How to test the performance of the Directional coupler

1. Testing Signal Transmission Performance

Connect the signal source to the main input end of the coupler
Connect the power meter to the main output end and the secondary output end respectively
Compare the power difference between the input signal and main output signal to determine if the insertion loss is within reasonable range
Observe the power of the secondary output signal to evaluate if the coupling degree meets design requirements
If main signal attenuation is too large or no secondary output signal exists, it indicates abnormal signal transmission

Requires a bidirectional signal source
First inject signal into the positive input end and record secondary output power
Then connect signal source to reverse input end and measure secondary output power
The difference between measurements is the directionality index (larger difference indicates better directionality)
If difference is too small, the coupler cannot effectively distinguish signal direction (reverse signal interference problem)

Perform tests at different frequencies, adjusting signal source frequency from low to high
At each frequency point, measure:
- Main circuit insertion loss
- Coupling degree of auxiliary circuit
- Isolation degree
Draw curves showing how each indicator changes with frequency
Determine if coupler maintains stable performance within designed frequency range
Significant deviation in any frequency band indicates abnormal performance

Conduct through appearance inspection and environmental testing
Check for:
- Shell deformation
- Loose, worn, or damaged interfaces
- Unobstructed heat dissipation structure
Place coupler in vibration or extreme temperature environment
Retest electrical performance after environmental exposure
Significant parameter changes indicate mechanical structure or material stability issues