This code repository contains an the NTIA/ITS implementation of the Low Frequency / Medium Frequency (LF/MF) Propagation Model. LF/MF predicts basic transmission loss in the frequency range 0.01 - 30 MHz for propagation paths over a smooth Earth and antenna heights less than 50 meters.
| Variable | Type | Units | Limits | Description |
|---|---|---|---|---|
h_tx__meter |
double | meter | 0 <= h_tx__meter <= 50 |
Height of the transmitter |
h_rx__meter |
double | meter | 0 <= h_rx__meter <= 50 |
Height of the receiver |
f__mhz |
double | MHz | 0.01 <= f__mhz <= 30 |
Frequency |
P_tx__watt |
double | Watt | 0 < P_tx__watt |
Transmitter power |
N_s |
double | N-Units | 250 <= N_s <= 400 |
Surface refractivity |
d__km |
double | km | 0 < d__km |
Path distance |
epsilon |
double | 1 <= epsilon |
Relative permittivity | |
sigma |
double | S/m | 0 < sigma |
Conductivity |
pol |
int | Polarization
|
Outputs to LFMF are contained within a defined Result structure.
| Variable | Type | Units | Description |
|---|---|---|---|
A_btl__db |
double | dB | Basic transmission loss |
E_dBuVm |
double | dB(uV/m) | Electrice field strength |
P_rx__dbm |
double | dBm | Received power |
method |
int | Solution method
|
Possible return codes, including the corresponding defined constant name as defined in LFMF.h:
| Value | Const Name | Description |
|---|---|---|
| 0 | SUCCESS |
Successful execution |
| 1000 | ERROR__TX_TERMINAL_HEIGHT |
TX terminal height is out of range |
| 1001 | ERROR__RX_TERMINAL_HEIGHT |
RX terminal height is out of range |
| 1002 | ERROR__FREQUENCY |
Frequency is out of range |
| 1003 | ERROR__TX_POWER |
Transmit power is out of range |
| 1004 | ERROR__SURFACE_REFRACTIVITY |
Surface refractivity is out of range |
| 1005 | ERROR__PATH_DISTANCE |
Path distance is out of range |
| 1006 | ERROR__EPSILON |
Epsilon is out of range |
| 1007 | ERROR__SIGMA |
Sigma is out of range |
| 1008 | ERROR__POLARIZATION |
Invalid value for polarization |
A set of example inputs and outputs are provided for testing purposes. This is not a comprehensive validation test set. The test set can be found in LFMF_Examples.csv.
- In general, variables follow the naming convention in which a single underscore denotes a subscript (pseudo-LaTeX format), where a double underscore is followed by the units, i.e. h_tx__meter.
- Variables are named to match their corresponding mathematical variables from their publication text.
- Wherever possible, equation numbers are provided.
The software is designed to be built into a DLL (or corresponding library for non-Windows systems). The source code can be built for any OS that supports the standard C++ libraries. A Visual Studio 2022 project file is provided for Windows users to support the build process and configuration.
The .NET support of LFMF consists of a simple pass-through wrapper around the native DLL. It is compiled to target .NET Framework 4.8.1. Distribution and updates are provided through the published NuGet package.
- Bremmer, H. "Terrestrial Radio Waves" Elsevier, 1949.
- DeMinco, N. "Medium Frequency Propagation Prediction Techniques and Antenna Modeling for Intelligent Transportation Systems (ITS) Broadcast Applications", NTIA Report 99-368, August 1999
- DeMinco, N. "Ground-wave Analysis Model For MF Broadcast System", NTIA Report 86-203, September 1986
- Sommerfeld, A. "The propagation of waves in wireless telegraphy", Ann. Phys., 1909, 28, p.665
- Wait, J. "Radiation From a Vertical Antenna Over a Curved Stratified Ground", Journal of Research of the National Bureau of Standards. Vol 56, No. 4, April 1956. Research Paper 2671
For questions, contact Nick DeMinco, NDeminco@ntia.gov