| Author |
Message |
    
Bob_p
Intermediate Member
Username: Bob_p
Post Number: 203
Registered: 7-2004
| | Posted on Wednesday, August 18, 2004 - 10:14 pm: | 
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I was just wondering if someone could explain db gain in very simple terms. |
Bruce
Senior Member
Username: Bruce
Post Number: 1486
Registered: 9-2003
| | Posted on Wednesday, August 18, 2004 - 11:28 pm: |
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YEP
3db= 2x power
6db= 4x power
9db= 8x power
10 = 10x power
13 = 20x power
16 = 40x power
19 = 80x power
20 =100x power
Now to get gain you have to compress the pattern a good example is if you want 9 db gain omidirectonal with a vertical you must compress the vertical lobe to about 10 deg to do this takes 8 1/2 wave antennas phased above each other LOOK AT A GOOD UHF BASE ANTENNA WITH 9DB GAIN it will have 8 PHASED ANTENNAS one on top of the other.
A 2 bay one 3db gain
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Bc910
Junior Member
Username: Bc910
Post Number: 45
Registered: 7-2004
| | Posted on Wednesday, August 18, 2004 - 11:52 pm: |
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DB gain is what happens when you eat too many doughnuts, FYI The term DB stands for "Dough Boy"
so when someone is talking about DB gain they are realy talking about a weight problem.
Oh no wait, thats right, I have no idea, what was I thinking?  ..........
Sorry, I don't know, but good question, I wanna know too!
BC |
Bob_p
Intermediate Member
Username: Bob_p
Post Number: 206
Registered: 7-2004
| | Posted on Thursday, August 19, 2004 - 1:21 am: |
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Thanks Bruce I knew it was a multiplication of the radios power but did not know what that was. I actually thought 3db gain was three times the radios power. So I guess on an I-Max 2000 with 3db gain would double the power of the radio it’s self. Thanks for guideline it really helps |
Bob_p
Intermediate Member
Username: Bob_p
Post Number: 208
Registered: 7-2004
| | Posted on Thursday, August 19, 2004 - 1:14 pm: |
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I have another questioin as a follow up. Does that mean that a 1/2 wave like the A-99 at about 2db would have 1.334X power then? |
Bruce
Senior Member
Username: Bruce
Post Number: 1488
Registered: 9-2003
| | Posted on Thursday, August 19, 2004 - 2:27 pm: |
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YEP
Over a isotropic antenna. REMEMBER unless the gain SAYS DBD its DBI. A ISOTROPIC antenna is one that radiates equaly well in every direction. |
Bob_p
Intermediate Member
Username: Bob_p
Post Number: 210
Registered: 7-2004
| | Posted on Thursday, August 19, 2004 - 3:38 pm: |
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Bruce.
Thanks alot. I really appreicate your willingness to share knowledge. |
Bruce
Senior Member
Username: Bruce
Post Number: 1489
Registered: 9-2003
| | Posted on Thursday, August 19, 2004 - 6:30 pm: |
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BOB thats what this forum is all about......
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