UHF Free Form 4-Bay Bowtie (FF4 - NO Reflector) analyzed using 4nec2 after using nikiml's Python Optimization Scripts to determine "best" dimensions for UHF (Only). Essentially ALL parameters were allowed to independently vary over a wide range of values in the Optimization. Height=38.4-inches, Width=26.8-inches.
ONLY Constraints were Element & Feedline Radius (AWG10), Conductivity (Copper), "Hop=1-in" Wire Separation at the Feedline Crossover point, same Feedline Separation Top-to-Bottom, NO Forward Sweep in the (FLAT) Bowties and Left/Right plus Top/Bottom Symmetry, allowing different Inner & Outer Bowties.
UHF Raw Gain = 9.7 to 12.6 dBi and SWR (300-ohms) under 2.6. Hi-VHF Raw Gain = 3.5 dBi and SWR (300-ohms) = 2.2 to 3.9 [A bit Excessive except Ch7-8.]
ASSUMED DIMENSIONS (All in inches): Rbow=0.051 = AWG10 Element Wire size [AWG12 thru AWG8 are also good] Rfeed=0.051 = AWG10 Feedline Wire size [AWG12 thru AWG8 are also good] Hop=1.0 = X-Axis Separation at Crossover
OPTIMIZED DIMENSIONS (All in inches, may round to nearest 1/8-in): ZBowII=12.57 = Distance between the Centers of the two INNER Bowties ZBowOI=9.86 = From Center of INNER Bowtie to Center of OUTER Bowtie BowLeni=11.60 = INNER Bow Whisker Length (lose some in bend) BowLeno=8.01 = OUTER Bow Whisker Length (lose some in bend) TineSepi=6.61 = INNER Bow Tine Separation TineSepo=6.14 = OUTER Bow Tine Separation FeedSep=4.39 = Separation between two FEEDLINE wires ZCross=1.25 = From Center of Feedline Cross-Over to Center of OUTER Bowtie
Date(s): 2 Nov 2013. Album by holl_ands. 1 - 22 of 22 Total. 7276 Visits.
enlarge 72KB, 721x1024 1 UHF Free-Form 4-Bay Bowtie - NO Refl 3D View
enlarge 197KB, 710x1024 2 UHF Free-Form 4-Bay Bowtie - NO Refl Front View [1 large square = 5-inches]
enlarge 70KB, 231x1024 3 UHF Free-Form 4-Bay Bowtie - NO Refl Top View [1 large square = 2.5-inches]
enlarge 160KB, 1152x686 4 UHF Free-Form 4-Bay Bowtie - NO Refl UHF Raw Gain = 9.7 to 12.6 dBi
enlarge 190KB, 1152x686 5 UHF Free-Form 4-Bay Bowtie - NO Refl UHF SWR (300-ohms) Under 2.6