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Appendix B. Path Loss Calculations

Here is a simple table of path loss calculations in free space for channel 1 with clear line of sight (the difference in path loss from channel 1 to channel 11 is negligible). See Chapter 6 shows how to use these numbers to figure out how far your network can reach. Distances are in miles; losses are in dB.

Distance (in miles)

Losses on channel 1 (in dB)

0.5

98

1

104

2

110

3

114

4

116

5

118

7

121

10

124

15

128

20

130

25

132

30

134

The path loss table above was calculated with the following formula, rounded up to the nearest whole number:

L = 20 log(d) + 20 log(f) + 36.6

Check out ARRL online (http://www.arrl.org) for what might be the most authoritative source of radio information on the planet. Their excellent books (in particular, UHF/Microwave Experimenter's Manual and The ARRL Antenna Book) are the definitive sources for learning about microwave communications.

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