 symbolic representation of a propagation scenario over an irregular terrain. UTD-PO and FKE Models for Path Loss Prediction for such a terrain environment. Finally in Section V the work presented in the paper is concluded. 6.1.1 PROPAGATION ENVIRONMENT Figure 6.1 shows the schematic representation of a transmitter T of height h which is propagating spherical waves to a receiving point or moving mobile unit R of height hrx over an irregular terrain. There is a series of obstacles of uneven height (namely, h1, h2, h, hn) and spacing (namely, W1, W2, W3, ..., Wn' W(n+1)) between them. This series of obstacles are approximated as knife edge obstacles in which the only con- tribution to path loss is due to over-rooftop knife edge diffraction. In this, a spherical wave impinges on the rooftop of a knife edge obstacle at some angle of incidence when propagating from transmitter T. In Figure 6.1, an angle a1 represents the angle of incidence for obstacle 1 for a wave propagating from the transmitter. Similarly different obstacles of uneven height and spacing have their different angles of inci- dence which are used for the computation of path loss due to multiple over-rooftop diffraction. 6.2 PROPOSED ANALYSIS The proposed comparative study is done for path loss analysis for radio wave propagation over the irregular terrain scenario as shown in Figure 6.1. The path loss is predicted for the case when the receiver R or mobile unit is moving away from the transmitter T over a terrain having obstacles or hills of uneven height and spacing. For the prediction of path loss using the uniform theory of diffraction- physical optics UTD-PO and Fresnel-Kirchhoff knife edge diffraction theory FKE is applied. First, we calculate the path loss over an irregular terrain using a UTD-PO approach. It is a high-frequency electromagnetic field approximation approach which is used to determine the effect of radio propagation mechanism, for example, diffraction, inter- ference, polarization, and SO forth, for which other ray tracing approac