Disclosed are apparatus and methods related to junction ferrite devices having improved insertion loss performance. In some implementations, a ferrite disk assembly can be configured for a radio-frequency (RF) circulator. The disk assembly can include a ferrite-based disk having a ferrite portion and a metalized layer formed on a grounding surface of the disk to improve electrical contact between the grounding surface of the disk with an external grounding surface. The ferrite-based disk can further include a dielectric portion disposed around the periphery of the ferrite center portion. In some embodiments, the metalized layer can be a silver layer formed on the grounding surface of the disk and having a desired thickness.