RFscape

References

The literature, standards and data RFscape is built on. The first part lists what the program actually implements, with where it is used; the second part lists what was studied for the next developments and is not in the program yet.

Methods implemented

Propagation: Irregular Terrain Model (Longley-Rice)

  1. P. L. Rice, A. G. Longley, K. A. Norton, A. P. Barsis, Transmission Loss Predictions for Tropospheric Communication Circuits, NBS Technical Note 101, Volumes I and II, National Bureau of Standards, revised edition 1967. The theory behind ITM: diffraction, line-of-sight and troposcatter regions, variability.
  2. A. G. Longley, P. L. Rice, Prediction of Tropospheric Radio Transmission Loss over Irregular Terrain: A Computer Method - 1968, ESSA Technical Report ERL 79-ITS 67, July 1968. doi:10.70220/d3k87mv1 The Longley-Rice method; terrain irregularity, climates and ground constants offered in the tool.
  3. G. A. Hufford, A. G. Longley, W. A. Kissick, A Guide to the Use of the ITS Irregular Terrain Model in the Area Prediction Mode, NTIA Report 82-100, April 1982. Meaning of the parameters (variability modes, time, location and situation percentages) and their help notes.
  4. G. A. Hufford, The ITS Irregular Terrain Model, version 1.2.2: The Algorithm, NTIA Institute for Telecommunication Sciences. The equations, including the effective earth radius from the surface refractivity used for the profile drawing and the departure angles.
  5. G. A. Hufford, Memorandum on the changes from ITM version 1.2.1 (April 1979) to version 1.2.2 (September 1984), NTIA/ITS, 1985.
  6. NTIA Institute for Telecommunication Sciences, Irregular Terrain Model (ITM), reference implementation in C++, version 1.3 (functionally identical to the FORTRAN version 1.2.2), github.com/NTIA/itm. Compiled to WebAssembly without changes and called in point-to-point mode for every link and every point of a coverage map. RFscape adds only a thin wrapper (rfs_itm.cpp). US government work, acknowledged here as its licence asks.

Line-of-sight links

  1. Recommendation ITU-R P.530-19 (09/2025), Propagation data and prediction methods required for the design of terrestrial line-of-sight systems, International Telecommunication Union, Geneva. Surface reflection analysis (§ 6.1.2) and rain attenuation of a link exceeded for 0.01 % of the year (§ 2.4.1).
  2. Recommendation ITU-R P.525-5 (11/2024), Calculation of free-space attenuation, International Telecommunication Union, Geneva. Free-space loss and the conversion between received level and field strength in the exports.

Atmosphere: gases and rain

  1. Recommendation ITU-R P.676-13 (08/2022), Attenuation by atmospheric gases and related effects, International Telecommunication Union, Geneva. Specific attenuation of oxygen and water vapour, line by line (Annex 1), added to every path from 1 GHz: ITM does not include it. Checked against the reference implementation Py452 (identical values).
  2. Recommendation ITU-R P.838-3 (03/2005), Specific attenuation model for rain for use in prediction methods, International Telecommunication Union, Geneva. Coefficients k and α of the specific rain attenuation, for any frequency and polarisation. Checked against its Table 5.
  3. Recommendation ITU-R P.837, Characteristics of precipitation for propagation modelling, International Telecommunication Union, Geneva. Recommended source of the rain rate R0.01 that the user enters; its maps are not included in RFscape.

Geodesy

  1. T. Vincenty, Direct and inverse solutions of geodesics on the ellipsoid with application of nested equations, Survey Review 23 (176), 88-93, 1975. doi:10.1179/sre.1975.23.176.88 Distances, azimuths and the points of every path profile and coverage radial.
  2. National Imagery and Mapping Agency, Department of Defense World Geodetic System 1984, Technical Report TR8350.2, third edition, 2000. The WGS 84 ellipsoid used by the geodesy and the exports.

Terrain

  1. Airbus Defence and Space, Copernicus Digital Elevation Model Product Handbook, version 5.0, November 2022. Structure of the GLO-30 and GLO-90 tiles (sample grid, latitude bands, overviews) read by the terrain reader.
  2. Copernicus DEM GLO-30 and GLO-90, © DLR e.V. 2010-2014 and © Airbus Defence and Space GmbH 2014-2018 provided under COPERNICUS by the European Union and ESA; all rights reserved. Copernicus Digital Elevation Model (DEM) was accessed on 05/11/2026 from registry.opendata.aws/copernicus-dem.
  3. B. K. P. Horn, Hill shading and the reflectance map, Proceedings of the IEEE 69 (1), 14-47, 1981. doi:10.1109/PROC.1981.11918 Slope and aspect of the shaded relief drawn on the map.

Antennas

  1. C. A. Balanis, Antenna Theory: Analysis and Design, 4th edition, Wiley, 2016. Textbook results used for the vertical presets: half-wave dipole element factor and array factor of uniform collinear arrays.
  2. R. Coudé (VE2DBE), Radio Mobile, and I. D. Brown (G3TVU), Radio Mobile Handbook. The .ant antenna pattern format, so that existing pattern files can be loaded. No Radio Mobile code is used.

Amateur radio conventions

  1. IARU Region 1, Technical Recommendation R.1, 1981. S-meter scale: S9 = -93 dBm above 30 MHz and -73 dBm below, 6 dB per S-unit.
  2. IARU Region 1, Maidenhead Locator System, 1980. Six-character locators of the stations.

File formats

  1. Adobe Systems, TIFF Revision 6.0, 1992; Adobe Photoshop TIFF Technical Notes (Technical Note 3: floating point predictor), 2005. Reading the terrain tiles and writing the GeoTIFF exports.
  2. Open Geospatial Consortium, OGC GeoTIFF Standard 1.1 (19-008r4), 2019, and OGC KML 2.2 (07-147r2), 2008. Georeferencing of the GeoTIFF exports and the Google Earth KMZ.

Cable attenuation figures are typical values from the manufacturers' catalogues. Base map © OpenStreetMap contributors.

Studied for the next developments

Not used by the program yet. Each line says what it is meant for.

Other propagation models

  1. Recommendation ITU-R P.1812-8 (09/2025), A path-specific propagation prediction method for point-to-area terrestrial services in the frequency range 30 MHz to 6 000 MHz. A modern alternative to ITM for coverage maps.
  2. Recommendation ITU-R P.452-18 (10/2023), Prediction procedure for the evaluation of interference between stations on the surface of the Earth at frequencies above about 0.1 GHz. Interference between stations of a network.
  3. Recommendation ITU-R P.1546-6 (08/2019), Method for point-to-area predictions for terrestrial services in the frequency range 30 MHz to 4 000 MHz.
  4. Recommendation ITU-R P.2001-6 (09/2025), A general purpose wide-range terrestrial propagation model in the frequency range 30 MHz to 50 GHz.
  5. Recommendation ITU-R P.1411-13 (09/2025), Propagation data and prediction methods for the planning of short-range outdoor radiocommunication systems.
  6. eeveetza, Py1812, Py452 and Py2108, Python reference implementations of the ITU-R Recommendations with validation data, github.com/eeveetza. To validate future implementations of P.1812, P.452 and P.2108.

Diffraction

  1. Recommendation ITU-R P.526-16 (11/2025), Propagation by diffraction. A knife-edge cross-check of ITM when an obstacle stands very close to an antenna.
  2. N. DeMinco, P. M. McKenna, R. T. Johnk, A Comparative Analysis of Multiple Knife-Edge Diffraction Methods, NTIA Technical Report TR-26-580, October 2025.

Clutter, vegetation and land cover

  1. Recommendation ITU-R P.2108-1 (09/2021), Prediction of clutter loss.
  2. Recommendation ITU-R P.833-10 (09/2021), Attenuation in vegetation.
  3. ESA, WorldCover 10 m 2021 v200 Product User Manual, version 2.0, 2022. Land cover map for clutter and vegetation corrections.

Atmosphere at higher frequencies

  1. Recommendation ITU-R P.453-14 (08/2019), The radio refractive index: its formula and refractivity data. Surface refractivity maps instead of a fixed value.
  2. Recommendation ITU-R P.834-9 (12/2017), Effects of tropospheric refraction on radiowave propagation.
  3. Recommendation ITU-R P.372-18 (09/2026), Radio noise. Radio noise and refraction matter for the planning of microwave links; not modelled yet.

Geodesy and site selection

  1. C. F. F. Karney, Algorithms for geodesics, Journal of Geodesy 87, 43-55, 2013. doi:10.1007/s00190-012-0578-z A more robust geodesic solution than Vincenty's for very long paths.
  2. H. Haverkort, L. Toma, A Comparison of I/O-Efficient Algorithms for Visibility Computation on Massive Grid Terrains, arXiv:1810.01946, 2018.
  3. W. R. Franklin, S. V. G. de Magalhães, W. Li, Siting thousands of radio transmitter towers on terrains with billions of points, arXiv:2006.16783, 2020. Viewsheds and automatic choice of repeater sites.

Classic papers cited by the documents above

Not consulted directly: their methods reach RFscape through ITM and the ITU-R Recommendations.

  1. K. Bullington, Radio Propagation at Frequencies above 30 Megacycles, Proceedings of the IRE 35 (10), 1947. doi:10.1109/JRPROC.1947.232600
  2. J. Epstein, D. W. Peterson, An Experimental Study of Wave Propagation at 850 Mc, Proceedings of the IRE 41 (5), 1953. doi:10.1109/JRPROC.1953.274401
  3. E. K. Smith, S. Weintraub, The Constants in the Equation for Atmospheric Refractive Index at Radio Frequencies, Proceedings of the IRE 41 (8), 1953. doi:10.1109/JRPROC.1953.274297
  4. J. Deygout, Multiple Knife-Edge Diffraction of Microwaves, IEEE Transactions on Antennas and Propagation 14 (4), 1966. doi:10.1109/TAP.1966.1138719
  5. M. Hata, Empirical Formula for Propagation Loss in Land Mobile Radio Services, IEEE Transactions on Vehicular Technology 29 (3), 1980. doi:10.1109/T-VT.1980.23859
  6. L. E. Vogler, An Attenuation Function for Multiple Knife-Edge Diffraction, Radio Science 17 (6), 1982. doi:10.1029/RS017i006p01541