301results about "Loop antennas with variable reactance" patented technology

An antenna circuit and matching technique that cancels the inductive reactance of an antenna and thereby reduces the reactive voltage of the antenna are provided. Serial tuning capacitors are inserted along the conductor of the loop antenna as often as necessary to achieve a negligible instantaneous level of reactance on the antenna. The loop antenna is broken up into loop segments, where each segment may or may not have a serial capacitor depending on the desired performance criteria. Each capacitor is selected so as to have a reactance that effectively cancels the inductive reactance of a portion of the loop segment preceding the corresponding serial capacitor. The advantage is that the instantaneous level of reactance on antenna stays nulled, and thus any reactive voltage difference between loop segments remains negligible, even with high current flowing inside the antenna. Parasitics such as ohmic losses, internal capacitive loss and capacitive loss to the external world are all reduced. Moreover, the selected serial tuning capacitors are placed along the antenna wire to effect an average reactive voltage of substantially 0 volts across the antenna. The antenna is thus balanced about GND. Principles of reciprocity regarding passive antennas apply, so both transmitting and receiving antenna configurations are applicable.

A high density electronic package includes a low-modulus-of-elasticity flexible adhesive interposer substrate to which an electronic device, such as a semiconductor chip or die or other component, is attached. The flexible adhesive interposer substrate includes a sheet or layer of a molecularly flexible adhesive having via holes therein in which are built up conductive vias to which contacts of the electronic device connect. A thin layer of metal foil on one surface of the flexible adhesive sheet is patterned to provide contacts and to connect electrically to the conductive vias. The electronic device may be covered by a lid or by an encapsulant attached to the flexible adhesive interposer substrate and / or the electronic device. An electronic package may include a plurality of electronic devices and respective flexible adhesive interposers that are electrically interconnected.

Disclosed is a circuit and method for continuous automatic tuning of a resonant circuit. A resonance voltage of the resonant circuit is phase shifted by a predetermined phase shift Φ degrees and an input voltage signal to a power amplifier driving the resonant circuit is phase shifted by Φ±90 degrees to place the signals in quadrature. The phase shifted signals are mixed to obtain a error signal. The error signal is compared to a predetermined voltage range in order to generate control signals for a control word generator, such as an up-down counter. The control word generator produces a control word that drives a capacitance bank that is part of the resonant circuit. The present invention continuously automatically adjusts the capacitance of the capacitance bank to tune the resonant circuit.