2.
UHF Four Unequal Diamonds - 13 Refl Rods (3 May 2013)UHF Four Unequal Diamonds with 13 Reflector Rods analyzed using 4nec2.
Active Element dimensions were same as for Dnes 11 Reflector Rod version, except that "SKALE=0.97"
factor was adjusted so that Max Gain was closer to 698 MHz, the top of the New UHF Band.
Rod Length, Rod-Rod Separation and Rod-Element Separation were then determined using nikiml's
Python Optimization Scripts.
Resulting design met my desired goals of F/R Ratio larger than 15 dB and F/B Ratio larger than 20 dB.
Raw Gain increases from 10.5 to 11.5 dBi with SWR under 2.4 and CONSTANT Beamwidth of 70-deg
from 470 MHz up thru 758 MHz, making it an unusually WIDE Beamwidth Antenna.
Large Diamond Element Lengths: 5.47 (fm Feedpoint) & 6.21. Small Diamond Element Lengths: 4.74.
Feedpoint Gap = 2 inches; Large Diamond Outer Apex: Y=4.85, Z=3.88; Crossover: Xhop=0.5, Z=7.76;
Small Diamond Outer Apex: Y=2.72, Z=11.64; Max Z=15.52.
Reflector Rod Length = 13.75 inches, Rod-Rod Spacing = 1.88 inches, Rod-Element Separation = 3.68 inches. |
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