Link Budget

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

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)	Fresnel r (m)
1		0.54				434			-85.2		13.1
1		0.54				869			-91.2		9.3
10		5.40				434			-105.2		41.6
10		5.40				869			-111.2		29.4
20		10.80				434			-111.2		58.8
20		10.80				869			-117.2		41.5
30		16.20				434			-114.7		72.0
30		16.20				869			-120.8		50.9
40		21.60				434			-117.2		83.1
40		21.60				869			-123.3		58.7
50		27.00				434			-119.2		92.9
50		27.00				869			-125.2		65.7
60		32.40				434			-120.8		101.8
60		32.40				869			-126.8		71.9

• https://www.internetsociety.org/wp-content/uploads/2017/10/Link-Budget-Calculation.pdf
• https://www.erau.ee/et/ultraluehilained/78-uncategorised/477-vhf-uhf-microwave-radio-propagation-a-primer-for-digital-experimenters