-13 Performance:
Ch7-12 Raw Gain = 7.5 to 12.8 dBi, but Ch13 Rolloff May NOT be Real.
Ch7-12 SWR(300-ohms) Under 1.7, but Rise on Ch13 May NOT be Real.

UPDATE (21 Aug 2015): Rebuilt 4nec2 File, fixing a couple of very minor errors.
Although differences were negligible, I updated and reloaded ALL Images anyway.
Viewing 3D Model in EVAL *.html Performance File now displays correctly.
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