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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 Flat-Swept SBGH OMNI + TOP-HAT 490-MHz Flat-Swept SBGH (Single-Bay Grey-Hoverman), Horizontally-Polarized OMNI-Directional Antenna with 36-in Radius "Top-Hat" [to improve Look-Down Angle, i.e. Negative Elevation Pattern Gain] was analyzed using 4nec2. Min Gain = 7.1 dBi, Max Gain = 9.0 dBi.  Although this H-Pol. Antenna doesn't provide TRUE OMNI Azimuthal Pattern (equal Gain every direction), it DOES provide a MINIMUM Gain of 7.1 dBi or MORE on ALL Azimuths.  It is well matched to a Characteristic Impedance of 200-ohms, requiring the use of a 4:1 Balun (usually Coax type) to match 50-ohm Load with an SWR of less than 1.5:1, which is well within a typical Transmitter Limit of 2:1. Although specifically designed for an 8-MHz bandwidth DVB-T Ch23 Micro-Transmitter, the dimensions can be Rescaled to any desired Center Frequency by Fraction F = New Freq / 490 MHz [Smaller for Higher Freqs]. Date(s): 27 Feb 2016. Album by holl_ands. 1 - 14 of 14 Total. 2923 Visits.
enlarge 90KB, 1020x1024 1 490 MHz Flat-Swept SBGH OMNI + TOP-HAT 3D View enlarge 216KB, 904x1024 2 490 MHz Flat-Swept SBGH OMNI + TOP-HAT Front View [1 Large Square = 12.5-inches] 36-in Radius Top-Hat is 45-in Above Origin (Center of Antenna) enlarge 438KB, 1011x1024 3 490 MHz Flat-Swept SBGH OMNI + TOP-HAT Top View [1 Large Square = 12.5-inches] enlarge 107KB, 1152x415 4 490 MHz Flat-Swept SBGH OMNI + TOP-HAT Raw Gain = 9.0 to 9.2 dBi enlarge 223KB, 1152x703 5 490 MHz Flat-Swept SBGH OMNI + TOP-HAT UHF SWR Min = 1.4 at 490 MHz enlarge 235KB, 1152x703 6 490 MHz Flat-Swept SBGH OMNI + TOP-HAT UHF Impedance = 240 to 250-ohms near 490 MHz enlarge 308KB, 1024x1024 7 490 MHz Flat-Swept SBGH OMNI + TOP-HAT Azimuthal Pattern = 7.1 to 9.0 at 490 MHz enlarge 300KB, 1024x1024 8 490 MHz Flat-Swept SBGH OMNI + TOP-HAT Elevation Pattern at 490 MHz Moderate increase in Look Down Angle Gain But Deep Nulls are still Present enlarge 211KB, 904x1024 9 490 MHz Flat-Swept SBGH OMNI + TOP-HAT Side View [1 Large Square = 12.5-inches] enlarge 250KB, 791x1024 10 490 MHz Flat-Swept SBGH OMNI + TOP-HAT 4nec2 File includes Summary of Dimensions enlarge 26KB, 791x1024 11 490 MHz Flat-Swept SBGH OMNI + TOP-HAT EVAL Summary of Performance Text File enlarge 181KB, 791x1024 12 490 MHz Flat-Swept SBGH OMNI + TOP-HAT EVAL *.html Performance Summary enlarge 169KB, 768x1024 13 490 MHz Flat-Swept SBGH OMNI FLAT View [1 large square = 5-inches] enlarge 133KB, 768x1024 14 490 MHz Flat-Swept SBGH OMNI Top View [1 large square = 1.25-inches]
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