An active mechanical waveguide including an ultrasonically-transmissive material and a plurality of reflection points defined along a length of the waveguide may be driven at multiple resonant frequencies to sense environmental conditions, e.g., using tracking of a phase derivative. In addition, frequency-dependent reflectors may be incorporated into an active mechanical waveguide, and a drive frequency may be selected to render the frequency-dependent reflectors substantially transparent.

An active mechanical waveguide including an ultrasonically-transmissive material and a plurality of reflection points defined along a length of the waveguide may be driven at multiple resonant frequencies to sense environmental conditions, e.g., using tracking of a phase derivative. In addition, frequency-dependent reflectors may be incorporated into an active mechanical waveguide, and a drive frequency may be selected to render the frequency-dependent reflectors substantially transparent.

An impedance converter includes an insulating layer; a first wire provided on a first surface of the insulating layer and extending in a first direction; a second wire provided on a second surface of the insulating layer and extending in the first direction and face the first wire, the second surface being located on a side opposite to the first surface; a third wire provided on the first surface and extending in a second direction orthogonal to the first direction; a fourth wire provided on the second surface and extending in the second direction and face the third wire; a fifth wire provided on the first surface and extending in the second direction; and a sixth wire provided on the second surface and extending in the second direction and face the fifth wire.

An impedance converter includes an insulating layer; a first wire provided on a first surface of the insulating layer and extending in a first direction; a second wire provided on a second surface of the insulating layer and extending in the first direction and face the first wire, the second surface being located on a side opposite to the first surface; a third wire provided on the first surface and extending in a second direction orthogonal to the first direction; a fourth wire provided on the second surface and extending in the second direction and face the third wire; a fifth wire provided on the first surface and extending in the second direction; and a sixth wire provided on the second surface and extending in the second direction and face the fifth wire.

A surface wave generator is proposed. The generator may include a radiator configured to generate an electromagnetic field based on a signal externally applied. The generator may also include a first dielectric substrate on a top of the radiator and a second dielectric substrate on a bottom of the radiator. The generator may further include a first surface wave generation member on a bottom of the second dielectric substrate, a first geometric pattern being deposited on a top of the first surface wave generation member. The generator may further include a third dielectric substrate on a bottom of the first surface wave generation member. The generator may also include a second surface wave generation member between the third dielectric substrate and a metal surface, a second geometric pattern different from the first geometric pattern and being deposited on an upper surface of the second surface wave generation member.

Aspects of the subject disclosure may include, for example, a transmission medium for propagating electromagnetic waves. The transmission medium can include a core for propagating electromagnetic waves guided by the core without an electrical return path, a rigid material surrounding the core, wherein an inner surface of the rigid material is separated from an outer surface of the core, and a conductive layer disposed on the rigid material. Other embodiments are disclosed.

Aspects of the subject disclosure may include, systems, apparatuses, and methods for determining that a load associated with a transmission medium exceeds a first threshold, wherein the transmission medium guides a first electromagnetic wave that propagates along the transmission medium from a first waveguide device to a second waveguide device without requiring an electrical return path, and based on the determining that the load exceeds the first threshold, enabling an injector to supply power to the transmission medium utilizing a very low frequency (VLF) generator. Other embodiments are disclosed.

Aspects of the subject disclosure may include, systems, apparatuses, and methods for determining that a load associated with a transmission medium exceeds a first threshold, wherein the transmission medium guides a first electromagnetic wave that propagates along the transmission medium from a first waveguide device to a second waveguide device without requiring an electrical return path, and based on the determining that the load exceeds the first threshold, enabling an injector to supply power to the transmission medium utilizing a very low frequency (VLF) generator. Other embodiments are disclosed.

Aspects of the subject disclosure may include, for example, a transmission medium for propagating electromagnetic waves. The transmission medium can include a plurality of cores for selectively guiding an electromagnetic wave of a plurality of electromagnetic waves longitudinally along each core, and a shell surrounding at least a portion of each core for reducing exposure of the electromagnetic wave of each core. Other embodiments are disclosed.

Aspects of the subject disclosure may include, for example, a transmission medium for propagating electromagnetic waves. The transmission medium can include a plurality of cores for selectively guiding an electromagnetic wave of a plurality of electromagnetic waves longitudinally along each core, and a shell surrounding at least a portion of each core for reducing exposure of the electromagnetic wave of each core. Other embodiments are disclosed.