Patent ID: 8121574

Claim:
A loop-type directional coupler comprising a hollow, planar, or co-axial waveguide in the form of a half-loop antenna including a first arm and a second arm, for contactless coupling-out of a forward signal “a” and a backward signal “b” on said waveguide, including having the first arm connected to a first input of a first network and the second arm connected to a second input of the first network, the first network having a first power divider at the first input and a second power divider at the second input, dividing the respective signals applied to the arms of the antenna, the first network including a first adder which adds together the signals from the first and second power dividers and feeds the signal Kc(a+b) resulting from the addition, where Kc is a capacitive coupling factor of the loop-type directional coupler, to a first output of the first network, and a first subtractor which subtracts the signals from the first and second power dividers from one another and feeds the signal Ki(a−b) resulting from the subtraction, where Ki is an inductive coupling factor of the loop-type directional coupler, to a second output of the first network, and including a third network having a first input connected to the first output of the first network and having a second input connected to the second output of the first network, the third network including a third power divider at the first input and a fourth power divider at the second input, dividing the respective signals applied to the inputs of the third network, the third network including a second adder receiving the resultant signal from the third power divider via a first capacitive signal path having a complex transmission factor D1 and the resultant signal from the fourth power divider via a first inductive signal path having a complex transmission factor D2 and which adds these signals together and feeds the signal resulting from the addition to a first output of the third network, the third network including a second subtractor which receiving the signal from the third power divider via a second capacitive signal path having a complex transmission factor D3 and the signal from the fourth power divider via a second inductive signal path having a complex transmission factor D4 and which subtracts these signals from one another and feeds the signal resulting from the subtraction to a second output of the third network, there being arranged in at least one of the signal paths between the first and third networks or in at least one of the signal paths between the power dividers and the second adder and second subtractor, or both, at least one coupling-factor matcher which alters the magnitude or phase, or both magnitude and phase, of the signal on the given signal path in such a way that signals having coupling factors K1, K2 which are identical in respect of magnitude and phase are present for addition and subtraction at the second adder and second subtractor respectively.