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 holl_ands | Home > Multi-Diamond Antennas  
Multi-Diamond Antennas
Multiple Diamond Analyzed using 4nec2.  Similar to Bi-Quad, except with additional Diamond shaped sections.
Date(s): 30 Apr 2013. 1 - 3 of 3 Total. Shared
UHF Four-Unequal-Diamonds - 11 Refl Rods
1. UHF Four-Unequal-Diamonds - 11 Refl Rods  (30 Apr 2013)
UHF Four-Unequal-Diamonds (aka Double Bi-Quad) with 11 Reflector Rods analyzed using 4nec2.
Dimensions per 4nec2 file prepared by Walter Dnes for Model X-150:

Note that this is based on the old Italian Fracarro PU-4 Panel Antenna, which had a Reflector Grid instead.

Provides very flat Gain across all of New UHF Band with Max = 11.4 dBi & Min = 10.9 with SWR Under 1.5.
F/B and F/R Ratios are Excellent, except for lowest frequencies.

Hi-VHF Gain is a bit less than Rabbit Ears (even less in the Forward direction) with Excessive SWR.
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UHF Four Unequal Diamonds - 13 Refl Rods
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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UHF Four-UnEqual-Diamonds CutEnds - 13RR
3. UHF Four-UnEqual-Diamonds CutEnds - 13RR  (5 Apr 2013)
UHF Four-Unequal-Diamonds with CUT-ENDS and 13 Reflector Rods analyzed using 4nec2.

Nikiml's Python Optimization Scripts were used to find the best values for ALL of the SYmbol variables in Dnes
original 4nec2 file which would provide highest Raw Gain consistent with low SWR and good F/B & F/R Ratios.
6635 Visits
21 Images
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