[VHFcontesting] Yagiphobia, Confusion and Infusion

[Marshall-K5QE]

Hello to everyone interested in the topic of stacked loops.....

I put up 4 stacked 6M loops at 120ft here at the QE contest station.  
They received every microvolt of noise from 5 counties and 2 parishes!!  
It was awful.  I eventually took them down. Then along comes someone 
that basically said, "You idiot!!!  You put the stacked loops with the 
bottom one at about 20ft so that they don't receive all the noise".  
Thanks for letting me know after I had gone through all the agony.

Stacked loops(probably just two of them) are a good antenna for local 
rag chews where stations are located in many different directions.  But 
for working long distances, there is nothing that will beat a good yagi 
array.  We have 4 stacked 2M loops at 135ft....and we never use them 
because our yagi arrays are so much better.  Yagis do not receive noise 
from everywhere....you get noise from the front and some noise off the 
back.  There is very little noise from the other directions.  For us, 
noise rejection is really a big deal.

Of course, you mileage may vary.....

73 Marshall K5QE


On 9/18/2013 9:33 AM, Tommy wrote:
> My modeling four stacked of 6m loops suggests comparable gain to a 5 element yogi in all directions with roughly the same takeoff angle with 10' spacing. What's wrong with that?
>
> Seems to me that the noise problem is there regardless of loop vs. yagi. The noise on 6 at our contest site is just plain horrible at times with the yagi so I doubt it could be much worse. That is a problem that Ned's to be resolved with the power company, nothing else will be as defective.
>
> OK, now I'll stand by for all the apocryphal stories about how your power monopoly is unresponsive or worse, but I can say that ours has been very responsive when we tell them where the source is located. Might be due to the lead engineer being a ham.
>
> I have the loops assembled and just have to finish building the mounts for the side of the tower. More as it happens...
>
> Regards,
>
> Tom Holmes, N8ZM
>
> Holmes RF Technologies, LLC
>
> 937-528-9345
>
>
> On Sep 17, 2013, at 22:35, Jack W6NF <vhfplus at gmail.com> wrote:
>
>> On 9/17/2013 9:10 PM, K8TB wrote:
>>> The main disadvantage of a 4 bay omni is lthat you will pick up any QRN located anywhere. But a 4 bay absolutely has gain on the horizon. A 4 bay would have the proverbial  6 Db of gain, minus splitter/feedline and connector losses. What the 4 bay does is squash the donut flatter, and out. My day job depends on this (radio broadcast engineer with 5 FM transmitter sites).
>>>     I plan to put up a 4 bay omni for six at my remote base site. Then I switch over to the very quiet Innovative beam.
>>> We all should look at more of these antennas, but, to obtain the full 3 Db gain per doubling, you need to space the bays a full wave length, which is 20 feet. So the 4 bay would be 60 feet, bay 1 to bay 4. You can get by with half-wave spacing, with less gain.
>>>
>>> Tom Bosscher K8TB
>> I have never considered a 4-bay for 6, Tom...I know they're way too big...but on 2-meters it is a reasonable structure.
>>
>> As to QRN susceptibility, I believe the predominant component of power line noise is vertically polarized, which gives the horizontal loop some immunity. I recognize that, as John, AA5FC, pointed out, there is no front-to-back or front-to-side rejection to help minimize QRN but the loop stack at least allows one to have modest gain in all directions to enhance the probability of actually hearing someone otherwise inaudible in the nulls of even a smaller yagi.
>>
>> I usually figure on 2.5db gain per doubling, which is probably a bit conservative.
>>
>> I am a retired radio/TV Chief Engineer with responsibility for an 8-bay Class C FM station or two over the years. That was "back in the day" when stations actually hired full-time engineers. :>)
>>
>> 73,
>>
>> -- 
>> Jack, W6NF/VE4
>> Shelley, K7MKL/VE4
>>
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