This calculator determines key parameters of a directional coupler, including coupling, coupling loss, insertion loss, and directivity, based on measured power levels. It accepts input power values in dBm or Watts for flexible use in RF testing and design.
Formulas
Coupling = -10 * log10( P4 / P1 )
Coupling Loss = -10 * log10( 1 – ( P4 / P1 ) )
Insertion Loss = -10 * log10( P2/P1 + P3/P1 + P4/P1 )
Directivity = -10 * log10( P3 / P4 )
Formula Explanation
- P1, P2, P3, and P4 represent input, transmitted, isolated, and coupled powers respectively.
- All results are expressed in decibels (dB) for standard RF measurement interpretation.
Example
Input: P1 = 0 dBm, P4 = -20 dBm, P3 = -40 dBm
Result: Coupling = 20 dB, Directivity = 20 dB
Who uses it
Useful for RF engineers and lab technicians analyzing signal coupling, isolation, and performance of couplers in microwave or communication systems.