TABLE OF CONTENTS The quadrature hybrid is another component that is more easily understood if you define the individual terms of its name. Just as with the directional coupler, doing that adds clarity to the explanation. The first term to define is quadrature. If you look up this term in the dictionary, you will find that this definition: "any two objects that are at right angles to one another." If, for example, you have two lines at right angles (90 ), they are in quadrature; if you have two tables at right angles, they are in quadrature; if you have two people at right angles, they are in quadrature. What we have in quadrature in the quadrature hybrid are the two output signals. They are 90 out of phase with one another in quadrature; that is, there are two outputs from a quadrature hybrid, and if you measure the phase relationship between them you will find a 90 difference. This is a valuable relationship to have, as we will see later on.
The term hybrid is actually the term hybrid junction. In that arrangement, transmission lines come together in such a manner that there is a high value of isolation between ports when it is used in a component. Figure 4.9 shows a quadrature hybrid and indicates the hybrid junction area. It can be seen that the hybrid junction is where the transmission lines overlap one another. When a quadrature hybrid is printed on a microwave circuit board,...
