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[WT4W]

I've been playing around with EZNEC to get an idea of which antennas might work best within the constraints of my available space and antenna supports (i.e. trees).  I came across this link  http://home.scarlet.be/on9cvd/E-Opstralingshoek.htm   where it's indicated that desirable antenna takeoff angles are as high roughly 40 degrees for 80 meters down to approximately 7 degrees for 10 meters (those numbers from the 50% line on the first graph).  Of course this article stated that the desired path was 1500 km, which isn't all THAT far.

Can anyone point me to other articles or data discussing optimum takeoff angles per band, etc? 

[W1VT]

http://www.voacap.com/documents/N6BV_Visalia_2009.pdf
2009 Presentation by retired ARRL Antenna Book editor Dean Straw

Recent editions of the ARRL have the program HFTA that can be used to display the propagation path statistic data compiled by Dean.
Dean's work is described in chapter 4 of the 23rd edition of the ARRL Antenna Book.

I'd avoid using Microdem to obtain terrain data.  Instead, k6tu.com will send you terrain data as part of a free trial of his service.

Zak W1VT

[WT4W]

Interesting stuff. 

I'll have to dig out my Antenna Handbook and do some reading.

[KH6AQ]

W6ELProp (a free program) computes take-off-angles for each band. https://www.qsl.net/w6elprop/

I ran it a minute ago using solar-terrestrial conditions for today and a Georgia-to-England path. Here is what it reports for take-off-angles:

80 meters, 2-9 degrees
40 meters, 2-24 degrees
20 meters, 2-9 degrees
15 meters, 2 degrees

If W6ELProp is to be believed, the low frequency/high angle and high frequency/low angle rule-of-thumb is not always useful.

Using EZNEC I compare the gain of different antennas at a particular take-off-angle. I don't pay much attention to the angle of maximum gain.

Using W6ELP, click like so:

Predictions
On-screen
Input terminal A and B locations
OK
Show Prediction
Advanced
   You will now see Freq, Hop Configuration, and Angle

To go back click:
File
Back

[WT4W]

W6ELProp (a free program) computes take-off-angles for each band. https://www.qsl.net/w6elprop/

......... I don't pay much attention to the angle of maximum gain.

Good stuff, thanks.  And with where we're at with propagation right now it's pretty obvious that improving my antenna situation will do far more for me than eeking the last few watts out of an amplifier.

And yes, now that I've started playing around with EZNEC I can see perfectly why the angle of maximum gain isn't very useful.  In fact I fell prey to that when I chose to put up my quarter wave ground plane for 40 meters.  It has a much lower angle of max gain that a dipole  at a similar height (approx. 50 ft), but I see now that the dipole (or even an inverted V) will have a good bit more gain at that angle, and also cover a much broader range of takeoff angles.

Right now I'm trying to decide what will work best for me on 80 and 160 given my limitation of approximately 50 ft.

[K4DXG]

A classic explanation of some things to consider by Tom W8JI:

https://www.eham.net/articles/23758

[KH6AQ]

W6ELProp (a free program) computes take-off-angles for each band. https://www.qsl.net/w6elprop/

......... I don't pay much attention to the angle of maximum gain.

Good stuff, thanks.  And with where we're at with propagation right now it's pretty obvious that improving my antenna situation will do far more for me than eeking the last few watts out of an amplifier.

And yes, now that I've started playing around with EZNEC I can see perfectly why the angle of maximum gain isn't very useful.  In fact I fell prey to that when I chose to put up my quarter wave ground plane for 40 meters.  It has a much lower angle of max gain that a dipole  at a similar height (approx. 50 ft), but I see now that the dipole (or even an inverted V) will have a good bit more gain at that angle, and also cover a much broader range of takeoff angles.

Right now I'm trying to decide what will work best for me on 80 and 160 given my limitation of approximately 50 ft.

I recently installed an 80 meter inverted-L. It's 30' vertical and 35' horizontal over 32 radials having an average length of 35 ft. It was compared against a 100' inverted-vee at 35' on over a hundred A-B receive comparisons. The inverted-vee was better in almost every instance, which surprised me.

[W1VT]

If you are serious you really need to try both horizontal and vertical polarization, unless your circumstances limit  you to just one option.  Low band vertical polarization works really well for me, as I have unusually wet clay soil.  And I grow roses, so my soil has a ton of organic matter and fertilizer mixed into it.

Dipoles tend to have the strongest possible signals.  But you can often fit an Inverted-L into half the space of a dipole, since a resonant radiator is a just a quarter wavelength.

Sometimes DXing is just being there.   I just worked VP6R on 40SSB who was calling CQ because the band is open but not many get up  at 5:30 AM to work DX.

Zak W1VT