Near‐Ground Propagation Mechanisms in Wireless Communications

Abstract

In this chapter, we reexamine the solution of the century‐old Sommerfeld problem of a vertical or horizontal elementary Hertzian dipole antenna radiating over a material half‐space. This classical problem is still relevant to many modern applications, including geophysical prospecting, detection of unexploded ordnance, near‐ground sensors, on‐body networks, surface radar, and cellular wireless communications. To gain more insight into the near‐ground wireless propagation mechanisms, we derive the asymptotic field expressions by using the modified saddle‐point integration method, paying particular attention to the so‐called Norton surface wave and its significance in the total field of the dipole. We also extend the theory to include the effect of a thin, low‐loss overlayer. We illustrate and validate the theoretical developments by numerical results involving on‐surface and elevated transmitter–receiver configurations and different lower half‐space media, including seawater and urban ground, with emphasis on modern high‐frequency applications, where the media losses are relatively small. We also include a brief review of the history of the Sommerfeld half‐space problem with references to the most pertinent literature.