[TowerTalk] Fwd: Dbi vs DBd

[w2lu]

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 at centurytel.net>
To: "AD5VJ Bob" <rtnmi at sbcglobal.net>; ""'Tower Talk'"" 
<towertalk at 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 at sbcglobal.net>
> To: "'Roger (K8RI)'" <K8RI-on-TowerTalk at tm.net>; "'Tower Talk'"
> <towertalk at 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 at contesting.com
>>> [mailto:towertalk-bounces at 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.
>>>
>
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk