  The polarization vector (PV) of an electromagnetic wave (EW) will experience
a rotation in a region of spacetime perturbed by gravitational waves (GWs).
Based on this idea, Cruise's group has built an annular waveguide to detect
GWs. We give detailed calculations of the rotations of the polarization vector
of an EW caused by incident GWs from various directions and in various
polarization states, and then analyze the accumulative effects on the
polarization vector when the EW passes n cycles along the annular waveguide. We
reexamine the feasibility and limitation of this method to detect GWs of high
frequency around 100 MHz, in particular, the relic gravitational waves (RGWs).
By comparing the spectrum of RGWs in the accelerating universe with the
detector sensitivity of the current waveguide, it is found that the amplitude
of the RGWs is too low to be detected by the waveguide detectors currently
running. Possible ways of improvements on detection are discussed also.
