Page 203 - Satellite Communications, Fourth Edition
P. 203
Antennas 183
Phase shifters Amplifiers Antennas
A
A
Input
A
A
(a)
Input A
(b)
Figure 6.34 (a) Active, and (b) passive array configura-
tions.
Electronic scanning can be achieved in one of several ways. The phase
shift coefficient of a transmission line is given by 2 >l , where l is
the wavelength of the signal passing along the line. A section of trans-
mission line of length l introduces a phase lag (the output lags the input)
of amount
l (6.43)
Phase shift can be achieved by changing either l or . The concept of
changing the length l is illustrated in Fig. 6.35. Making the shorter
