Ferrite-based junction circulators 1,2 are microwave devices made of at least three ports that have been widely used in emission/reception applications ensuring an isolation between the incoming and outgoing signals. They are especially useful in single antenna applications where signals are being transmitted and received simultaneously. Conventional circulators are based on a ferrite disk, magnetized to saturation, placed under the central conductor ensuring electromagnetic waves to propagate in a non-reciprocal manner. The external magnetic field allowing this saturation is provided by a permanent magnet positioned right above of the central conductor. Due to the size, weight, cost of these systems and the fact that high frequency applications are recently the main concern, the miniaturization of the circulator is inevitable. This can be achieved using self-biased hexagonal ferrite materials 3,4 which eliminates the use of a permanent magnet. These self-polarized materials, suitable for high frequency applications, are pellets made out of hexaferrite powder pressed and sintered. During pressing, the orientation of the particles should be achieved in the remanence state using an external magnetic field. In order to avoid the application of a magnetic field during pressing, and thus to minimize the cost of manufacturing circulators, we propose to design and manufacture circulators based on hexaferrite particles in the form of platelets. It has been shown that this platelet shape, as shown in Fig. 1, induces a self-alignment of the crystals with the particles orienting themselves spontaneously, therefore dropping the application of an external magnetic field in any way. This material will be then characterized using a coaxial cell capable of determining its dielectric and magnetic properties such as the permittivity and the permeability 5. The values obtained will then be used in the simulation of a coplanar circulator 6,7, that operates in the 5G band especially around 28 GHz, using HFSS simulator.

References
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