What use is an F-call?

I recently spent some time talking about the Grey Line, about the way it moves around and how it will help you make contacts along its path.

If you recall, the direction of the Grey Line changes throughout the year. As the tilt of the earth affects the direction of the sun on your head, it also affects the shadow line that's drawn across the planet as sun-set and sun-rise occur at your QTH.

Of course, you already know this. We experience this change as our seasons.

So, if the Grey Line changes direction, the obvious question is, "Which way should you point your antenna?"

If you are using a vertical, there isn't much pointing going on, but if you have anything that is rotating, even a mobile station qualifies, there is benefit in actually aligning yourself with the Grey Line.

Of course you can look online and see a lovely Grey Line map and use that, but that does require that you have access to the Internet, or a phone with an App or some other technology.

But you don't really have to get that technical at all. The antenna you're using has a beam-width that is going to be several degrees wide and local environmental factors are going to impact on your experience, so, here's some figuring.

At the equinox, the Grey Line runs North - South, that is, twice a year around 20 March and 22 September. For our quick and dirty calculation, March and September is more than accurate enough.

At summer and winter solstice, 21 December and 21 June, the Grey Line runs at the maximum angle, the tilt of the earth, 23.5 degrees.

So, every quarter of the year, the Grey Line moves about 23 degrees, call it 21 degrees. So every month the Grey Line moves by about 7 degrees.

This is about equal to the width of a man's fist held at arm's length. (104mm)

So in December, you'll see the Grey Line running at about a bearing of 21 degrees, in January, about 14 degrees, in February about 7, in March about 0, that is North, and so on.

Now the only tricky part is, which way do you go around 0 degrees? Is February 7 degrees east, or 7 degrees west of North?

It depends on whether you're north or south of the equator. Here in VK, February is East, April is West, August is East, October is West. To remember that, think that the Grey Line is a FEAST. February is East and August is East.

Have fun working the Grey Line.

I'm Onno VK6FLAB