DBGH (Double Bay Gray Hoverman) with 28 Reflector RODs (3/8-in O.D.). Combo Hi-VHF & UHF Antenna Simulation Runs using 4nec2 for JUST the Ch9-10 Optimized Version. For alternative Ch7-8 and Ch11-13 Optimized Performance Summary & Dimensions, see last 4 images on this web page. Antenna Design and original EZNEC file posted by <300ohm> on 16Jan2009 to: http://www.digitalhome.ca/forum/showthread.php?t=99907
Slides 7-15 are UHF Band Performance. They illustrate the need to use BARE WIRE (vice Insulated) for UHF Band. Above Ch47 had both Raw Gain Loss and additional Net Gain Loss due to SWR degradation.
Slides 16-24 are Hi-VHF Performance. Insulation had only minor impact...and actually IMPROVED CH7. However, these detriments could appear in different forms in other designs...
Note poor F/B and F/R on all Hi-VHF except Ch9 & 10. Some Elements can be adjusted to reoptimize for either Ch7-8 or Ch11-13.
UPDATE 31Jan2009: Due to (inches vs meters) error in defining insulation thickness in 4nec2 file, updated all runs.
UPDATE 25Feb2019: Added nikiml EVAL Text File Summaries for Ch7-8, Ch9-10 and Ch11-13 alternative Versions.
Date(s): 31 Jan 2009 (UPDATE). Album by holl_ands. 1 - 31 of 31 Total. 15372 Visits.
enlarge 0KB, 594x1024 1 DBGH with 28 RODs (3/8-in O.D.) - 3D View
enlarge 0KB, 313x1024 2 DBGH with 28 RODs - Side View Small Box = 1 inch
enlarge 0KB, 518x1024 3 DBGH with 28 RODs - Front View Small Box = 1 inch
enlarge 8KB, 791x1024 4 4nec2 File: DBGH with 28 Reflector Rods No Insulation on Wires or Reflector Rods.
enlarge 9KB, 791x1024 5 4nec2 File: DBGH with 28 Reflector Rods Insulation on Vertical Zig-Zag Wires (only). No Insulation on Reflector Rods.
enlarge 10KB, 791x1024 6 4nec2 File: DBGH with 28 Reflector Rods Insulation on all AWG10 Wires. No Insulation on Reflector Rods.
enlarge 167KB, 1024x793 7 DBGH with 28 Reflector Rods No Insulation on Wires or Reflector Rods. 3D Total Gain Pattern at 590 MHz
enlarge 165KB, 1024x793 8 DBGH with 28 Reflector Rods No Insulation on Wires or Reflector Rods. 3D Horizontal Polarized Gain Pattern at 590 MHz
enlarge 153KB, 1024x793 9 DBGH with 28 Reflector Rods No Insulation on Wires or Reflector Rods. 3D Vertical Polarized Gain Pattern at 590 MHz
enlarge 0KB, 1024x819 10 300ohm's DBGH with 28 RODS - UHF Gain
All Wires and Reflector RODS are Bare.
Ch14-51 Center Freqs are 473-695 MHz Ch52-69 Center Freqs are 701-803 MHz
enlarge 0KB, 1024x819 22 300ohm's DBGH with 28 RODS - Hi-VHF Gain PVC Insulation on Vertical Zig-Zags (only).
Minimal effect on Raw Gain.
enlarge 0KB, 1024x819 23 300ohm's DBGH with 28 RODS - Hi-VHF SWR PVC Insulation on Vertical Zig-Zags (only).
Minimal SWR impact.
enlarge 0KB, 1024x819 24 300ohm's DBGH with 28 RODS - Hi-VHF Impedance PVC Insulation on Vertical Zig-Zags (only).
All Reflector RODS (3/8-in O.D.) are Bare.
enlarge 0KB, 1024x819 25 300ohm's DBGH with 28 RODS - Hi-VHF Gain PVC Insulation on all AWG10 wires.
Minimal effect on Raw Gain, although Ch7 IMPROVED.
enlarge 0KB, 1024x819 26 300ohm's DBGH with 28 RODS - Hi-VHF SWR PVC Insulation on all AWG10 wires.
Minimal SWR impact. Note SWR DECREASE at lowest frequencies.
enlarge 0KB, 1024x819 27 300ohm's DBGH with 28 RODS - Hi-VHF Impedance PVC Insulation on all AWG10 wires.
All Reflector RODS (3/8-in O.D.) are Bare.
enlarge 26KB, 791x1024 28 300ohm's DBGH with 28 RODS nikiml's EVAL Text Summary for Ch7-8: L1=31.5-in, L2=12.5-in
enlarge 26KB, 791x1024 29 300ohm's DBGH with 28 RODS nikiml's EVAL Text Summary for Ch9-10: L1=30.25-in, L2=11.5-in
enlarge 26KB, 791x1024 30 300ohm's DBGH with 28 RODS nikiml's EVAL Text Summary for Ch11-13: L1=28.0-in, L2=10.0-in
enlarge 247KB, 791x1024 31 300ohm's DBGH with 28 RODS - pdf Drawing Note L1 & L2 choices for optimum Gain on Ch7, 9 or 13 [Reflectors are yellow, NAROD's are red]