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Author Topic: BTV Vertical - Efficiency question  (Read 1062 times)
N2LK
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Posts: 71




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« on: February 14, 2013, 03:10:22 AM »

I have a ground mounted Hustler BTV for many years over 50 radials in my small backyard.
For 80 M efficiency improvement I have had success with 2 methods:

1. 40 meter resonator with DX engineering Hot Rodz cap hat
2. Homebuilt 40M coax trap at the top with 19 ft. horizontal wire tied off to nearby low tree

My question is- any significant difference (i.e. say 4+% ) between either method?

Any thoughts appreciated
73
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K3VAT
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Posts: 701




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« Reply #1 on: February 14, 2013, 04:28:27 AM »

I have a ground mounted Hustler BTV for many years over 50 radials in my small backyard.
For 80 M efficiency improvement I have had success with 2 methods:

1. 40 meter resonator with DX engineering Hot Rodz cap hat
2. Homebuilt 40M coax trap at the top with 19 ft. horizontal wire tied off to nearby low tree

My question is- any significant difference (i.e. say 4+% ) between either method?

Any thoughts appreciated
73

Hello,
Not sure what you're asking.  If you've had the antenna up for that long and experimented with both methods for 80M operation, then I think that you would be the person to best answer the question.  How does each method work as far as your ability to work those stations that you want to?  How well does each system perform across the 80M band?  An antenna system could be "efficient" for a particular type of operation such as "working the ARRL SS contest" and poor for "working the South Sudan DXPedition".   Empirical results always have the last word.

Without actually doing various extensive tests on signal strength measurement, it would be next to impossible, IMHO, to obtain empirical results where one could be compared antenna efficiency that resulted in that small of a significant difference between the two methods.  It would also be difficult to model this comparison without thorough knowledge of your setup as antenna typology, soil condx, nearby structures all could have substantial impact on the outcome.

Top loading the vertical is the preferred method, which is what you are doing in both cases.  But there is an alternate method to the coax trap that is more efficient and that is the Unadilla trap.  See their website.

 73, Rich, K3VAT
« Last Edit: February 14, 2013, 04:40:10 AM by K3VAT » Logged
W5WSS
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Posts: 1652




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« Reply #2 on: February 15, 2013, 11:24:21 AM »

Hello, well the systems are different because one is held vertically and the other uses a horizontal section.

but

Making quantitative measurements incomparable.

We can qualify that the efficiencies of the two are similar but are not reasonably able to quantity them in the field where strength measurements are very useful.

The systems you are asking about roughly radiate as follows.

The horizontal wire will radiate an unknown amount broadside to it's axis.
While the vertical portion radiates a portion in the vertical plane about the semi circle.
Whether or not this is useful utility depends on the goals of the user.
It certainly will present useful radiation for HF sky wave use.
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