The lossless T-junction divider suffers from the disadvantage of not being matched at all
ports, and it does not have isolation between output ports. The resistive divider can be
matched at all ports, but even though it is not lossless, isolation is still not achieved. From
the discussion in Section 7.1, however, we know that a lossy three-port network can be
made having all ports matched, with isolation between output ports. The Wilkinson power
divider [4] is such a network, with the useful property of appearing lossless when the output
ports are matched; that is, only reflected power from the output ports is dissipated.
The Wilkinson power divider can be made with arbitrary power division, but we will
first consider the equal-split (3 dB) case. This divider is often made in microstrip line or
stripline form, as depicted in Figure 7.8a; the corresponding transmission line circuit is
given in Figure 7.8b. We will analyze this circuit by reducing it to two simpler circuits
driven by symmetric and antisymmetric sources at the output ports. This “even-odd” mode
analysis technique [5] will also be useful for other networks that we will study in later
sections.