The current invention, by using a plurality of conductive fiber brush bundles and a coaxial line to transfer RF signal(s) between relatively rotatable objects, creates easy-maintenance, long duration a RF rotary joint with soft contacting rotational interfaces. It consists of a stationary shield conductor assembly, a stationary core conductor assembly, a rotational shield conductor assembly with a tapered round head, a rotational core conductor assembly with a tapered round head, and rotational and stationary insulating assemblies with a central bore. Both stationary and rotational shield conductor assemblies having a conductive fiber brush bundle, which further containing a plurality of hair-thin conductive filaments to form a symmetrical flexible tube. The interfaces of the core soft contacting rotational and the shield soft contacting rotational are formed between the free end portions of the conductive fiber brush bundles and the tapered round head of the rotational cone conductor and rotational shield conductor respectively.