FM Vertical Folded Dipole TRUE-OMNI-Directional Antenna with Vertical Polarization analyzed using 4nec2. Details on building a Horizontal Folded Dipoles (rotated 90-deg) can be found here: http://imageevent.com/holl_ands/loops/folded http://imageevent.com/holl_ands/loops/vhffoldeddipole Note that increasing Separation between the Elements requires reduced Length to compensate.
Presumes a HICT (Half-Inch Copper Tubing, Actual O.D. = 0.569-in) and 4-in Separation between the Folded Elements, Optimum Overall Length = 55.0-in.
Vertically Polarized Raw Gain is not quite Omni-Directional, ranging from +1.7 to +2.6 dBi, depending on angle & frequency. SWR (300-ohms) is under 2.0 across the entire FM Band.
17 Dec 201115 items8868 visitsAlbum by holl_ands
enlarge 28KB, 531x1024 1 FM Vertical Dipole Omni 3D View
enlarge 42KB, 154x1024 2 FM Vertical Dipole Omni Front View [1 big box = 5-inches]
enlarge 63KB, 227x1024 3 FM Vertical Dipole Omni Side View [1 big box = 5-inches]
enlarge 165KB, 1152x584 4 FM Vertical Dipole Omni FM Raw Gain FORWARD (Vert. Only) REARWARD Gain is a few tenths of a dB lower.
enlarge 148KB, 1152x584 5 FM Vertical Dipole Omni FM Vert. Raw Gain To SIDE (0-deg)
enlarge 190KB, 1152x584 6 FM Vertical Dipole Omni FM SWR (300-ohms) Under 2.0
enlarge 306KB, 1024x1024 7 FM Vertical Dipole Omni Azimuthal Pattern at 87 MHz
enlarge 303KB, 1024x1024 8 FM Vertical Dipole Omni Azimuthal Pattern at 91 MHz
enlarge 305KB, 1024x1024 9 FM Vertical Dipole Omni Azimuthal Pattern at 97 MHz
enlarge 307KB, 1024x1024 10 FM Vertical Dipole Omni Azimuthal Pattern at 103 MHz
enlarge 309KB, 1024x1024 11 FM Vertical Dipole Omni Azimuthal Pattern at 108 MHz
enlarge 112KB, 1152x612 12 FM Vertical Dipole Omni Top View [1 big box = 1.25-inches]
enlarge 149KB, 1152x584 13 FM Vertical Dipole Omni FM Impedance
enlarge 26KB, 791x1024 14 FM Vertical Dipole Omni 4nec2 File
enlarge 297KB, 1024x1019 15 Vertical Folded Dipole for FM Band Slightly more Gain away from the Feedpoint.
