This paper discusses an analysis of Very High Frequency (203.25 MHz and 182.25 MHz) signal strength measurement variation over a sizeable hilly-forested region in the northern part of Aizawl, Mizoram. In this, we discussed the Line of Sight (LOS) analysis using Geographic Information System program and the area assessment within a specified region falling nearby the visible site, using a wedge-shaped area. We used this area to analyze zonal elevation data averaged over mixed rugged terrain features from Digital Elevation Model (DEMs) raster file. We also investigated the Normalized Difference Vegetation Index (NDVI) parameter within this same specified area. Our test analysis showed a decent relationship between signal strength variation with LOS classification and the mean elevation and proposed a simple regression loss model. However, we do not witness the association of signal variations with NDVI.

In this letter, we present a mathematical characterization of the Federal Communication Commission (FCC) F(50,50) curve for the Very High Frequency (VHF) and the Ultra High Frequency (UHF) band. The proposed empirical model is based on a novel step-wise curve fitting the FCC signal strength data. The F(50,50) model is intended for the TV broadcasting system and has been employed effectively in different literary works. Following this, we proposed a simple mathematical expression applicable to a 100 km distance with antenna height ranging from 30 to 300 m. The results showed that the proposed mathematical formulation agreed well with the F(50,50) curve data. Furthermore, the model presented is straightforward and can readily be implemented in VHF and UHF signal loss calculation requiring minimal input parameters.

Modeling forest propagation loss over a vast area is challenging, particularly for the hilly terrain regions where canopy obstacle depth varies with region. To consider such vegetation impact, we present a novel forest cover classification well-defined with the line-of-sight (LoS). Furthermore, we incorporated the mobile antenna site elevation angle, which showed significant influence within the target frequencies selected at 182.25 MHz 15 and 203.25 MHz (VHF Band III). We proposed a loss exponent dependent on the elevation angle and the vegetation-visibility classification, which is the basis of the model introduced in this paper. The resulting loss derived using this loss exponent showed a good agreement with the empirically derived loss variations. The proposed method offers an easy forest classification approximations with precise determination of signal variation over a wide-ranging forested area.