EM propagation explorer

Not BUILDER
Click the map to place a transmitter
Coverage mode: from one transmitter, how far does the signal reach in every direction?
Legend
TX (transmitter)
RX (receiver)

About this project

Hey—we're Sean and Derek. This is Not BUILDER.

Radio and radar don't propagate over a flat, standard atmosphere — they bend with whatever the troposphere is actually doing today: evaporation ducts over warm seas, elevated ducts under subsidence inversions, surface-based ducts that trap a signal and carry it far beyond the horizon, or superrefraction that just as often opens a radar hole. This site runs a real parabolic-equation propagation model, in your browser, against today's GFS atmosphere, so you can click a point on the map and actually see it: coverage, ducting, detection and intercept ranges, and a one-page Tactical Decision Aid you can print.

Built to teach, real enough to plan a lesson around

Every cross-section here is computed from the same NOAA GFS fields an operational tool would use, run through an open split-step parabolic-equation solver — not a canned demo. That keeps the physics honest. But this is a teaching aid, full stop: system parameters are unclassified open-source ballparks, and for anything operational you go to your command's authoritative sources.

Creators

CREATORS

LT Sean Egan, PhD & AG1 Derek Conklin
United States Navy · A partnership building learning tools for our METOC, space, cyber, and cryptologic colleagues.
sean@theinformed.org

Data sources

Atmosphere: NOAA GFS 0.25° via NOMADS. Basemap & borders: Natural Earth (public domain). Anomaly writeups: a deterministic detector, optionally narrated by a local language model and checked against the detector's own numbers — never the other way around.

Built in the spirit of NRL/SPAWAR-class propagation TDA tools (the BUILDER/AREPS heritage), and anchored to Wang et al., “Beyond-line-of-sight physical-layer chaos communication based on troposcatter,” Opt. Express 34(3):5169 (2026).

Independent educational project, built by us on our own time. The views expressed here are ours alone and do not reflect the official policy or position of the U.S. Navy, the Department of War / Department of Defense, or the U.S. Government, nor do we represent them. This site is intended for learning, not operations — not for operational decisions; use it at your own risk. No NRL or BUILDER/AREPS branding, endorsement, or affiliation is implied. Not a forecast, warning, or substitute for official guidance.

Why is it like this?

—

See where the signal actually goes.

A real propagation model, run against today's atmosphere, right in your browser.

Range–height cross-section

Move the cursor over the plot to read range · height · loss.

Colour shows the coverage margin (or Pd in radar Pd mode). Hover a chip to light up its region; click to pin. Press Esc or × to close.