Mapped Antenna Null/Reception per Band

[tweiss3]

My HF antenna currently consists of a MyAntennas 8010P (plus a 6M dipole). MyAntennas was very nice to provide analysis of their antenna using different configurations here with collaboration from KK4OBI. This is wonderful information, however, is there some application, either a download or online, that can take the information and show the null spaces throughout the a world map so I can see which states/countries I cannot get on which bands based on the orientation I have the antenna hung between trees. I'm looking for this information separate of true propagation predictions, because I'm looking for some general simplified information, with the knowledge if the band is closed its not going to matter, but I would like to know if there is a country that I won't reach no matter what.

Secondly, I could do this in AutoCAD via a world map by placing the plot and drawing a line from the center of the plot through the point that the plot crosses 0db (is that correct, or should I be looking at 1db) and create a null triangle for each band and null across the world, but a map large enough for the entire world will be a huge CAD file.

Thanks for any help.

 

[popnokick]

My experience with wire antennas such as the EFHW from MyAntennas, as well as Off-Center Fed Dipoles from various vendors and of various lengths... and also using trees as supports.. is that from a global propagation perspective you will NOT have "null spaces throughout the a world map so I can see which states/countries I cannot get on which bands based on the orientation I have the antenna hung between trees." Some parts of the world may be more difficult to reach than others but it's a matter of being in the right place at the right time to take advantage of the propagation path that has opened up. Some paths open fairly regularly and predictably; e.g. from my QTH to Australia and the Pacific on 40 meters pre-sunrise and just after sunrise. There are others that open much less frequently, e.g. India, Pakistan, and Indonesia. The types of antennas you and I have are generally omnidirectional... even when installed with the "broadside" of the wire facing east to west, or north to south. My wire antenna is installed running from a northern tree on my lot to a southern support tree. Conventional wisdom is that it should favor east - west propagation, right? Not true at all.... it is mostly omnidirectional. I can work Canada to my north and South America to my south whenever I feel like it.... I just have to be on the right band at the right time of day. I worked Ireland on 6 Meters with my OCFD a few weeks ago.

This is VERY different from a beam / Yagi antenna which DOES exhibit directionality.... which is what it is designed to do. But wire antennas of the type you ask about and I'm noting here are not highly directional.

So the question then becomes is how do you regularly assess your antenna(s) performance in various parts of the world on various bands? The best way I know is to use the FT8 / FT4 modes available with the WSJT-X application AND couple that with data from the pskreporter.com real-time signal strength mapping of your signal. You will see a global map display of every station that is hearing you, and exactly how strong you are in their location. Once you have logged a few hundred FT8 / FT4 QSOs you can also use the GridTracker app to provide historical plotting on a global map.