 1.
UHF 3Bay Fat Dipole + 16 RR  OPT (21 Aug 2014)UHF 3Bay Fat Dipole + 16 Reflector Rods analyzed using 4nec2 after determining dimensions using nikiml's Python Optimization Scripts. Reflector RodtoRod Separation was presumed to be 2in for an existing set of 4 ea Reflector SubAssemblies with 4RR each.
UHF Raw Gain = 11.8 to 12.9 dBi, F/B & F/R Ratio Min = 18.8 dB and SWR (300ohms) under 2.9. HiVHF Raw Gain FORWARD = 8 to 9 dBi on Ch913 and TO REAR = 6 to 8 dBi on Ch78 but SWR is Excessive. [Can reduce UHF SWR under 2.7 if RS=4.8in with only 0.3 dB Loss on 698 MHz.]
ASSUMED DIMENSIONS (all in inches): Rdip=0.4375 = Radius of Dipole Elements (7/8in O.D. in this model) Rfeed=0.06425 = Radius of Feedline (AWG8 in this model) DSwp=0 = Dipole Forward Sweep [If any, zero in this model] Hop=1.0 = Separation at Crossovers RR=2.0 = Reflector RodtoRod Separation Rrod=0.1875 = Radius of Reflector Rods
OPTIMIZED DIMENSIONS (rounded to nearest 1/8inch): DDSep=10.5 = DipoleToDipole Separation DLen=5.875 = Dipole HalfLength FeedSep=2.75 = Separation between two FEEDLINE wires ZCross=2.0 = From Center of Feedline CrossOver to Center of OUTER Dipoles RS=4.5 = Reflector Rod Separation behind Active Elements YRod=14.875 = Reflector Rod HalfLengths 
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 2.
UHF 3Bay Fat Dipole + 12RR  OPT (20 Aug 2014)UHF 3Bay Fat Dipole with 12 Reflector Rods analyzed using 4nec2 after determining dimensions using nikiml's Python Optimization Scripts. Reflector RodtoRod Separation was presumed to be 2in for an existing set of 3 ea Reflector SubAssemblies with 4RR each.
UHF Raw Gain = 10.9 to 12.5 dBi, F/B & F/R Ratio Min = 17.7 dB and SWR (300ohms) under 2.7. HiVHF Raw Gain Forward is low but usable on Ch79 & Ch13, but toward REAR is higher on Ch1012. HiVHF SWR (300ohms) is Excessive.
ASSUMED DIMENSIONS (all in inches): Rdip=0.4375 = Radius of Dipole Elements (7/8in O.D. in this model) Rfeed=0.06425 = Radius of Feedline (AWG8 in this model) DSwp=0 = Dipole Forward Sweep [If any, zero in this model] Hop=1.0 = Separation at Crossovers RR=2.0 = Reflector RodtoRod Separation Rrod=0.1875 = Radius of Reflector Rods
OPTIMIZED DIMENSIONS (rounded to nearest 1/8in): DDSep=10.25 = DipoleToDipole Separation DLen=5.875 = Dipole HalfLength [Excludes Feedline Gap] FeedSep=3.375 = Separation between FEEDLINE wires ZCross=1.75 = From Center of Feedline CrossOver to Center of OUTER Dipoles RS=4.5 = Reflector Rod Separation behind Hourglass YRod=13.5 = Reflector Rod HalfLengths
ERRATA (21Aug2014): Uploaded Corrected 4nec2 File, which had "16RR" rather than "12RR" in Comments. 
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UHF 3Bay FAT Dipoles + 12 Pair RR  OPT (1 Sep 2014)UHF 3Bay FAT Dipoles with 12 Pair of Reflector Rods (narrow Gap in the middle) analyzed using 4nec2 after determining Dimensions using nikiml's Python Optimization Scripts.
Compared to 12RR version with NO middle Gap, this version improved Raw Gain by 0.8 dB on lowest frequencies and 0.4 dB on highest frequencies. However SWR, F/B & F/R degraded. In HiVHF Band, the usable Forward Gain in the NOMIDDLEGAP version on Ch79 & Ch13 moved to the REAR, now being consistent with Gain on other HiVHF Channels. SWR is still EXCESSIVE.
HOWEVER, note that when (and if) I rerun this Optimization with a revised Target Function to hopefully adjust SWR below desired limit of 2.7, Gain advantage will no doubt shrink.
UHF Raw Gain = 11.7 to 12.9 to 12.8 dBi, F/B & F/R Min = 12.1 dB and SWR (300ohms) under 3.1. HiVHF Raw Gain = 5.9 to 7.3 dBi TO REAR, F/B & F/R Min = 6.1 dB, but SWR is EXCESSIVE. HiVHF Raw Gain FORWARD is Very Poor.
ASSUMED DIMENSIONS (all in inches): Rdip=0.4375 = Radius of Dipole Elements (7/8in O.D. in this model) Rfeed=0.06425 = Radius of Feedline (AWG8 in this model) DSwp=0 = Dipole Forward Sweep [If any, zero in this model] Hop=1.0 = Separation at Crossovers RR=2.0 = Reflector RodtoRod Separation Rrod=0.1875 = Radius of Reflector Rods
OPTIMIZED DIMENSIONS (rounded to nearest 1/8in): DDSep=9.0 = DipoleToDipole Separation DLen=7.25 = Dipole HalfLength [Excludes Feedline Gap] FeedSep=3.25 = Separation between FEEDLINE wires ZCross=2.0 = From Center of Feedline CrossOver to Center of OUTER Dipoles RS=4.25 = Reflector Rod Separation behind Hourglass YRod=17.0 = Reflector Rod HalfLengths Rgap=0.25 = Gap between Reflector Rod Pairs 
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 4.
WG HD4400 4Bay Dipole  NO Reflector (5 May 2017)Winegard HD4400 (aka PR4400) 4Bay Dipoles with NO Reflector Rods analyzed using 4nec2.
UHF Raw Gain  7.5 to 10.1 dBi and SWR (300ohms) under 3.5. HiVHF Raw Gain  4.08 to 4.15 dBi and SWR (300ohms) = 45.6 to 3.2 is EXCESSIVE.
Based on Ken Nist's w4400.ez EZNEC model (converted to 4nec2): http://www.hdtvprimer.com/SIMS/ 
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 5.
WG HD4400 4Bay Dipole with Reflector (4 Jun2012)Winegard HD4400 (aka PR4400) 4Bay Dipoles with 9 Reflector Rods analyzed using 4nec2.
UHF Raw Gain = 12.7 to 15.1 dBi, F/B & F/R Min = 11.0 dB and SWR (300ohms) under 2.3.
Based on Ken Nist's w4400.ez EZNEC model (converted to 4nec2): http://www.hdtvprimer.com/SIMS/ 
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 6.
UHF 4Bay Fat Dipoles + Grid Reflector (20 Apr 2014)UHF 4Bay Fat Dipoles + Grid Reflector was modeled using 4nec2 file posted by kakar133 and then modified for 3/4Wavelenght Long Transmission Lines connected to a Common Simulated SOURCE.
UHF Raw Gain = 11.0 to 13.5 dBi, F/R & F/B Min = 17.5 dB and SWR (300ohms) under 2.0.
Gain was significantly lower than WG PR4400 (see 4nec2 results) and Characteristic Impedance was only 75ohms, requiring the use of a 1:1 Balun, e.g. UnEqual Length Coax Balun: http://www.hamradio.me/antennas/coaxvelocityfactor.html 
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 7.
UHF Vertical 8Bay Dipole  NO Reflector (13 Feb 2013)UHF Vertical 8Bay using FAT Dipoles (NO Reflector) analyzed using 4nec2. Dimensions per Bouval's DIY posts starting with this one: http://www.digitalhome.ca/forum/showthread.php?p=1469742 Original (9.75"x9.625"): SWR Max = 3.1. Max Raw Gain = 14 dBi, but significant Gain Loss on channels in mid40's & above.
Mod1 (6.75"x9.625"): First optimization to fix Gain Loss problem considered simply cutting off the Dipole Tube ends . This yielded a fairly flat frequency response curve, except for some loss on lowest freqs and higher SWR on highest freqs. Mod1: SWR Max = 3.3. Raw Gain = 9.8 dBi (470 MHz), 12.0 (674 MHz), 11.0 (698 MHz). So a classic tradeoff of Gain for wider Bandwidth. Mod1 provided higher Gain on 698 MHz than Mod2a or Mod2b below.
Mod2: Second optimization found optimum Dipole Tube length while modifying the Feedline Separation and position of the Crossover relative to each OUTER Dipole. Bouval's DipoletoDipole Separation=9.625in was NOT changed.
By adjusting optimization parameters it is possible to influence the relative importance of Gain vs SWR: Mod2a (7.0"x9.625"): SWR Max = 3.2. Raw Gain = 9.8 dBi (470 MHz), 12.0 (674 MHz), 11.0 (698 MHz). Mod2b (8.0"x9.625"): SWR Max = 2.1. Raw Gain = 8.7 dBi (470 MHz), 13.2 (674 MHz), 8.7 (698 MHz). So Mod2a provides "flattest" freq response while Mod2B provides highest Max Gain but at expense of high/low freqs.
Mod3: Third optimization found optimum Dipole Tube length while modifying the Feedline Separation and position of the Crossover relative to each OUTER Dipole. DipoletoDipole Separation was also allowed to change in this more generalized optimization search process to compare an "optimum" configuration to the above alternatives. To minimize Azimuthal Pattern asymmetries, Crossovers alternate as to whether Right or Left Feedline Wire hops positive or negative on XAxis.
Provides excellent SWR with more Gain on highest freqs to overcome extra loss in the Balun, Coax and (if used) RF Splitter(s), although maybe more than needed for a mastmounted Preamp with only Balun Loss a significant factor. Mod3 (8.0"x8.5"): SWR Under 1.8. Raw Gain = 9.1 dBi (470 MHz), Max = 13.8 (686 MHz), 13.4 (698 MHz). 
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 8.
UHF Vertical 8Bay Dipoles + 43RR (7 Aug 2014)UHF Vertical 8Bay Dipole Array with 43 Reflector Rods analyzed using 4nec2 after Dimensions determined using nikiml's Python Optimization Scripts.
UHF Raw Gain = 13.5 to 17.0 to 15.1 dBi, F/B & F/R Ratio Min = 18.3 dB and SWR (300ohms) under 2.4. Crossover details must be exactly copied to maintain pattern symmetry.
ASSUMED DIMENSIONS (in inches): Rdip=0.4375 = Radius of Dipole Elements (7/8in O.D.) Rfeed=0.06425 = Radius of Feedlines (AWG8) Rrod=0.1875 = Radius of Reflector Rods (3/8in O.D.) Hop=1.0 = XAxis Separation at the CrossOver Cond=2e+07 = Conductivity for Aluminum DSwp=0 = Dipole Forward Sweep (NOT USED IN THIS MODEL]
OPTIMIZED DIMENSIONS (in inches, rounded to nearest 1/8in): DDSep=9.37 = DipoleToDipole Separation DLen=6.65 = Dipole HalfLength (JUST THE TUBE) FeedSep=2.5 = Separation between two FEEDLINE wires ZCross=1.39 = From Center of Feedline CrossOver to Center of OUTER Dipoles RS=4.16 = Reflector Rod Separation behind Dipoles RR=1.74 = Reflector RodtoRod Separation YRod=18.20 = Reflector Rod HalfLengths 
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 9.
UHF Vert 8Bay Dipole + 43 Pair RR  OPT (1 Sep 2014)UHF Vertical 8Bay FAT Dipole with 43 Pairs of Reflector Rods analyzed using 4nec2 after determining Dimensions using nikiml's Optimization Scripts. For some unknown reason, HiVHF analysis refused to run correctly, even after trying various AUTOSEG(xx) values.
UHF Raw Gain = 13.4 to 17.1 to 16.2 dBi, F/B & F/R Min = 14.3 dB and SWR (300ohms) under 3.1.
Compared to NOMIDDLEGAP version, Raw Gain improved by an inconsequential 0.1 dB except on the highest frequencies it improved by 0.8 dB. OTOH, hote that SWR, F/B & F/R Ratio were degraded.
HOWEVER, note that when (and if) I rerun this Optimization with a revised Target Function to hopefully adjust SWR below desired limit of 2.7, Gain advantage will no doubt shrink.
ASSUMED DIMENSIONS (in inches): Rdip=0.4375 = Radius of Dipole Elements (7/8in O.D.) Rfeed=0.06425 = Radius of Feedlines (AWG8) Rrod=0.1875 = Radius of Reflector Rods (3/8in O.D.) Hop=1.0 = XAxis Separation at the CrossOver Cond=2e+07 = Conductivity for Aluminum DSwp=0 = Dipole Forward Sweep (NOT USED IN THIS MODEL]
OPTIMIZED DIMENSIONS (in inches, rounded to nearest 1/8in): DDSep=9.0 = DipoleToDipole Separation DLen=7.875 = Dipole HalfLength (JUST THE TUBE) FeedSep=2.125 = Separation between two FEEDLINE wires ZCross=1.375 = From Center of Feedline CrossOver to Center of OUTER Dipoles RS=4.75 = Reflector Rod Separation behind Dipoles RR=1.5 = Reflector RodtoRod Separation YRod=16.785 = Reflector Rod HalfLengths Rgap=0.25 = Gap Between each Reflector Rod Pair 
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 10.
Winegard HD8800 8Bay FAT Dipoles (20 Jan 2017)Winegard HD8800 (aka PR8800) 8Bay FAT Dipoles analyzed using 4nec2.
EZNEC File was downloaded from Ken Nist's HDTVPrimer, Comparing Antennas Webpage: http://www.hdtvprimer.com/antennas/comparing.html [see SIMS link at top] After importing into 4nec2, Ken Nist's INCORRECTLY configured Combining Feedline was Deleted and Replaced by Dual SOURCE "EX" Statements and AutoSegmented.
Ken Niss made a mistake in the Input Feedline Structure, Incorrectly trying to Emulate what an RF Combiner would do, resulting in wildly inaccurate SWR and hence Net Gain results. An RF Combiner matches all Interfaces, whereas Ken's Combiner Network was a simple SHORT. I have now fixed this problem, so Net Gain is only slightly lower than Raw Gain curve.
Note that RF Combiner has a "typical" Insertion Loss of about 0.5 dB in HiVHF Band and 1.0 to 1.5+ dB in UHF Band, increasing with Frequency....which REDUCES the fol. Results:
UHF Raw Gain = 13.8 to 16.5 dBi and F/B & F/R Minimum = 12.5 dB with SWR (300ohms) Under 2.3. Raw Gain on Upper Channels is about 1 dB more than shown in HDTVPrimer and Net Gain is MUCH better, since SWR<2.3 results in Net Gain Loss on Ch14 of only 0.7 dB and
much less for remainder,
no doubt due to eliminating the Feedline Short.
Note that Elevation Pattern Charts showing NULL at about 4045 degrees. 
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