EMPIRE Suite of Propagation Models
The Electromagnetic Propagation Integrated Resource Environment (EMPIRE) is a suite of government and commercial codes used to predict electromagnetic field propagation over a wide range of conditions, environments, and frequencies. It is designed as a plug-in library, and is used as the electromagnetic calculation engine by a number of government Tactical Decision Aids (TDAs). It is developed and maintained by Remcom under primary sponsorship of the USAF 453 Electronic Warfare Squadron (EWS), DOD program manager for EMPIRE, and the Naval Research Laboratory (NRL).
The key to EMPIRE’s success is that it provides a single uniform interface to a broad suite of codes, allowing tools to seamlessly switch between the codes as necessary to cover a range of potential applications and levels of fidelity. Standard data formats and a variety of built-in databases for environmental and climatology data further increase capabilities and ease of use. Figure 1 provides an overall architecture diagram. Through its XML or C++ APIs, tool designers can develop a single set of calls to specify inputs, execute simulations, and obtain outputs from any of the underlying models. Since its inception over a decade ago, EMPIRE has enjoyed use by a large user community in many other TDAs, resulting in many years of use and testing of the models by EMPIRE’s developers and users.
Models in the EMPIRE Suite
The base suite includes several government codes, supporting land, sea, and littoral environments; handling complex terrain and atmospheric conditions; and covering frequencies between 100 kHz and 300 GHz:
- Advanced Propagation Model (APM)
- Variable Terrain Radio Parabolic Equation (VTRPE) Model
- Terrain Integrated Rough Earth Model (TIREM)
- ITS Low-Frequency/Medium Frequency (LFMF) Groundwave & Skywave Models
- Millimeter Wave Model Propagation Model (MMWave)
- Irregular Terrain Model (ITM)
- Voice of America Coverage Analysis Program (VOACAP) HF Skywave Model
- Damboldt HF Skywave Model
- Hata and COST-Hata Empirical Urban Models
Option to Plug in Remcom Commercially-Licensed Models
At the request of some customers, Remcom has also added the capability to optionally plug in and access several models in our Wireless InSite and Wireless InSite Real Time tool suites from within EMPIRE, adding options for high-fidelity or high-speed urban modeling as well as high-fidelity modeling of fields over rough terrain:
- Remcom’s Wireless InSite Urban and Outdoor ray-trace models
- Remcom’s Moving Window FDTD model
- Remcom’s Wireless InSite Urban Real Time models
Uniform Interface to a Vast Array of EM Propagation Modeling Capabilities
Through its combined modeling capabilities, EMPIRE provides a vast capability to model the electromagnetic environment in a variety of physical and environmental conditions. Figure 2 shows an example of calculated propagation loss from ship-to-shore for a sample littoral scenario, with significant impacts from the terrain and atmosphere along the boundary, including shadowing and ducting. This demonstrates a small sample of the capabilities that EMPIRE can provide to any TDA that uses it for its EM calculations.