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holl_ands | Home > Parabolic Antennas > Browse:Comparison Charts - ParabolicsCM4251 7-ft Parabolic + 2-Bay Refl FeedCM4251 Parabolic + 4-Wire FBmodCM-4251 Parabolic+FBmod - Bigger 2-BayCM4251 Parabolic+FBmod - Opt. 2-Bay 9-RRCM-4251 Parabolic+FBmod+8-El LPDACM-4251 Parabolic+FBmod+9-El LPDAUHF 2-m Parabolic + 8-El LPDA Feed
CM4251 Parabolic+FBmod - Opt. 2-Bay 9-RR UHF CM4251 Parabolic+FBmod (4-Wire Front/Back Mod) with OPTIMIZED 2-Bay Bowtie with 9 Reflector Rods analyzed using 4nec2.  [Additional runs needed to optimize number of RR's.] Nikiml's Python Optimization Scripts were used to find the "best" set of SEVEN variables: Bowtie Whisker Length, Tine Separation, Feedline Separation, Separation from Bowties to Reflector Rods, Reflector Rod Length, Rod-Rod Separation and Separation between Bowties and Center of Parabolic Reflector. For this initial run, Bowtie-Bowtie Spacing was fixed at 9.0-inches. Note how the 9 Reflector Rods don't cover the entire vertical height of the Bowties.  This is unexpected and may be due to either a trade-off re amount of incoming signal blockage or perhaps an inherent resonance (note location of highest & lowest RR directly behind the center of each Bowtie)...T.B.D. Addendum: Or perhaps the Optimizer was trying to adjust the Antenna Pattern for a more EVEN Illumination of the ENTIRE Parabolic Reflector.  Highest Gain was NOT the "Best". Date(s): 23 Mar 2013. Album by holl_ands. 1 - 16 of 16 Total. 5232 Visits.
enlarge 90KB, 694x1024 1 CM4251 Parabolic+FBmod - Opt. 2-Bay 9-RR 3D View enlarge 246KB, 991x1024 2 CM4251 Parabolic+FBmod - Opt. 2-Bay 9-RR Front View [1 large square = 12.5 inches] enlarge 143KB, 586x1024 3 CM4251 Parabolic+FBmod - Opt. 2-Bay 9-RR Top View [1 large square = 12.5 inches] enlarge 185KB, 1152x678 4 CM4251 Parabolic+FBmod - Opt. 2-Bay 9-RR UHF Raw Gain Max = 19.9 dBi Good F/B & F/R, except lower channels More mods to Parabolic Reflector should improve low freq Gain, F/B & F/R Ratios. enlarge 193KB, 1152x678 5 CM4251 Parabolic+FBmod - Opt. 2-Bay 9-RR UHF SWR (300-ohms) Under 2.5 enlarge 247KB, 1152x678 6 CM4251 Parabolic+FBmod - Opt. 2-Bay 9-RR UHF Impedance enlarge 300KB, 1024x1024 7 CM4251 Parabolic+FBmod - Opt. 2-Bay 9-RR Azimuthal Pattern at 470 MHz enlarge 301KB, 1024x1024 8 CM4251 Parabolic+FBmod - Opt. 2-Bay 9-RR Azimuthal Pattern at 530 MHz enlarge 299KB, 1024x1024 9 CM4251 Parabolic+FBmod - Opt. 2-Bay 9-RR Azimuthal Pattern at 590 MHz enlarge 300KB, 1024x1024 10 CM4251 Parabolic+FBmod - Opt. 2-Bay 9-RR Azimuthal Pattern at 650 MHz enlarge 299KB, 1024x1024 11 CM4251 Parabolic+FBmod - Opt. 2-Bay 9-RR Azimuthal Pattern at 698 MHz enlarge 300KB, 1024x1024 12 CM4251 Parabolic+FBmod - Opt. 2-Bay 9-RR Azimuthal Pattern at 758 MHz enlarge 302KB, 1024x1024 13 CM4251 Parabolic+FBmod - Opt. 2-Bay 9-RR Azimuthal Pattern at 806 MHz enlarge 283KB, 1024x892 14 CM4251 Parabolic+FBmod - Opt. 2-Bay 9-RR Front View DETAIL [1 large square = 2.5 inches] enlarge 132KB, 579x1024 15 CM4251 Parabolic+FBmod - Opt. 2-Bay 9-RR Side View [1 large square = 12.5 inches] enlarge 52KB, 791x1024 16 CM4251 Parabolic+FBmod - Opt. 2-Bay 9-RR 4nec2 File
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