Case study 6

Determine the (clear sky) atmospheric attenuation to be expected for the following satellite signals at a reception site in Canberra. Assume a notional satellite position of 160oEast.

Solution 6

Assuming a 160 deg satellite the earth station elevation is 47deg.

If we assume moderate humidity (7.5 g/m3) the following values can be interpolated from the figure 22.

		Frequency       Total		
		(GHz)		Atmospheric			
				attenuation		
				(dB)		
		1.5		0.29		
		12		0.31		
		30		0.90       

From reference 7 (Ippolito) a table of values for a hot-humid climate (15 g/m3) yields the following values

		Frequency       Total		
		(GHz)		Atmospheric			
				attenuation		
				(dB)		
		1.5		0.29		
		12		0.39		
		30		1.66       

It is only at 20-30 GHz that atmospheric attenuation begins to have any real significance and even then it is much less important than rain attenuation.

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