One of the propagation tools I own is ProLab Pro – this is a professional tool that performs ray tracing through a version of the International Reference Ionosphere – in this case IRI-2007.  Unlike VOACAP, this model works well at 160m.  The tool is excellent despite limits with its plotting capabilities and consumers massive amounts of CPU time to do extensive coverage maps.

I have used this tool to model Dxpedition performance and have then compared the results against the logs of what was actually worked.  The results from log analysis show very strong correlation with the model output.

For my own amusement, I just ran an analysis for a specific circuit from Heard Island to my QTH in Woodside. The results are most sobering…

With the current solar and geomagnetic conditions from today, I modeled the gray line propagation (which is modeled quite well by Proplab Pro) at their sunset - using a quarter wave vertical antenna on a beach as the TX antenna with the 400 watt VK power limit, with a vertical monopole antenna as the receive side (-0.3 dBi gain over my ground) the predicted signal level is…

-118 dBm

Like most propagation predictions, this is a median value so sometime it might be better than this or (if you can say it with a straight face) sometimes worse.

Anyone who works VK0EK from the Bay Area should treat themselves to a very good bottle of Champagne – the Gods of the Ionosphere are probably never on our side from the West Coast but I fear their laughter may be the only thing we do hear relative to Heard on TopBand.

From working with over 40 Dxpeditions on antenna and propagation planning, I’ve learnt the predictions are a good yard stick – surprises (good and bad) still present themselves but the predictions are rarely totally wrong.

Working VK0EK on 160m from the Bay Area looks extraordinarily tough.

Stu K6TU