A New Slot Line Broadband Isolator

The present paper is devoted to a study of displacement effect on a slot line structure. shown a broad frequency band of operation. An described. non reciprocal devices using a field First experimental results have isolator and a 4-port circulator are It is well known that the dominant mode on a slot line exhibits regions where the magnetic field is elliptically polarized, both in the substrate and in the air outside the substrate. It is possible to turn to good account this particularity for the design of non reciprocal microwave components, such as isolators, using a resonance effect. However, such a device does not offer a broad frequency band of operation. Other experiments achieved on various geometries of slot lines on a ferrimagnetic substrate have shown that it is possible to obtain a non reciprocal behaviour on a broad frequency band and this characteristic allows us to distinguish this mode of operation from the resonant one. To obtain this effect, a suitable choice of the slot line and substrate geometry and ferrimagnetic material is necessary. A field displacement effect then appears on a broad band (more than an octave). The direct wave is travelling along the slot line while the reverse one is travelling on the opposite side of the substrate. It is now possible to absorbe this reverse wave by the means of a lossy dielectric material or a ferrite used in a lossy region of polarization (figure 1).