[TowerTalk] Takeoff angle
Bob Shohet, KQ2M
kq2m at kq2m.com
Sun Jul 23 14:24:10 EDT 2017
Several additional points to keep in mind:
1) Where in the mid-West are you? Southern Ohio has very different propagation than Northern Wisconsin. Your location will affect what parts of the world to which you have the best paths, especially during disturbed cndx when North-South paths predominate. Minnesota has a great path to JT1 and UA0 – from Southern Ohio not so much; but EU is generally much better from Southern Ohio than Minnesota.
2) What parts of the world do you want to work the most? JA has very different and lower angles of propagation than EU. If you want to work the US also then you want even higher angles.
3) What types of antennas do you plan to use? Different antennas will often have different angle lobes at the same height.
4) Do you plan to stack any antennas or just use one per band?
5) Effects of terrain on antenna wave angles for a given height can be enormous and VERY counterintuitive. And then it will vary again for a given antenna compared to another. And vary again if you are going to put up stacks.
6) All of this varies enormously as you progress from the top of the cycle to the bottom of the cycle. At the bottom of the cycle, your DX antennas all need to be higher up vs. the top of the cycle when low antennas often perform best - especially on the high bands.
My suggestion would be for you to first determine the height of your tower and the types of antennas that you want to use, then model them over your terrain and compare to the HFTA data for arrival wave angles at a given qth.
The BEST way to learn what DX can be worked at various points in the cycle from similar qth’s to yours, would be for you to access the CQWW DX SSB and CW logs
from the www.cqww.com websites. Study what is worked by the stations on each band from similar qth’s at various points in the sunspot cycle. Then look at the antennas that they used. That will give you a good indication of what can probably be worked from your qth. From there you can determine what parts of the world on which to focus our attention and what wave angles you want to concentrate on.
From: Chuck Dietz
Sent: Sunday, July 23, 2017 1:12 PM
To: Jeff Draughn ; towertalk at contesting.com
Subject: Re: [TowerTalk] Takeoff angle
Assuming you have picked the proper geographic area, the height of the bars
at the bottom under the curves represent the percentage of the time signals
from wherever you picked to your QTH come in at the angle listed under the
bar. This can lead to some surprising results and is fun to play with.
Much of what I thought was validated for my station, however, I moved my
fixed SE and SW antennas to cover angles that the higher antennas missed.
On Sun, Jul 23, 2017 at 11:41 AM Jeff Draughn <n0ost99 at gmail.com> wrote:
> I've been playing around with HFTA trying to figure out the best height/
> configuration for my antennas and it dawned on me I wasn't sure what the
> best take off angles are. I know low is better than high for DX, I'm
> assuming it's a range that I'm looking for.
> When looking at the plots what would be considered good take off angles
> for DX contests from the midwest.
> What is considered too high of an angle for DX?
> Jeff, N0OST
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