Aspects of the subject disclosure may include, a system that facilitates receiving a first electromagnetic wave propagating along a transmission medium, detecting, according to the first electromagnetic wave, an obstruction on a first portion of an outer surface of the transmission medium, responsive to the detecting the obstruction, configuring a material to have similar properties to the obstruction, the material being positioned along a second portion of the outer surface of the transmission medium, and generating a second electromagnetic wave that propagates along the transmission medium without relying on an electrical return path to facilitate propagation of the second electromagnetic wave along the transmission medium, the material facilitating propagation of the second electromagnetic wave from the second portion of the outer surface of the transmission medium to the first portion of the transmission medium affected by the obstruction. Other embodiments are disclosed.

Aspects of the subject disclosure may include, a system that facilitates receiving a first electromagnetic wave propagating along a transmission medium, detecting, according to the first electromagnetic wave, an obstruction on a first portion of an outer surface of the transmission medium, responsive to the detecting the obstruction, configuring a material to have similar properties to the obstruction, the material being positioned along a second portion of the outer surface of the transmission medium, and generating a second electromagnetic wave that propagates along the transmission medium without relying on an electrical return path to facilitate propagation of the second electromagnetic wave along the transmission medium, the material facilitating propagation of the second electromagnetic wave from the second portion of the outer surface of the transmission medium to the first portion of the transmission medium affected by the obstruction. Other embodiments are disclosed.

A THz waveguide is described, comprising four conductive wires separated by an air gap, the THz waveguide allowing low-loss and dispersion-free propagation of a THz signal. The system for terahertz polarization-division multiplexing comprises at least two THz sources, a THz waveguide and a THz receiver, wherein said THz waveguide comprises four conductive wires separated by an air gap; THz pulses from the THz sources being coupled into the THz waveguide; the THz waveguide transmitting the THz pulses independently, the THz waveguide operating as a broadband polarization-division multiplexer. The method for terahertz polarization-division multiplexing, comprising multiplexing THz pulses from terahertz sources in free-space, coupling resulting multiplexed THz pulses into a THz waveguide comprising four conductive wires separated by an air gap; and demultiplexing the multiplexed THz pulses after propagation in the waveguide.

A THz waveguide is described, comprising four conductive wires separated by an air gap, the THz waveguide allowing low-loss and dispersion-free propagation of a THz signal. The system for terahertz polarization-division multiplexing comprises at least two THz sources, a THz waveguide and a THz receiver, wherein said THz waveguide comprises four conductive wires separated by an air gap; THz pulses from the THz sources being coupled into the THz waveguide; the THz waveguide transmitting the THz pulses independently, the THz waveguide operating as a broadband polarization-division multiplexer. The method for terahertz polarization-division multiplexing, comprising multiplexing THz pulses from terahertz sources in free-space, coupling resulting multiplexed THz pulses into a THz waveguide comprising four conductive wires separated by an air gap; and demultiplexing the multiplexed THz pulses after propagation in the waveguide.

According to one embodiment, disclosed is an antenna comprising: a first waveguide having a first signal transmission path; a second waveguide connected to the first waveguide; and an antenna unit connected to the second waveguide and having a first opening, wherein the second waveguide comprises a first separator for separating the signal transmission path, and the antenna unit comprises a first antenna unit and a second antenna unit.

A surface wave excitation device includes a transmission line disposed on a wire layer PCB, and a same quantity of layers are respectively disposed above and below the wire layer PCB. A copper wire is disposed on each layer of PCB, and the copper wire forms a closed region. Closed regions on the PCB that are respectively disposed above and below the wire layer PCB and that have a same distance from the wire layer PCB are in a same shape, and a closed region on a PCB farther away from the wire layer PCB occupies a larger area. The wire layer PCB includes first and second closed regions, the first closed region is disposed on one side of the transmission line, and the second closed region is disposed on the other side, and shapes of the first and second closed regions are mutually symmetrical with the transmission line as a symmetry axis.

A surface wave excitation device includes a transmission line disposed on a wire layer PCB, and a same quantity of layers are respectively disposed above and below the wire layer PCB. A copper wire is disposed on each layer of PCB, and the copper wire forms a closed region. Closed regions on the PCB that are respectively disposed above and below the wire layer PCB and that have a same distance from the wire layer PCB are in a same shape, and a closed region on a PCB farther away from the wire layer PCB occupies a larger area. The wire layer PCB includes first and second closed regions, the first closed region is disposed on one side of the transmission line, and the second closed region is disposed on the other side, and shapes of the first and second closed regions are mutually symmetrical with the transmission line as a symmetry axis.

A sensor with a mechanical waveguide may be characterized using test ultrasonic signals to generate a baseline signature, and the baseline signature may later be used to detect faults in the sensor.

A sensor with a mechanical waveguide may be characterized using test ultrasonic signals to generate a baseline signature, and the baseline signature may later be used to detect faults in the sensor.

An interconnect structure for insertion loss reduction in signal transmission and a method thereof are disclosed. In an embodiment, an interconnect is formed on a substrate by chemical etching process, and when the interconnect is protected by photoresist in chemical etching process, the etching direction of etching solution is not oriented, so undercut areas are respectively formed on both sides of a bottom of the interconnect at contact of the interconnect and the substrate because of etching solution residue after the etching process. An included angle formed in the undercut area between the interconnect and the substrate is defined as an etch angle, and a length of the portion, exposing in the undercut area, of the substrate is defined as an etch length. Controlling sizes of the etch angle and the etch length can reduce an insertion loss in signal transmission.