Average field attenuation in the nonregular impedance street waveguide

The propagation of electromagnetic (EM) waves in a city with a regularly planned building as a model of a straight street with buildings lining its sides is investigated. The street is considered as a planar two-dimensional (2-D) multislit waveguide with Poisson distributed screens (building walls) and slits (gaps between buildings). The electrical properties of the buildings' walls are taken into account by introducing the electrical impedance as a function of their surface permittivity and conductivity. The average field from the vertical electric dipole placed inside the street lower than rooftop level in the conditions of line-of-sight is investigated using Green's function formalism and real boundary conditions on the building walls. Evaluations show that the total field inside the waveguide can be presented as a superposition of a continuous spectral propagation component, which does not exist in the ideal unbroken waveguide, and a discrete spectral component, which describes the exponential attenuation of reflected and diffracted waves at distances of up to 2-3 km depending on the width of street. The presented model and evaluated formulas are in a good agreement with experimental data of ultrahigh-frequency (UHF)/L-band wave propagation in urban areas with a crossing-street plan.