A directional coupler with three or more holes is sometimes

A directional coupler with three or more holes is sometimes used in preference to the two-hole coupler:

1. Because it is more efficient
2. To increase coupling of the signal
3. To reduce spurious mode generation
4. To increase the bandwidth of the system

A directional coupler with three or more holes is sometimes used in preference to the two-hole coupler to increase the bandwidth of the system.