NVIS Advisor for EmComm
When the repeaters are down, AUXCOMM operators can still cover Atlantic County and the whole state on HF using NVIS (Near Vertical Incidence Skywave). You point a low antenna straight up, and the signal bounces off the ionosphere and comes back down over a circle a few hundred miles wide, with no skip zone and no towers needed. NVIS only works on frequencies below the ionosphere’s “critical frequency” (foF2), which changes all day long. This page reads live ionosonde measurements and tells you which band to use right now.
Recommended NVIS Antenna
A plain horizontal dipole (or inverted-V with a wide angle) mounted low: about 10 to 25 feet high on 80 m and 60 m, or 8 to 20 feet on 40 m. Low is the whole trick: it sends most of the signal straight up. A dipole at 50 feet or higher sends it out toward the horizon instead and you will skip right over the county. Put the same type of antenna up at both ends of the circuit, and on 40 m in the daytime a reflector wire on the ground under the dipole (about 5% longer) adds a few dB.
60 Meter Channels (great for NVIS)
| Channel | Center | USB dial setting |
|---|---|---|
| 1 | 5332.0 kHz | 5330.5 kHz |
| 2 | 5348.0 kHz | 5346.5 kHz |
| 3 | 5358.5 kHz | 5357.0 kHz |
| 4 | 5373.0 kHz | 5371.5 kHz |
| 5 | 5405.0 kHz | 5403.5 kHz |
General, Advanced and Extra class, USB voice, 100 watts ERP maximum. 60 m sits right between 80 m and 40 m, so it often works when 80 m is too weak and 40 m is skipping.
How it works: the ionosonde numbers come from the GIRO network through KC2G’s propagation service. The closest station with a fresh reading is used and scaled to South Jersey for the time of day, then compared with each band. GOOD means solid NVIS coverage, FAIR means it should work but may be weak or about to change, SKIPS means the frequency is above the critical frequency so the signal goes out to space or lands farther away, and ABSORBED means the daytime D-layer will soak up most of the signal. The “later today” forecast is an estimate based on the current reading. Always have a backup band ready. For long-distance bands, see the Best Band Right Now Advisor and the Emergency Comms Dashboard.