🔍 Key Concepts

• How waveguides carry electromagnetic energy at microwave frequencies • How energy is normally coupled into a hollow metal waveguide from a transmitter • Difference between radiating antennas and small probes/loops used inside a waveguide

💭 Think About

• Think about what kind of coupling structure fits physically inside a rectangular or circular metal waveguide and can excite the internal field pattern. • Which of the options is commonly used in microwave engineering to launch and extract power from waveguides? • Which choices describe methods better suited for low‑frequency or lumped circuits rather than high‑frequency waveguides?

✅ Before You Answer

• Identify which option corresponds to a small probe or loop that can be inserted through the waveguide wall. • Eliminate any options that sound like lumped‑element components (R, L, C type circuits) instead of distributed microwave structures. • Ask whether the chosen method can practically match impedance and efficiently transfer power at microwave frequencies in a hollow conductor.