UHF 4th Order Sierpinski Arrowhead (Fractal) Bowtie analyzed using 4nec2.
Three feedpoint geometries were analyzed: 1) End-Fed Anti-Symmetric (mirrored on Centerpoint vice Z-Axis) provided best Raw Gain and SWR, but SWR was excessive on the lower frequencies, limiting the useful bandwidth. The sharp dive in the (Forward) Gain curve corresponds to when the Azimuthal Pattern changes into a four-leaf clover, with minimal Forward Gain...also note that Real Part of Impedance, R(ohm), nose dives down to only 25-ohms, resulting in a very high SWR peak. These severely limit the usable bandwidth.
2) End-Fed Symmetric (mirrored on Z-Axis) had poor Raw Gain and SWR identical to End-Fed Anti-Symetric.
3) Center-Fed Symmetric had poor Raw Gain as well as poor SWR.
These antennas would need to be Rescaled to match the desired operating band since they were very poor matches for existing UHF Band. SOURCE Wire length should them be varied to obtain best SWR.
Date(s): 21 Jan 2013. Album by holl_ands. 1 - 18 of 18 Total. 11024 Visits.
enlarge 66KB, 1024x1004 1 End-Fed Anti-Symmetric Fractal Bowtie 3D View
enlarge 335KB, 1024x1004 2 End-Fed Anti-Symmetric Fractal Bowtie Front View [1 big box = 1.25 inches]