Propagation Maps for 7 MHz

Using the VOACAP online program, I collected color-coded maps representing the predicted signal power (dB relative to 1 watt) centered on a designated transmitter site.  In the program this map is obtained from the SDBW button at the lower right corner of the main page.

I used the grid square location for W4UOA as the transmitter site and specified SSB mode, 500 W power and antenna at 33 ft (one of the limited menu selections).

The results are shown below for 1200, 1300 and 1400 UTC, encompassing the period of the RV Service net.  Below is the standard output from the program, for 1200 UTC -- covering the entire world. On the right side is a scale showing the relationship of color to the predicted received dBw signal level.

Since our area of interest for the RV Net is just the USA, I made a cropped version of each map. The results are below this one.

Click on image above for a full size view.

1200 UTC

Above is the cropped copy of the 1200 UTC map. The predicted low signal level within a few hundred miles of W4UOA is clearly seen and is consistent with the observed signal levels during the early part of the first hour of the Net.

1300 UTC

Above is the cropped version of the 1300 UTC map. The low signal (skip zone or doughnut hole) area is shrinking in size at the beginning of the second hour of the Net.

1400 UTC

Here is the 1400 UTC map, showing that good signal levels are now predicted closer to the W4UOA transmitter. This represents the end of the Net's second hour.

On a typical Thursday morning I am not able to copy W4UOA at 1300 UTC, but usually around 1330 UTC the signal comes up to a solid Q5 level. The distance from my station to W4UOA is 430 miles.

Many interesting reports and graphics are available from VOACAP, and I'm still getting acquainted with them. An excellent user guide for the online program is available at this web site. Another option for use is to download and install the program on your own computer. I may try that.

73,
John WA5MLF