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 holl_ands | Home > Gray-Hoverman Antennas > 
DBGH Hi-VHF & UHF Combo - 300ohm
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.
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DBGH with 28 RODs (3/8-in O.D.) - 3D View

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DBGH with 28 RODs - Side View
Small Box = 1 inch


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DBGH with 28 RODs - Front View
Small Box = 1 inch


Enlarge Rich Text Format Document 4
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RTF4
4nec2 File: DBGH with 28 Reflector Rods
No Insulation on Wires or Reflector Rods.


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RTF5
4nec2 File: DBGH with 28 Reflector Rods
Insulation on Vertical Zig-Zag Wires (only).
No Insulation on Reflector Rods.


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RTF6
4nec2 File: DBGH with 28 Reflector Rods
Insulation on all AWG10 Wires.
No Insulation on Reflector Rods.


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DBGH with 28 Reflector Rods
No Insulation on Wires or Reflector Rods.
3D Total Gain Pattern at 590 MHz


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DBGH with 28 Reflector Rods
No Insulation on Wires or Reflector Rods.
3D Horizontal Polarized Gain Pattern at 590 MHz


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DBGH with 28 Reflector Rods
No Insulation on Wires or Reflector Rods.
3D Vertical Polarized Gain Pattern at 590 MHz


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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


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300ohm's DBGH with 28 RODS - UHF SWR

All Wires and Reflector RODS are Bare.


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300ohm's DBGH with 28 RODS - UHF Impedance

All Wires and Reflector RODS are Bare.


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300ohm's DBGH with 28 RODS - UHF Gain
PVC Insulation on Vertical Zig-Zags (only).

Raw Gain decreases above Ch47.


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300ohm's DBGH with 28 RODS - UHF SWR
PVC Insulation on Vertical Zig-Zags (only).

Above Ch47, excessive SWR further degrades Net Gain.


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300ohm's DBGH with 28 RODS - UHF Impedance
PVC Insulation on Vertical Zig-Zags (only).
[45 mil thickness, 3.5 Dielectric Constant]

All Reflector RODS (3/8-in O.D.) are Bare.


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300ohm's DBGH with 28 RODS - UHF Gain
PVC Insulation on all AWG10 wires.

Raw Gain decreases above Ch47.
Low freq Gain dip due to Insulation on Feedline.


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300ohm's DBGH with 28 RODS - UHF SWR
PVC Insulation on all AWG10 wires.

Above Ch47, excessive SWR further degrades Net Gain.


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18
300ohm's DBGH with 28 RODS - UHF Impedance
PVC Insulation on all AWG10 wires.
[45 mil thickness, 3.5 Dielectric Constant]

All Reflector RODS (3/8-in O.D.) are Bare.


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300ohm's DBGH with 28 RODS - Hi-VHF Gain

All Bare Wire & Rods.


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300ohm's DBGH with 28 RODS - Hi-VHF SWR

All Bare Wire & Rods.


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300ohm's DBGH with 28 RODS - Hi-VHF Impedance

All Wires & Reflector RODS are Bare.


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300ohm's DBGH with 28 RODS - Hi-VHF Gain
PVC Insulation on Vertical Zig-Zags (only).

Minimal effect on Raw Gain.


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300ohm's DBGH with 28 RODS - Hi-VHF SWR
PVC Insulation on Vertical Zig-Zags (only).

Minimal SWR impact.


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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 photo 25
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300ohm's DBGH with 28 RODS - Hi-VHF Gain
PVC Insulation on all AWG10 wires.

Minimal effect on Raw Gain, although Ch7 IMPROVED.


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300ohm's DBGH with 28 RODS - Hi-VHF SWR
PVC Insulation on all AWG10 wires.

Minimal SWR impact.
Note SWR DECREASE at lowest frequencies.


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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 Microsoft Word Document 28
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DOC28
300ohm's DBGH with 28 RODS
nikiml's EVAL Text Summary for
Ch7-8: L1=31.5-in, L2=12.5-in


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DOC29
300ohm's DBGH with 28 RODS
nikiml's EVAL Text Summary for
Ch9-10: L1=30.25-in, L2=11.5-in


Enlarge Microsoft Word Document 30
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DOC30
300ohm's DBGH with 28 RODS
nikiml's EVAL Text Summary for
Ch11-13: L1=28.0-in, L2=10.0-in


Enlarge PDF 31
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PDF31
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]


 
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