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holl_ands | Home > Omni & Quasi-Omni Directional Antennas > Browse:FM Flat-Swept SBGH H-POL OMNI-PLUSFM TRIAD 4xRectangular-Loops H-OMNI-PLUSFM Goalkeeper Quad-Trap+Spurs Quasi-OMNIFM TRIAD Array of Dipoles H-OMNIFM Double-Hoop H-POL OMNIFM Double-Hoop + Vertical-Dipole OutsideFM Double-Hoop + Vertical-FD-OutsideFM Double-Hoop + Vert. Dipole In CenterFM Double-Hoop + Vertical-FD-In-CenterFM Double-Hoop + Vertical Whip OutsideFM Vertical Folded Dipole VPOL TRUE-OMNIFM Vertical Stick Dipole V-POL TRUE-OMNIFM + VHF Discone V-POL TRUE-OMNIFM Monopole Whip over Groundplane OMNIFM Turnstile QuasiOMNI Antennacraft FMSSFM Turnstile Quasi-Omni - AlternateFM Turnstile - A-C FMSS RotatedFM ESS Curves - Fracarro & DipolFM ZigZag - Triax FM ZigmaFM Right Circular Folded Dipole PairFM Cycloid Dipole - Circular Polarized490 MHz Flat-Swept SBGH H-POL OMNI-PLUS490 MHz Flat-Swept SBGH OMNI + TOP-HAT490 MHz 3-Dipole TRIAD Array H-POL OMNI490 MHz Crossed-Dipoles + One TL - OMNI490 MHz Crossed-Dipoles, 2 Unequal TLs490 MHz 7-El Yagi TRIAD H-POL OMNI-PLUS490 MHz 4El Yagi Triad H-POL True-OMNI490 MHz Collinear Helical HPOL OMNI-PLUS490 MHz Double Diamond H-POL Quasi-OMNIUHF Vertical Folded Dipole V-POL OMNIUHF SBGH H-POL OMNI-PLUS by nikimlUHF Hoverman Type 1 H-POL Quasi-OmniUHF M4 (10x9.5) Twisted 4-Bay Quasi-OMNIUHF 2xM4 Twisted 8-Bay - Quasi-OMNIHi-VHF Goalkeeper Quad-Trapezoid+SpursHi-VHF Monopole Whip V-POL TRUE-OMNIHi-VHF Vertical Folded Dipole OMNICh2-69 Crossed Loops 90-deg Phase ShiftCh2-69 + FM Crossed Loops - UVOX-22m "Classic" 3QWL+QWL J-Pole
490 MHz Collinear Helical HPOL OMNI-PLUS 490 MHz Horizontally Polarized Collinear (Axial Mode) Helical Antennas  were analyzed using 4NEC2. 1) 15-Turns above a 36x36-in Square Grid Ground Plane: It is an OMNI-PLUS type [with and AT LEAST 0 dBd Gain = 2.15 dBi in ALL directions].... and significantly MORE in some directions. In order to provide improved Look Down Angle Coverage, the Antenna would be mounted Upside-Down. Azimuthal Gain Min = 4.2 dBi and Gain Max = 6.3 dBi with SWR (200-ohms) = 1.4 (very Flat). A 4:1 Balun would be used to connect to 50-ohm Coax and Transmitter. 2) T.B.D. Date(s): 10 Mar 2016. Album by holl_ands. 1 - 13 of 13 Total. 1914 Visits.
enlarge 176KB, 842x1024 1 490 MHz H-Pol 15-Turn Helical + Square Grid enlarge 194KB, 579x1024 2 490 MHz H-Pol 15-Turn Helical + Square Grid Front View [1 Large Square = 12.5-inches] enlarge 673KB, 1011x1024 3 490 MHz H-Pol 15-Turn Helical + Square Grid Top View [1 Large Square = 5-inches] enlarge 129KB, 1024x895 4 490 MHz H-Pol 15-Turn Helical + Square Grid 3D Gain for Horizontal Polarization enlarge 126KB, 1024x899 5 490 MHz H-Pol 15-Turn Helical + Square Grid 3D Gain for Vertical Polarization enlarge 129KB, 1024x892 6 490 MHz H-Pol 15-Turn Helical + Square Grid 3D Gain for Total Polarization enlarge 276KB, 1152x703 7 490 MHz H-Pol 15-Turn Helical + Square Grid Raw Gain Maximized near 490 MHz enlarge 254KB, 1152x703 8 490 MHz H-Pol 15-Turn Helical + Square Grid UHF SWR (200-ohms) = 1.4 across Entire Band enlarge 303KB, 1152x703 9 490 MHz H-Pol 15-Turn Helical + Square Grid UHF Impedance = 240 - 250 ohms enlarge 299KB, 1024x1024 10 490 MHz H-Pol 15-Turn Helical + Square Grid Azimuthal Pattern at 490 MHz Raw Gain = 4.0 to 6.3 dBi enlarge 276KB, 941x1024 11 490 MHz H-Pol 15-Turn Helical + Square Grid Elevation Gain Pattern Worst Case -23.6 dBi Null at Elev=20-deg enlarge 210KB, 659x1024 12 490 MHz H-Pol 15-Turn Helical + Square Grid Side View [1 Large Square = 12.5-inches] enlarge 151KB, 791x1024 13 490 MHz H-Pol 15-Turn Helical + Square Grid EVAL *.html Performance File incl. 4NEC2 File which includes Dimensions.
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