These directional couplers calculations are based on textbook equations and conditions where all four ports are assumed to be terminated in impedances that are exactly matched to the characteristic impedance of the coupler, and that perfectly linear operation occurs. The "Directivity" term accounts for non-ideal isolation between the coupler input and the isolated port. The "Mainline Loss" term exists to account for resistive losses in the coupler (a specification often provided by the manufacturer). Here are definitions of the terms used.
Input (Port 1)
Main system signal input
Transmitted (Port 2)
Main system signal output
Coupled (Port 3)
Power sampled from Port 1 (forward, or incident)
Isolated (Port 4)
Power sampled from Port 2 (reverse, or reflected)
Coupling Factor
Amount of power sampled relative to the input
Mainline Loss
Resistive losses not due to coupling
Directivity
Difference between Port 3 and Port 4
Isolation
Difference between Port 1 and Port 4
Coupling Losses Only
Theoretical reduction in output power relative to the input due to power lost to the coupled and isolated ports.
Note: Numbers shown are NOT total page views; they are unique IP addresses for each 24-hour period (i.e., unique visitors). Typical page view counts are at least twice the reported unique visitor number.
RF Cafe Erie, PA (814) 833-1967
A Disruptive Web Presence™ GPS Coordinates: N 42°04.577', W 080°11.757'
