Horizon hugging.

I was idly looking at the ITUHFPROP propagation prediction pages this morning, although I don't really know why, as the forecasts are often way out.

Still, I noticed that there is a 'Takeoff Angle' calculator that looked like it might be worth a look.

In essence, the software looks at the path, selectable between short or longpath between stations, and produces graphs predicting the most likely takeoff angle involved.

I think the page requires a bit of clarification, because it's not clear who's takeoff angle it is actually providing, though I assume it's that relevant to the transmitting site.

Also, ITUHFPROP is not very useful for lacking any vertical antenna options.  The alternative, PROPPY site is much better in this regard.

Here is the ITUHFPROP prediction for propagation between a middle-distance, run-of-the-mill path between Wales and Greece, showing how the angle changes during the day, though it never reaches very low angles:

Now look at the angle necessary for a Wales-Japan (short) path.  Note that the graphs do not have the same vertical scaling:

This is a path needing a constant takeoff angle of about 3.5 degrees.  To get a feel for what that looks like in reality, take a sea horizon and hold out two fingers horizontally together at arm's length.  That's roughly 3 degrees; it's a very low angle that most people cannot access.

For a Wales-Japan long path route, the necessary angle is even lower - just under 2 degrees. 

That's where a super-clear, super-ground location at the beach is such a wonderful place to play radio, and why a vertical antenna is a great help to achieve those low angles.

What stations await beyond?

A modelled (in this case, 7MHz) quarter wave vertical with seawater ground constants.  Peak (and good) gain in just the right place for long-haul DX!