[TowerTalk] Reflector in the back of shunt tower for 160m

[VE6WZ_Steve]

Ignacy,

I did notice that you were planning for elevated radials.
Be aware that the gain and F/B of the array is very sensitive to parasitic loss.
Ground loss will quickly diminish the current in the parasitic and the gain will crash.
It’s easy to model this.  Just include a series resistance in the parasitic element and watch the gain and F/B drop.

Field measuring the gain with on air tests can be difficult.  With only 3 or 4 dB forward gain compared to the single vertical, it can be very hard to measure.  Even using RBN reports, QSB can easily mask this small change.
However, 3 dB is, well…..3dB and it's like doubling your TX power.  For the really weak QSOs, when your signal is just bubbling around the noise, that 3dB can make the QSO.

I recommend you read about my tuning method. It is not a trivial process to tune the parasitic to match the model.

73, de steve ve6wz

> On Jan 27, 2022, at 9:04 AM, Ignacy Misztal <no9e at arrl.net> wrote:
> 
> Steve,
> 
> Excellent work and sorry for missing it.
> 
> I was thinking about a quick design. Elevated radials, not 100 ground ones. T coming from top of tower on ropes. Also 30m spacing so SWR changes less compared to the 20m and can be handled without extra matching by a tuner. If 4.5 db becomes 3 db it is still OK. If it drops to 1 db, not worth the effort. Perhaps I will experiment for the upcoming CQ 160 contest and report.  
> 
> Ignacy, NO9E 
> 
> On Thu, Jan 27, 2022 at 10:43 AM VE6WZ_Steve <ve6wz at shaw.ca <mailto:ve6wz at shaw.ca>> wrote:
> Yes.
> I wrote this paper about it. I talk about about modelling, design, construction and about tuning the array: 
> https://drive.google.com/file/d/1eVklkZtlJW93JIJ9oDqbCyl-Jkik6YEX/view <https://drive.google.com/file/d/1eVklkZtlJW93JIJ9oDqbCyl-Jkik6YEX/view>
> 
> 73, de steve ve6wz
> 
>> On Jan 27, 2022, at 8:17 AM, Ignacy Misztal <no9e at arrl.net <mailto:no9e at arrl.net>> wrote:
>> 
>> I am trying to get some gain on 160m where currently I have a shunt fed
>> 100m tower. It works well but is not spectacular.
>> 
>> I modeled a reflector some 100 ft away from the tower. Either as inv L with
>> one elevated radial or T with two elevated counterpoises. EZNEC shows up to
>> 4 dB gain as a reflector and up to 3 dB as a director. Is this realistic?
>> Has anybody done anything like that?
>> 
>> Ignacy NO9E
>> _______________________________________________
>> 
>> 
>> 
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