RF Engineering for Wireless Networks

Chapter 6 Propagation

1. Propagation in Free Space

Imagine a wireless local area network (WLAN) somewhere in interstellar space. (Ignore for the moment the question of how we got there and what we’re doing with a WLAN so far from home, and for that matter the magnetized plasma background likely to be present in an interstellar environment.) The received signal is just a time-delayed attenuated version of the transmitted signal. The received power is described by the Friis equation 5.40 in terms of the transmitted power, the distance between transmitting and receiving antennas, and the directive gains of the respective antennas (Figure 6-1). Propagation is independent of wavelength, direction, and polarization (recall that the factor of λ²