$P_{RX} = P_{TX} – L_{TX} + G_{TX} – L_{free space} – L_{misc. propagation} - L_{polarisation} + G_{RX} – L_{RX}$

Polarisation loss from heal can be calculated. It might also be worth working out losses due to heal and aerial directivity.

Distance (km)	Distance (nautical miles)	Frequency (MHz)		Loss (dB)
1		0.54				434			-85.2
1		0.54				869			-91.2
10		5.40				434			-105.2
10		5.40				869			-111.2
20		10.80				434			-111.2
20		10.80				869			-117.2
30		16.20				434			-114.7
30		16.20				869			-120.8
40		21.60				434			-117.2
40		21.60				869			-123.3
50		27.00				434			-119.2
50		27.00				869			-125.2
60		32.40				434			-120.8
60		32.40				869			-126.8