Just keep in mind that the commonly refered to dbd = dbi +2.15 commonly
assumes peak dbd in free space and dbi in free space. When you move to half
space, or above ground, things start getting sticky. How high above ground ?
How good is the ground ? What evelation and azmiuth angle ?
....................... But if your antenna peaks at 8 dbi in free space and
your competitor's antenna peaks at 12 dbi in free space, and you're both
running the same power, chances he'll beat you in a pileup.
----- Original Message -----
From: "Bill Aycock" <billaycock@centurytel.net>
To: "AD5VJ Bob" <rtnmi@sbcglobal.net>; ""'Tower Talk'""
<towertalk@contesting.com>
Sent: Tuesday, November 03, 2009 10:23 PM
Subject: Re: [TowerTalk] Fwd: Dbi vs DBd
> Bob-- In the design process, it does not matter, so long as the designer
> understands and uses a consistent set of methods and units. Only the
> designer must be satisfied.
> However, when you leave the design process and try to tell another about
> the
> results, the rules become different. Communication of the results must be
> such that the meanings are the same for the "teller" and the "Hearer".
> I clipped the post that was in yours to the most meaningful paragraphs.
> Good luck--Bill--W4BSG
>
> ----- Original Message -----
> From: "AD5VJ Bob" <rtnmi@sbcglobal.net>
> To: "'Roger (K8RI)'" <K8RI-on-TowerTalk@tm.net>; "'Tower Talk'"
> <towertalk@contesting.com>
> Sent: Tuesday, November 03, 2009 8:44 PM
> Subject: Re: [TowerTalk] Fwd: Dbi vs DBd
>
>
>> What about antenna design applications, do they give you a choice or one
>> or the other as a standard?
>>
>> Bob AD5VJ
>>
>>> -----Original Message-----
>>> From: towertalk-bounces@contesting.com
>>> [mailto:towertalk-bounces@contesting.com] On Behalf Of Roger (K8RI)
>>> Sent: Tuesday, November 03, 2009 7:36 PM
>>> To: Tower Talk
>>> Subject: Re: [TowerTalk] Fwd: Dbi vs DBd
>>>
>>> Nearly all of my engineering textbooks used dbi, but in the
>>> end, it makes not a bit of difference whether you use dbi or
>>> dbd in the practical world *IF* you know which is bing used
>>> AND you stick with the same units.
>>>
>>> db is a *ratio* whether it's db, dbi, or dbd. Some have a
>>> problem when the reference is different, but as long as the
>>> person reading or doing knows the difference it doesn't
>>> matter which reference is used.
>>>
>
>
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