Hanover Area Hamming Association

Hanover, Pennsylvania

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Propagation Movies

What is it trying to tell me?

What is this?

It is a map of the predicted propagation from Hanover to the rest of the world.

This map is very busy so let's figure out what we are interested in. For Field Day it is the United States and Canada. Everything we want is in centered in the top left quarter of the map. Find the red dot. That is our Field Day site. The Canadian and Mexican borders are shown. You can mentally fill in the rest. Also notice the yellow dot that moves from right to left. That is the sun. The sine wave like curve that follows it is the terminator. It is day on the side with the sun and night on the other side.

Look at the top enter of the title section. There is a number that keeps changing. That is the time that these predictions are valid. The movie covers the Field Day period. Field Day starts at "18 UTC" or 2:00 pm EDT and runs for 24 hours.

What are these colored blobs?

The color indicates the probability of successfully communicating over a particular path.

Propagation predictions are calculated for a specific path, on a specific date under specific conditions. For example: Hanover to Miami, Florida during the month of June 2017, using 100 watts and dipole antennas. Let's say that the program calculates an 80% probability at 8 pm EDT on the 40 meter band. It then colors the Miami area a light red color. It repeats these predictions for hundreds of paths and plots the colors on the map.

There is a scale on the right edge of the map that shows these probabilities for each color. Red is 100%, green is 50% and no color is 0%. What does this mean? An 80% probability means that for 24 days of the month this path will be usable under the conditions specified. The other six days it will not be usable. We will not know if Field Day is in the 24 day or the 6 day group until the contest actually starts. It doesn't say whether the signal will be weak or strong - only that you can be heard.

What do we do with this information?

We plan our stations and antennas.

The predictions show no 10 meter openings to the United States or Canada during Field Day. If we had an all band antenna we could easily take advantage of an unexpected opening. Otherwise, the time and effort to put up a yagi on a 35 foot mast would be better spend on making better antennas for the lower bands. That is an easy decision.

15 meters is a more difficult choice. There are a few hours of "iffy" openings to Florida, along the Gulf Coast and out to Southern California. This antenna should work well in the south through west directions at distances of 1,000 to 2,500 miles.

20, 40 and 80 meters all show good opening in all directions. The distance varies with frequency and time of day. We need good antennas for these bands.


I can watch these pretty colors dance around the screen for hours. It is like mindlessly watching a lava lamp. Although pleasing there no expectation of learning anything meaningful. If you can tear yourself away from the lava lamp obsession there is a goldmine of information here for some future operation. It can help you select bands, antennas and time of day to operate.

This was written to go with movies for the Field Day 2017. The ideas work anytime and anywhere. There are other formats for these prediction but this works good for the big picture.

The movies were produced by VOACAP Online at "http://www.voacap.com/". The individual maps were then combined into an animated gif.

See what we did in

previous Field Days

Field Day 2017

Will be June 24-25, 2017.