[TowerTalk] A Question of GAIN

[John Langdon]

I make it 4.6 dBd for the first one,  +3 dB for the second one, plus 3 dB more for doubling from 2 antennas to 4 => 10.6 dBd

This is borne out by my experience with a mixed stack of C3's and C4XL's at the heights you mention.  Going from 2 to 4 antennas seems to make more than 3 dB of difference but I think that is psychology not electromagnetic theory.  Likewise, adding another pair for 6 should only add 1.5 dB or so, but it seems to make more difference in operation than that.  

This is all difficult to judge on HF because arrival angle makes such a difference, and in fact is the real reason to have more antennas.  I have seen instances where the low pair is 10 to 20 dB better than all 6, and where using the upper pair and lower pair without the middle pair (giving pretty high take off angle) is better than any other combo.

The old W3AFM articles talk about the marginal cost of the next dB (at the risk of sounding like an economist) and IMHO, stacking is worth the effort, after you have done the "easier" stuff.

73 John N5CQ



-----Original Message-----
From:	Josh Logan [SMTP:jlogan@bewellnet.com]
Sent:	Sunday, October 18, 1998 5:17 PM
To:	towertalk@contesting.com
Subject:	[TowerTalk] A Question of GAIN


Assume a person built a 4 stack of C3 Force 12 multi band yagis

The C3 is given 4.6 dbd net gain for 20m

IF stacked at say 35ft, 65 ft, 95 ft and 125 ft
What would be resulting GAIN?   

I would guess around 4.6 + 3.0 + 3.0 + 3.0 = 13.6 dbd net gain

Is this reasonable??  What is a good spacing ?  30 ft  ?
assuming 20m performance is important.

Josh  N7XM        dreaming of Four Stack

--
FAQ on WWW:               http://www.contesting.com/towertalkfaq.html
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com
Search:                   http://www.contesting.com/km9p/search.htm



--
FAQ on WWW:               http://www.contesting.com/towertalkfaq.html
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com
Search:                   http://www.contesting.com/km9p/search.htm