4results about "Loop antennas with variable reactance" patented technology

A controllable electrical outlet may comprise a resonant loop antenna. The resonant loop antenna may comprise a feed loop electrically coupled to a radio-frequency (RF) communication circuit and a main loop magnetically coupled to the feed loop. The controllable electrical outlet may comprise one or more electrical receptacles configured to receive a plug of a plug-in electrical load and may be configured to control power delivered to the plug-in electrical load in response to an RF signal received via the RF communication circuit. The RF performance of the controllable electrical outlet may be substantially immune to devices plugged into the receptacles (e.g., plugs, power supplies, etc.) due to the operation of the resonant loop antenna. For example, degradation of the RF performance of the controllable electrical outlet may be less when the controllable electrical outlet includes the resonant loop antenna rather than other types of antennas.

A capacitively or inductively driven spiral antenna creates an electric current distribution of a dipole, which generates a sensible magnetic field for various military applications including detecting and pre-detonating improvised explosive devices (IEDs). The antenna includes a dielectric substrate, a spiral antenna, driving elements such as tuning forks or loop, and a coaxial cable that connects to a source terminal. The substrate is a low dielectric loss insulating material to provide support for the antenna. The spiral antenna is tuned to a natural frequency is disposed on the substrate. The coaxial cable extends from the substrate to the source terminal.

In some embodiments, a radio frequency identification (RFID) system may include at least one Ultra High Frequency (UHF) antenna component, a conductive loop having a largest dimension that is smaller than the wavelength of radiation transmitted at a Microwave Frequency (MW). The conductive loop may define a gap and an RFID chip may be electrically coupled to the conductive loop. The conductive loop may be configured to be resonant at an Ultra High Frequency (UHF) and less resonant at Microwave Frequency (MW). The antenna component may be selected from the group consisting of a dipole antenna, a monopole antenna, a loop antenna, or a slot antenna.