Clear-Air Radioclimatological Modeling for Terrestrial Line of Sight Links in Southern Africa Odedina P.K. Aug , 2010 178
In figures 4.37 (a) and (b), the path loss is plotted against the coverage range or distance for the summer months of February in both Durban and Botswana. On the other hand in figures 4.38 (a) and (b), path loss is plotted against range for the winter months of August in both Durban and Botswana.
Several deductions can be made from these figures. It will be noticed that all the plot figures 4.35 – 4.38 show a progressive increase of path loss as the coverage range or distance increases, this is expected since theoretically more signal is lost as the propagation distance increases. The way each plot increases in path loss with distance is very unique to each location and season as can be seen from figures 4.35 – 4.38.
The remaining plots (Figure 4.37 – 4.38) corroborate most of our discussions in the preceding paragraphs. This is a plot of path loss versus range graphs and as could be seen from the plots, all the plots conspicuously show a gradual increase of the path loss with increasing range as expected.
However, it should be noted that in all the plots, the two heights (10 m and 20 m a.g.l) selected in these plots coincide for some range distance before the difference becomes obvious after this range.
The reason for this will be study further in future refinement of the model.
4.9 Second Modified Parabolic Equation (MPE2) (Takes into account the
Clear-Air Radioclimatological Modeling for Terrestrial Line of Sight Links in Southern Africa Odedina P.K. Aug , 2010 179
for different seasons and for the two locations being studied. The remaining task of the solution is resolved by the M-File MATLAB software code developed to implement the solution.
The path loss plots against height and range generated after this second modification for Durban and Botswana, in the seasonal months of February (summer) and August (winter) are shown in figures 4.39 – 4.42. These results are then discussed below the plots as we did earlier.
The coverage diagram looks alike for all type of modifications of parabolic equation. It was therefore not included in the next set of plots. Similar trend to previous discussion was observed for the second modification, there is a little difference in the results though as discussed in the paragraphs that follow.
Figure 4.39(a) Path Loss against Height at 19.5 GHz for MPE2 February 2004 Durban
Figure 4.39(b) Path Loss against Height at 19.5 GHz for MPE2 February 1996 Botswana
Clear-Air Radioclimatological Modeling for Terrestrial Line of Sight Links in Southern Africa Odedina P.K. Aug , 2010 180 Figure 4.40 (a) Path Loss against Height at 19.5 GHz for
MPE2 August 2004 Durban
Figure 4.40(b) Path Loss against Height at 19.5 GHz for MPE2 August 1996 Botswana
Figure 4.41(a) Path Loss against Range at 19.5 GHz for MPE2 February 2004 Durban
Figure 4.41(b) Path Loss against Range at 19.5 GHz for MPE2 February 1996 Botswana
Clear-Air Radioclimatological Modeling for Terrestrial Line of Sight Links in Southern Africa Odedina P.K. Aug , 2010 181 Figure 4.42(a) Path Loss against Range at 19.5 GHz
for MPE2 August 2004 Durban
Figure 4.42(b) Path Loss against Range at 19.5 GHz for MPE2 August 1996 Botswana
The path loss versus height is plotted in figures 4.39 – 4.40 for the seasonal months of February (summer) and August (winter) in Durban and Botswana. On the other hand, figures 4.41 – 4.42 show the plots of path loss versus range for the seasonal months of February (summer) and August (winter) in both Durban and Botswana. At a height level of 10 m a.g.l. and coverage range of 10 km Durban recorded a path loss value of 2.8 dB while Botswana has a path loss value of 2.6 dB in the summer months of February (see Figure 4.39 (a) and (b)).
Moving to a higher height level of 20 m a.g.l at the same coverage distance of 10 km, Durban recorded a path loss value of 3.05 dB while Botswana on the other hand has a path loss value of 2.9 dB for the summer months of February (see Figure4.39 (a) and (b)). At a longer range of 20 km, and height level of 10 m a.g.l., the result is as follows: Durban recorded a path loss value of 5.8 dB in the summer month of February while Botswana recorded a path loss value of 5.6 dB (see Figure 4.41 (a) and (b)). On the other hand at the same coverage range of 20km and a higher height level of 20 m a.g.l. Durban recorded a path loss value of 6.7dB in the summer month of February (obtained by extrapolation of Figure 4.41(a)) while Botswana recorded a path loss value of 6 dB in the summer month of February (see Figure 4.41(b)).
Clear-Air Radioclimatological Modeling for Terrestrial Line of Sight Links in Southern Africa Odedina P.K. Aug , 2010 182
The analysis for the winter months of August shows similar trend, for instance at a height level of 10 m a.g.l and a coverage range of 10 km in the winter months of August the result is as follows: Durban has a path loss value of 2.7 dB while Botswana has a path loss value of 2.6 dB (see Figure 4.40 (a) and (b)). Keeping the coverage range constant at 10 km and moving to a higher height level of 20 m a.g.l., Durban has a path loss value of 2.98 dB while Botswana at this new height level has a path loss value of 2.8 dB (see Figure 4.40 (a) and (b)).
In this same winter’s month of August at a longer coverage range of 20 km and a height level of 10 m a.g.l. the result is as follows: Durban has a path loss value of 5.7 dB while Botswana has a path loss value of 5.5 dB (see Figure 4.42 (a) and (b)). If we move to a higher altitude level of 20 m a.g.l. at the same coverage range of 20 km we observe the following results: Durban has a path loss value of 6.2 dB (obtained by extrapolation of Figure 4.42 (a)), while Botswana has a path loss value of 5.9 dB for this same height level and coverage range (see Figure 4.42(b)).
The analysis of Figure 4.39 – 4.42 above shows generally that the path loss value at the different coverage range and height level is higher in Durban than it is in Botswana. This is very much in agreement with our expectation, since as explained earlier, we are, at this stage analyzing the effect of diffraction fading. Diffraction fading is evident by incorporating k-factor into SPE to form the second modified parabolic equation (MPE2). Since Durban generally has a more hilly terrain compared to Botswana which has a flatter terrain, we expect Durban to have a higher path loss value than Botswana for this type of modifications and this is what our results in Figure 4.39 – 4.42 show.