FM ESS Curve Quasi-Omni Antennas analyzed using 4nec2. Although Vertical Polarization pattern was mostly Omni-directional, the Horizontal pattern was Bi-Directional, with deep nulls to the sides.
Fracarro ANT1200A specifications list Height=38in (96-cm) and Width=30-in (77-cm) with 75-ohm Type "F" output (e.g. 300:75-ohms Balun). Fracarro claims Max Gain=2.1 dB?, F/B Ratio="OMNI", -3 dB Beamwidth=360-deg and Return Loss=-16 dB (SWR Under 1.38): http://www.fracarro.es/download/prodottitvsat/Aerials/FM_SERIES.pdf
A 4nec2 model was constructed, assuming two variable length (="Middle") wires at the mid-point with Z=0 (along Y-Axis). At either end of the Middle wires are quarter-circle arcs with Radius-Of-Curvature=0.5*(Width-Middle), to which are attached straight up-and-down wires extending to +/- Height/2. Actual dimensions may be slightly different, e.g. Separation between ESS's may be (inconsequential) 2.5-in vice 2.0-in.
The "optimum" length for "Middle" (7.6-in) was found by running a nikiml optimization script on the 4nec2 file (mostly Min SWR).
Fracarro 4nec2 Results: For Vertically Polarized signals, the Azimuthal Pattern was close to Omni-directional, varying from -4.4 to -1.4 dBi across all angles and frequencies. However, for Horizontally Polarized signals, the pattern was Bi-Directional, with deep nulls to the sides, varying from -34 to +0.1 dBi.
Across all angles and frequencies, Total Raw Gain ranges from -4.4 to +2.3 dB (Horizontal + Vertical). SWR was excellent, between 1.3 in middle and 2.7 at band edges.
============================================================================= Dipol A0222/A0223 specifications are very sparse. Gain curve starts at -3 dBi, rising to -1 at mid-high frequencies. Impedance is 300-ohm (no Balun) and they (erroneous) indicate that it has Horiz. and Vert. (wrong) polarization. Size is indeterminate: http://www.dipolnet.com/estore-antennas-fm,4346.htm
Blowing up and comparing the photo of the Dipol A0222/A223 to the Fracarro ANT1200A reveals that they are very similar, except for being mirror images about the Z-Axis. After reversing the sign of all Y-Axis coordinates in the Fracarro 4nec2 file, it was compared to the Dipol photo, which appears to be slightly shorter, wider and smaller Separation between the two ESS's compared to the Fracarro. 4nec2 file was adjusted to best match Dipol's photo: Height=37in, Width=33in, Middle=6in & Separation=2-in.
Dipol 4nec2 Results: For Vertically Polarized signals, the Azimuthal Pattern was close to Omni-directional, varying from -5.1 to -1.9 dBi across all angles and frequencies. However, for Horizontally Polarized signals, the pattern was Bi-Directional, with deep nulls to the sides, varying from -36 to +0.4 dBi.
Across all angles and frequencies, Total Raw Gain ranges from -5.1 to +2.4 dB (Horizontal + Vertical). SWR was excellent, between 1.3 in middle and 2.5 at band edges.
27 Dec 201131 items7341 visitsAlbum by holl_ands
enlarge 50KB, 721x1024 1 FM ESS Curve - Similar to Fracarro ANT1200A 3D View
enlarge 208KB, 905x1024 2 FM ESS Curve - Similar to Fracarro ANT1200A Front View [1 big box = 5-inches]
enlarge 62KB, 221x1024 3 FM ESS Curve - Similar to Fracarro ANT1200A Side View [1 big box = 5-inches]
enlarge 34KB, 640x1024 4 FM ESS Curve - Fracarro ANT1200A 3D View - Picture from Fracarro Catalog
enlarge 28KB, 791x1024 5 FM ESS Curve - Similar to Fracarro ANT1200A 4nec2 File
enlarge 68KB, 270x1024 6 FM ESS Curve - Similar to Fracarro ANT1200A Top View [1 big box = 5-inches]
enlarge 140KB, 1152x584 7 FM ESS Curve - Similar to Fracarro ANT1200A FM Total Raw Gain to REAR (270-deg) slightly higher than to FRONT (90-deg)
enlarge 136KB, 1152x584 8 FM ESS Curve - Similar to Fracarro ANT1200A FM Total Raw Gain to SIDE (0-deg) remains above -4.3 dBi (Horizontal + Vertical Polarization)
enlarge 173KB, 1152x584 9 FM ESS Curve - Similar to Fracarro ANT1200A FM SWR (300-ohms) 1.2 to 2.7
enlarge 153KB, 1152x584 10 FM ESS Curve - Similar to Fracarro ANT1200A FM Impedance
enlarge 339KB, 1024x1024 11 FM ESS Curve - Similar to Fracarro ANT1200A Azimuthal Pattern at 87 MHz
enlarge 339KB, 1024x1024 12 FM ESS Curve - Similar to Fracarro ANT1200A Azimuthal Pattern at 91 MHz
enlarge 339KB, 1024x1024 13 FM ESS Curve - Similar to Fracarro ANT1200A Azimuthal Pattern at 97 MHz
enlarge 337KB, 1024x1024 14 FM ESS Curve - Similar to Fracarro ANT1200A Azimuthal Pattern at 103 MHz
enlarge 340KB, 1024x1024 15 FM ESS Curve - Similar to Fracarro ANT1200A Azimuthal Pattern at 108 MHz
enlarge 73KB, 1009x1024 16 FM ESS Curve - Similar to Dipol A0222 + A0223 3D View
enlarge 213KB, 929x1024 17 FM ESS Curve - Similar to Dipol A0222 + A0223 Front View [1 big box = 5-inches]
enlarge 61KB, 232x1024 18 FM ESS Curve - Similar to Dipol A0222 + A0223 Side View [1 big box = 5-inches]
enlarge 81KB, 1024x832 19 FM ESS Curve - Dipol A0222 + A0223 Picture from Dipol Catalog
enlarge 29KB, 791x1024 20 FM ESS Curve - Similar to Dipol A0222 + A0223 4nec File
enlarge 72KB, 282x1024 21 FM ESS Curve - Similar to Dipol A0222 + A0223 Top View [1 big box = 5-inches]
enlarge 141KB, 1152x584 22 FM ESS Curve - Similar to Dipol A0222 + A0223 FM Total Raw Gain to REAR (270-deg) slightly higher than to FRONT (90-deg)
enlarge 134KB, 1152x584 23 FM ESS Curve - Similar to Dipol A0222 + A0223 FM Total Raw Gain to SIDE (0-deg)
enlarge 174KB, 1152x584 24 FM ESS Curve - Similar to Dipol A0222 + A0223 FM SWR (300-ohms) is Excellent 1.3 to 2.5
enlarge 170KB, 1152x584 25 FM ESS Curve - Similar to Dipol A0222 + A0223 FM SWR (300-ohms) is High to Excessive 3.0 to 8.5
enlarge 153KB, 1152x584 26 FM ESS Curve - Similar to Dipol A0222 + A0223 FM SWR Impedance
enlarge 339KB, 1024x1024 27 FM ESS Curve - Similar to Dipol A0222 + A0223 Azimuthal Pattern at 87 MHz
enlarge 338KB, 1024x1024 28 FM ESS Curve - Similar to Dipol A0222 + A0223 Azimuthal Pattern at 91 MHz
enlarge 338KB, 1024x1024 29 FM ESS Curve - Similar to Dipol A0222 + A0223 Azimuthal Pattern at 97 MHz
enlarge 337KB, 1024x1024 30 FM ESS Curve - Similar to Dipol A0222 + A0223 Azimuthal Pattern at 103 MHz
enlarge 340KB, 1024x1024 31 FM ESS Curve - Similar to Dipol A0222 + A0223 Azimuthal Pattern at 108 MHz
