The present disclosure may include, for example, a tunable capacitor having a decoder for generating a plurality of control signals, and an array of tunable switched capacitors comprising a plurality of fixed capacitors coupled to a plurality of switches. The plurality of switches can be controlled by the plurality of control signals to manage a tunable range of reactance of the array of tunable switched capacitors. Additionally, the array of tunable switched capacitors is adapted to have non-uniform quality (Q) factors. Additional embodiments are disclosed.

An antenna device is provided that can be designed easily and includes a flat antenna of which communication characteristics do not change significantly even when there exist metallic objects or the like in the surroundings. Moreover, the flat antenna is provided with an antenna-side signal line path conductor, an antenna-side first ground conductor, a matching circuit part, and an antenna-side connector part which are provided in an antenna-side insulator. The antenna device further includes a signal transmission cable that is provided with a radiation area setting part in the vicinity of a cable-side connector part. The antenna device is designed such that, by connecting the antenna-side connector part and the cable-side connector part to each other, substantially the entire surface of the flat antenna serves as a radiation part that radiates electromagnetic waves.

Various examples are provided for enhanced guided surface waveguide probes, systems and methods. In one example, a guided surface waveguide probe includes a charge terminal elevated over a lossy conducting medium, the charge terminal includes a upper terminal portion coupled to a lower terminal portion through a variable capacitance. A feed network is configured to couple an excitation source to the charge terminal and provide a voltage to the charge terminal with a phase delay that matches a wave tilt angle associated with a complex Brewster angle of incidence associated with the lossy conducting medium. In another example a method includes positioning a charge terminal over a lossy conducting medium, where the charge terminal includes an upper terminal portion coupled to a lower terminal portion through a variable capacitance. The method also includes adjusting a phase delay of a feed network to match a wave tilt angle associated with a complex Brewster angle of incidence associated with the lossy conducting medium, where the feed network is configured to couple an excitation source to the charge terminal and provide a voltage to the charge terminal with the phase delay.

A diplexer has a first terminal, a second terminal and a third terminal. The diplexer includes a first filter and a second filter. The first filter is connected between the first terminal and the third terminal. A first band signal is operated in a first frequency band and transmitted through a first path between the first terminal and the third terminal. The second filter is connected between the second terminal and the third terminal. A second band signal is operated in a second frequency band and transmitted through a second path between the second terminal and the third terminal. The first filter is a first band-rejection filter for stopping the second band signal.

A coupling circuit for power line communications includes a coupling transformer having first and second mutually coupled windings, with the first winding connectable to a power line. The second winding includes a pair of intermediate taps with one or more tuning inductor therebetween. The inductor or inductors are set between a first portion and a second portion of the second winding of the coupling transformer. A switch member is provided coupled with the inductor. The switch member is selectively actuatable to short-circuit the inductor.

A wide band radio frequency (RF) circulator, including: a first stage having four ports; and a second stage having four ports, wherein the first stage and the second stage are connected via a pair of conductive delay lines including a reciprocal delay line placed on a dielectric substrate and a non-reciprocal delay line placed on ferrite substrate, wherein each of the first stage and the second stage include a pair of couplers.

A tapped transmission line for distributing an electrical signal, such as an RF signal, to multiple modules, and/or aggregating signals from multiple modules. Embodiments of the invention provide a tapped transmission line based on a transmission-line medium along which tap elements are dispersed, so that the tap elements have a predominantly capacitive loading of the transmission-line medium. Methods for compensating the loss of the transmission-line medium are presented as well. Applications for distribution of transmitted signals, of local oscillator signals, and to aggregation of signals from multiple oscillators are disclosed. The invention is particularly applicable to integrated circuits (IC, ASIC, RFIC), and to multichannel RF systems such as phased array and MIMO systems.

A bandpass filter circuit includes a fourth element that is a capacitor having one end connected to a first node, a fifth element that is a capacitor having one end connected to a second node, a sixth element that is a capacitor connected between other end of the fourth element and other end of the fifth element, a seventh element that is an inductor having one end connected to a fourth node to which the fourth element and the sixth element are connected, other end of the seventh element is connected to a ground terminal, and an eighth element that is an inductor having one end connected to a fifth node to which the fifth element and the sixth element are connected, other end of the eighth element is connected to the ground terminal.

A first and second input tone are applied to a continuous-time complex filter within an integrated circuit. The magnitude of the output of the filter at the frequency of each of the first and second input tones are measured and compared to determine the value of a filter tuning control signal. A tuning control signal is applied to the filter with the determined value to tune the filter.

An impedance transformation circuit and a radio frequency power reliability test system are provided. The impedance transformation circuit can be used in a radio frequency power measurement system. The radio frequency power measurement system includes a signal generator, a buffer, a device under test, an attenuator, and a spectrum analyzer. The impedance transformation circuit includes a plurality of impedance transformers, which correspond to a plurality of impedance points on a reflection coefficient circle of a Smith chart, respectively. The impedance transformers are coupled between the device under test and the attenuator in turn in a radio frequency power reliability test, and the spectrum analyzer is configured to measure an output power corresponding to each of the impedance points, such that two of the impedance points respectively corresponding to a maximum output power and a minimum output power are found by the radio frequency power measurement system.