As previously discussed, when a small probe is inserted into a waveguide and supplied with
microwave energy, it acts as a quarter-wave antenna. Current flows in the probe and sets up an E field
such as the one shown in figure 1-39A. The E lines detach themselves from the probe. When the probe is
located at the point of highest efficiency, the E lines set up an E field of considerable intensity.
Figure 1-39A.Probe coupling in a rectangular waveguide.
Figure 1-39B.Probe coupling in a rectangular waveguide.
Figure 1-39C.Probe coupling in a rectangular waveguide.