An electromagnetic, EM, device, includes: a three-dimensional, 3D, body having a dielectric material, the 3D body having a first dielectric portion, 1DP, and a second dielectric portion, 2DP, wherein the 1DP is at least partially but not completely embedded within the 2DP; wherein the 1DP and the 2DP each have a dielectric material other than air; wherein the 1DP and the 2DP each have a planar cross-section profile perpendicular to a particular linear axis of the 3D body that is constant along the particular linear axis; wherein at least a portion of the 3D body is a dielectric resonator, DR.