FM ZigZag Antenna, similar to Triax FM Zigma, analyzed using 4nec2.
Triax FM Zigma Specs: Gain = -1.0 dBi, F/B Ratio = 0 dB, Beamwidth = +/- 45-deg (Horizontal Polarization) and +/- 180-deg (Vertical Pol.). Erroneously] "Length" [Width!!!] = 550-mm and "Width" [Height!!!] = 1140-mm: http://www.triax.co.uk/upload/gb_-_triax_main_catalogue_2009.pdf
Triax FM Zigma Dimensions: Height = 44.88-in, Width = 21.65-in, Separation = 2.0-in. Separation was a Guesstimate, based on Triax's picture. If it were 3.0-in, SWR is under 3.5 with negligible change in Gain.
Triax FM Zigma 4nec2 Results: For Vertically Polarized signals, the Azimuthal Pattern was close to Omni-directional, varying from -1.5 to -0.7 dBi across all angles and frequencies. However, for Horizontally Polarized signals, the pattern was Bi-Directional, with deep nulls to the sides (like a Folded Dipole), varying from -39 to -1.7 dBi.
Across all angles and frequencies, Total Raw Gain ranges from -1.5 to +2.4 dB (Horizontal + Vertical). SWR (300-ohms) is under 3.7.
============================================================================== A parameter search was conducted to find the dimensions for which the Vert. Pol. Gain was roughly equal to Horiz. Pol. Gain and hence provided optimal response to Circularly Polarized signals. Results are below.
Note that Cir. Pol. condition is only found in the Forward and Reverse directions due to Horiz. Pol. nulls on sides.
FM ZigZag 4nec2 Results: For Vertically Polarized signals, the Azimuthal Pattern was close to Omni-directional, varying from -2.5 to -0.4 dBi across all angles and frequencies. However, for Horizontally Polarized signals, the pattern was Bi-Directional, with deep nulls to the sides (like a Folded Dipole), varying from -37 to -1.1 dBi.
Across all angles and frequencies, Total Raw Gain ranges from -2.5 to +2.3 dB (Horizontal + Vertical). SWR (300-ohms) is under 3.7.
FYI: There were many nikiml python script solutions with SWR under 3.0, but NONE came close to Cir. Pol. condition.
30 Dec 201126 items5072 visitsAlbum by holl_ands
enlarge 43KB, 793x1024 1 Triax FM Zigma 3D View
enlarge 153KB, 623x1024 2 Triax FM Zigma Front View - 44.9-in High, 21.7-in Wide [1 big box = 5-inches]
enlarge 61KB, 213x1024 3 Triax FM Zigma Side View - 2-in Separation between Elements [1 big box = 5-inches]
enlarge 143KB, 1152x584 4 Triax FM Zigma FM TOTAL Raw Gain to REVERSE is more than FORWARD
enlarge 170KB, 1152x584 5 Triax FM Zigma FM SWR (300-ohms) is Under 3.7
enlarge 156KB, 1152x584 6 Triax FM Zigma FM Impedance
enlarge 337KB, 1024x1024 7 Triax FM Zigma Azimuthal Pattern at 87 MHz
enlarge 338KB, 1024x1024 8 Triax FM Zigma Azimuthal Pattern at 97 MHz
enlarge 339KB, 1024x1024 9 Triax FM Zigma Azimuthal Pattern at 103 MHz
enlarge 341KB, 1024x1024 10 Triax FM Zigma Azimuthal Pattern at 108 MHz
enlarge 70KB, 263x1024 11 Triax FM Zigma Top View - 2.0-in Separation between Elements [1 big box = 2.5-inches]
enlarge 26KB, 791x1024 12 Triax FM Zigma 4nec2 File
enlarge 35KB, 642x1024 13 FM ZigZag - Cir. Pol Fwd/Rev 3D View
enlarge 157KB, 686x1024 14 FM ZigZag - Cir. Pol Fwd/Rev Front View - 39-in Height, 22-in Width [1 big box = 5-inches]
enlarge 58KB, 225x1024 15 FM ZigZag - Cir. Pol Fwd/Rev Side View - 2-in Separation between Elements [1 big box = 5-inches]
enlarge 152KB, 1152x584 16 FM ZigZag - Cir. Pol Fwd/Rev FM TOTAL Raw Gain to REVERSE is more than FORWARD
enlarge 134KB, 1152x584 17 FM ZigZag - Cir. Pol Fwd/Rev FM TOTAL (Vert. + Horiz.) Raw Gain to SIDES is never below -2.5 dBi, despite Horiz. Pol. nulls.
enlarge 169KB, 1152x584 18 FM ZigZag - Cir. Pol Fwd/Rev FM SWR (300-ohms) is under 3.7
enlarge 156KB, 1152x584 19 FM ZigZag - Cir. Pol Fwd/Rev FM Impedance
enlarge 334KB, 1024x1024 20 FM ZigZag - Cir. Pol Fwd/Rev Azimuthal Pattern at 87 MHz
enlarge 333KB, 1024x1024 21 FM ZigZag - Cir. Pol Fwd/Rev Azimuthal Pattern at 91 MHz
enlarge 334KB, 1024x1024 22 FM ZigZag - Cir. Pol Fwd/Rev Azimuthal Pattern at 97 MHz
enlarge 334KB, 1024x1024 23 FM ZigZag - Cir. Pol Fwd/Rev Azimuthal Pattern at 103 MHz
enlarge 337KB, 1024x1024 24 FM ZigZag - Cir. Pol Fwd/Rev Azimuthal Pattern at 108 MHz
enlarge 26KB, 791x1024 25 FM ZigZag - Cir. Pol Fwd/Rev 4nec2 File
enlarge 65KB, 241x1024 26 FM ZigZag - Cir. Pol Fwd/Rev Top View - 2-in Separation between Elements [1 big box = 2.5-inches]
