Near Vertical Incidence Skywave


Calculations require knowledge of the current F2 Critical Frequency and height. Ionograms containing these values are made available by the UMass Lowell. UK based users are most likely to find the data collected at RAF Fairford to be of most interest. Enter the Tx co-ordinates along with F2 critical frequency and the height of the F2 layer.


NB: Use negative values for South/West

Here are the optimum frequency and aerial details for a half wave dipole with a reflector wire mounted 0.15 wavelengths below the main wire.