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.

Methods and apparatus are disclosed for communicating between an aircraft and a terminal when the aircraft is on the ground. The connection between the aircraft and the terminal is made over a ground power line while the aircraft is being supplied with power. The ground power line comprises one or more wires, which are typically unshielded and cause radio interference. At the transmitting end, multiple copies of the same signal offset in phase relative to one another over the ground power line. Each data stream is coupled to a respective wire in the ground power line. At the receiving end, the multiple copies of the signal are extracted from the respective wires of the ground power line and combined to generate a combined signal with improved signal-to-noise ratio. Radio interference is suppressed by transmitting the data streams in a phase offset manner so that the unwanted emissions cancel.

A circuit device includes: a transmitting circuit that performs transmission of a signal by current-driving signal lines in a transmission period; a receiving circuit that receives a signal that a transmitting circuit of a communication partner has transmitted by current-driving the signal lines, in a reception period that is different from the transmission period; and terminating resistor circuits that can be connected to the signal lines, and whose resistance value in the transmission period is set to a value that is smaller than a resistance value in the reception period.

Aspects of the subject disclosure may include, for example, a system for detecting an accumulation of a liquid on a transmission medium that may interfere with the propagation of guided electromagnetic waves on a surface of the transmission medium, and directing a device to remove at least a portion of the liquid accumulating on the surface of the transmission medium to mitigate the interference. Other embodiments are disclosed.

Aspects of the subject disclosure may include, a communication device with a group of radio devices connected with a support structure, where the support structure is positioned in and passes through housing openings in each radio device to provide a stacked arrangement. One or more radio device is rotatable with respect to the support structure to enable adjusting a first orientation of a directional antenna therein. Other embodiments are disclosed.

Aspects of the subject disclosure may include, a communication device with a support structure having first and second annular contacts formed on an outer surface thereof, a first radio device having a first inner surface of a first housing opening with a third contact, and a second radio device having a second inner surface of a second housing opening with a fourth contact. The support structure is positioned in and passes through the first and second housing openings thereby positioning the first and second radio devices in a stacked arrangement, and, when in the stacked arrangement, the first and third contacts are aligned and the second and fourth contact are aligned to provide a coupling between the first and second radio devices. Other embodiments are disclosed.

A main power line (+ and lines) is coupled to a power supply, for example a car battery, grounded to a vehicle chassis. Positive and negative main power lines are coupled to a power line gateway module, and spliced to carry power for a segment, until receiving, by splices, RF power line communcations. The main power lines, now carrying power and RF power line communications are then coupled to remote modules. RF power line communication carries signal from the power line gateway module to a impedance matching network or a transformer are used to match impedances.

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.

Either one of a communication device and a communication device comprises a direct current power supply configured to generate a direct current for serial communication from alternating current power supplied from an alternating current power supply through a power line and a common line and pass the generated direct current through a current loop. Either the communication device or the communication device comprises an adjuster configured to adjust the impedance between a signal line and the common line based on the voltage between the signal line and the common line (530).

A control unit of a communication device provides multicast precoding information from at least first beamforming information descriptive for a first transmission channel and second beamforming information descriptive for a second transmission channel. A precoder unit beamforms at least one signal using the multicast precoding information to obtain at least two precoded signals. A transmitter circuit which is electrically coupled to the precoder unit multicasts transmission signals through the at least first and a second transmission channels, wherein the transmission signals are derived from the precoded signals.