
241Microwave Components
used means to inject or remove energy from waveguides are probes, loops
and slots. Slots are also termed as apertures or windows.
7.3.1 Probe Coupling
Small probe carrying microwave energy inserted into a waveguide acts
as quarter-wave antenna. As illustrated in Figure 7.17a, a current-carry-
ing conductor is inserted into the waveguide. The most efficient place to
locate the probe is in the centre of a broader wall and parallel to the nar-
rower wall. Further, it has to be at one quarter-wavelength distance from
the end of the waveguide, which is to be shorted permanently or through
a movable (plunger) short (Figure 7.