# Appendix B. Path Loss Calculations

## 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.

 Building Wireless Community Networks, Second Edition
 Preface
 Chapter 1. Wireless Community Networks
 Chapter 2. Defining Project Scope
 Chapter 3. Network Layout
 Chapter 4. Using Access Points
 Chapter 5. Host-Based Networking
 Chapter 6. Long-Range Networking
 Chapter 7. Other Applications