Hi Guy,
I'm sure that it would indeed be less than 10 dBd. I was just
trying to put a number on it that it could never possibly exceed
no matter what that was 3 dB below his expectations. I have no
way to predict what he might actually get. Also I was not
addressing any possible benefits due to space diversity in the
elevation plane or increased capture area, etc.
73, Eric N7CL
>Reply-To: "Guy Olinger, K2AV" <k2av@qsl.net>
>From: "Guy Olinger, K2AV" <k2av@qsl.net>
>
>When stacks are modeled, you can see changes in element currents
>of the adjacent yagis, they are not independent of one
>another. These changes reduce the 3db intuitive figure to
>something over 2db, depending on the kind of antenna.
>
>If you look at the pattern of a single yagi in free space, there
>is a fair amount of radiation straight up and straight
>down. When the antennas are directly above one another, this
>vertical radiation "interferes" somewhat with the antenna above
>or below, resulting in the 2.x dB figure for stacking gain.
>
>If the yagi used as array elements is 4.6 dB gain, then 10 dB is
>really very good. Most likely 9.x, given harnesses, etc.
>
>73, Guy
>
>-----Original Message-----
>From: Eric Gustafson <n7cl@toontown.mmsi.com>
>To: towertalk@contesting.com <towertalk@contesting.com>
>
>>
>>
>>Josh,
>>
>>I think it would go more like:
>>
>>4.6 (for array element) + 3 (for the next one) + 3 (for the next
>> two) - (losses in harness and connectors)
>>
>>So I wouldn't expect more than 10 dBd net. And then only on the
>>band where the spacing was optimum.
>>
>>73, Eric N7CL
>>
>>
>>>From: "Josh Logan" <jlogan@bewellnet.com>
To: <towertalk@contesting.com>
>>>Date: Sun, 18 Oct 1998 16:17:14 -0600
>>>
>>>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
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