This calculator allows you to evaluate the performance of a directional coupler by calculating the coupling, coupling loss, insertion loss and directivity from the powers measured on its ports. It facilitates the analysis of RF devices used to monitor or divide signal power.
Ideal for RF engineers, measurement technicians and transmission system designers wanting to verify the quality and efficiency of their directional couplers.
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)
Explanation of formulas
- P1 is the input power of the coupler.
- P2, P3 and P4 are the powers measured on the different output ports.
- Coupling represents the fraction of power extracted for measurement or control.
- Directivity expresses the ability of the coupler to isolate the signal in a single direction.
Example of calculation of a directional coupler with P1 = 100 mW and P4 = 1 mW
Input : P1 = 100 mW, P4 = 1 mW
Output : Coupling = 20 dB
Benefits and uses
- Allows you to verify the accuracy of RF power measurements.
- Useful for characterizing couplers in the laboratory or in the field.
- Facilitates control of the directivity and performance of the device.
- Essential tool for the development and maintenance of RF communications systems.