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By Ruth Belmonte, Stephen Fast, and Joseph Schuster, Remcom, Inc.

ABSTRACT

Today's military works in a complex electromagnetic arena. IED jammers and UGS systems are examples where propagation is very near to the ground, and the interaction of signals with the earth can unintentionally alter propagation. In these scenarios the direct and reflected waves tend to cancel one another, causing the surface wave component to be the dominant mode of propagation. This surface wave must be taken into account in order to correctly model propagation of radio waves in these cases. Many methods of studying propagation do not incorporate the effects of subterranean layers of different materials. This paper demonstrates that subterranean layers can greatly impact near earth propagation. Radio propagation predictions made by Norton, XFdtd®, and the moving window finite difference time domain (MWFDTD®) methods are used to analyze propagation for near-ground antennas over various types of layered media.

INTRODUCTION

The complex electromagnetic environment faced by today's military forces is a challenge to manage and accurately model. On one hand, the jammers used to disable improvised explosive devices (IEDs) can interfere with a wide range of tactical communication systems. On the other hand, signals from battlefield radio systems can render IED jammers ineffective. These systems, as well as unattended ground sensors (UGS) and other modern military applications, are employed near to the ground. This proximity to the earth greatly affects the propagation of the signal, and must be properly modeled when designing equipment and planning communication systems.

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•White Paper: A Comparison Of Near Earth Propagation Over Layered Media