Familiarization with the Microwave Laboratory Equipment.

Which of the following is the ferrite device that buffers a microwave source from the effects of a varying load, and thereby prevents the formation of standing waves?
Low-power Gunn diodes are replacing:
The most widely used microwave antenna:
Directivity of a directional coupler signifies the direction of power flow in the coupler.
In coupled line directional couplers, power from one line to another is transmitted through a microstrip line running between them.