Modeling an Array for K5OF
K5OF plans to put up a station in NC. He wants two 20/15/10M antennas stacked in between two 40M antennas. The question: what's the best stacking height/distance.
To answer the questions, I followed the procedures outlined by N6BV, which are:
- Determine the statistical distribution for the take-off angles for your location to populated parts of the world.
- Use Microdem to develop a terrain plot.
- Use HFTA from the antenna handbook to vary the stacking distances to cover those angles calculated in the first step.
Since I was interested in how the data was actually gathered, I conducted some research and found the link to a tool written by OH6BG, which calculates the take off angles from VOACAP files.
Jari provided me with some valuable help and I was able to produce .prn files for K5OF's location. Since Ed is located on the coast, the Microdem plot was essentially flat and didn't come into play for his QTH. So my next step was to use models for the C31XR using 4nec2d. I was able to obtain the model from N2IC's page. http://www.kkn.net/~n2ic/c31xr/c31xr.htm
I also corresponded with WN9O for help with the models. He provided me with the .ant files. http://www.qsl.net/wn9o/
Elevation Angle Analysis Notes
The general flow:
- Create the VOACAP Input files
- Run VOACAP to produce the output files
- Run Elevation Analysis tool to produce the .prn files for HFTA
Use this command to generate the VOACAP output file. This assumes a standard install for VOACAP.
cd c:\itshfbc\bin_win hf_parse.exe quiet c:\itshfbc voacap FILE.INP FILE.OUT