Magneto-inductive waveguide devices

Devices formed from magneto-inductive waveguides based on coupled loop resonators are considered using simple analytic theory, initially assuming lossless propagation and nearest-neighbour coupling. Two-port devices that were considered include mirrors, Fabry–Perot resonators, Bragg gratings and tapers, while more general N-port devices include power splitters and directional couplers. Conditions for multiple-beam resonance and Bragg reflection in two-port devices are identified, and it is shown that quasi-optical filters may be constructed by simple layout variations. Conditions for low reflection are identified in splitters, and it is shown that matched three-port splitters with arbitrary power division ratios may be achieved for a particular input port. However, matching is not possible for all ports simultaneously. Directional couplers are shown to operate well only at mid-band and with weak coupling. The effect of loss is then examined and it is shown that idealised performance is obtained using resonators with sufficiently high Q-factors.