23 research outputs found
Magnetic superlens-enhanced inductive coupling for wireless power transfer
We investigate numerically the use of a negative-permeability "perfect lens"
for enhancing wireless power transfer between two current carrying coils. The
negative permeability slab serves to focus the flux generated in the source
coil to the receiver coil, thereby increasing the mutual inductive coupling
between the coils. The numerical model is compared with an analytical theory
that treats the coils as point dipoles separated by an infinite planar layer of
magnetic material [Urzhumov et al., Phys. Rev. B, 19, 8312 (2011)]. In the
limit of vanishingly small radius of the coils, and large width of the
metamaterial slab, the numerical simulations are in excellent agreement with
the analytical model. Both the idealized analytical and realistic numerical
models predict similar trends with respect to metamaterial loss and anisotropy.
Applying the numerical models, we further analyze the impact of finite coil
size and finite width of the slab. We find that, even for these less idealized
geometries, the presence of the magnetic slab greatly enhances the coupling
between the two coils, including cases where significant loss is present in the
slab. We therefore conclude that the integration of a metamaterial slab into a
wireless power transfer system holds promise for increasing the overall system
performance
Multi-Channel Capacitive Sensor Arrays
In this paper, multi-channel capacitive sensor arrays based on microstrip band-stop filters are studied. The sensor arrays can be used to detect the proximity of objects at different positions and directions. Each capacitive sensing structure in the array is connected to an inductive element to form resonance at different frequencies. The resonances are designed to be isolated in the frequency spectrum, such that the change in one channel does not affect resonances at other channels. The inductive element associated with each capacitive sensor can be surface-mounted inductors, integrated microstrip inductors or metamaterial-inspired structures. We show that by using metamaterial split-ring structures coupled to a microstrip line, the quality factor of each resonance can be greatly improved compared to conventional surface-mounted or microstrip meander inductors. With such a microstrip-coupled split-ring design, more sensing elements can be integrated in the same frequency spectrum, and the sensitivity can be greatly improved