A directional coupler (2) includes a main line (11), a sub-line (12), a variable terminator (13), and a variable filter circuit (15). The variable terminator (13) is a variable impedance circuit that terminates one end portion of the sub-line (12). The variable filter circuit (15) is connected to the other end portion of the sub-line (12). The variable filter circuit (15) may include a filter, a bypass path, and a switch which is connected to at least one of the filter and the bypass path.

A method for achieving uniformity in an etch rate is described. The method includes receiving a voltage signal from an output of a match, and determining a positive crossing and a negative crossing of the voltage signal for each cycle of the voltage signal. The negative crossing of each cycle is consecutive to the positive crossing of the cycle. The method further includes dividing a time interval of each cycle of the voltage signal into a plurality of bins. For one or more of the plurality of bins associated with the positive crossing and one or more of the plurality of bins associated with the negative crossing, the method includes adjusting a frequency of a radio frequency generator to achieve the uniformity in the etch rate.

A radio-frequency assembly is described which can be used in communication satellites, for example. The radio-frequency assembly contains a signal source in the form of a semiconductor amplifier output, an impedance matching filter, and a radio-frequency waveguide. The impedance matching filter is connected to the semiconductor amplifier output on the input side and to the radio-frequency waveguide on the output side. The impedance matching filter has a different impedance value on the input side from that on the output side and is matched to the semiconductor amplifier output on the input side and matched to the radio-frequency waveguide on the output side. Consequently, a separate matching circuit between semiconductor amplifier output and radio-frequency waveguide is no longer necessary.

A radio-frequency assembly is described which can be used in communication satellites, for example. The radio-frequency assembly contains a signal source in the form of a semiconductor amplifier output, an impedance matching filter, and a radio-frequency waveguide. The impedance matching filter is connected to the semiconductor amplifier output on the input side and to the radio-frequency waveguide on the output side. The impedance matching filter has a different impedance value on the input side from that on the output side and is matched to the semiconductor amplifier output on the input side and matched to the radio-frequency waveguide on the output side. Consequently, a separate matching circuit between semiconductor amplifier output and radio-frequency waveguide is no longer necessary.

A switchable reactance unit includes an RF terminal configured to connect to a transmission line for transmitting a signal at a frequency in a range of 1 - 200 MHz, and a switching arrangement comprising a plurality of switching elements used in parallel. Each switching element has a control terminal, and is connected to the RF terminal via at least one individual reactance assigned to the switching element and connected in series with the switching element. The switching elements are controllable or controlled via their control terminals in such a way that they switch simultaneously.

The invention relates to a directional coupler comprising a non-straight main conductor line for receiving a high power signal and at least one coupling element. The main conductor line is arranged to run in a plane P.sub.0. The at least one coupling element is arranged sectionally parallel to the main conductor line. Further, the invention relates to a method for measuring RF voltage and/or RF power using a directional coupler. The method comprises the steps of combining the measured signals of the directional coupler and the measured voltage and current values of the VI sensor unit. In case, one of the measured signals has a low or zero level the sensitivity of the measuring of RF voltage and/or RF power is increased.

The invention relates to a directional coupler comprising a non-straight main conductor line for receiving a high power signal and at least one coupling element. The main conductor line is arranged to run in a plane P.sub.0. The at least one coupling element is arranged sectionally parallel to the main conductor line. Further, the invention relates to a method for measuring RF voltage and/or RF power using a directional coupler. The method comprises the steps of combining the measured signals of the directional coupler and the measured voltage and current values of the VI sensor unit. In case, one of the measured signals has a low or zero level the sensitivity of the measuring of RF voltage and/or RF power is increased.

Disclosed are apparatuses and methods of tuning a radio frequency circuit using stub tuners and photoconductive switches. In one aspect an electromagnetic stub tuner apparatus is disclosed. the apparatus includes a transmission line, and a photoconductive switch positioned along the length of the transmission line. The photoconductive switch is configured to turn on or turn off, wherein an impedance of the transmission line is changed when the photoconductive switch is turned on compared to when the photoconductive switch is turned off. In another aspect, a method of tuning a radio frequency circuit is disclosed. In yet another aspect, a method of producing a radio frequency tuning circuit is disclosed.

Disclosed are apparatuses and methods of tuning a radio frequency circuit using stub tuners and photoconductive switches. In one aspect an electromagnetic stub tuner apparatus is disclosed. the apparatus includes a transmission line, and a photoconductive switch positioned along the length of the transmission line. The photoconductive switch is configured to turn on or turn off, wherein an impedance of the transmission line is changed when the photoconductive switch is turned on compared to when the photoconductive switch is turned off. In another aspect, a method of tuning a radio frequency circuit is disclosed. In yet another aspect, a method of producing a radio frequency tuning circuit is disclosed.

In one embodiment, a system includes an RF source and an RF impedance matching circuit receiving RF power from the RF source. The matching circuit includes at least one variable reactance element, a sensor operably coupled to a component of the matching circuit, and a control circuit. The control circuit receives a signal from the sensor indicative of a parameter value. Upon determining the parameter value meets a first predetermined condition, the control circuit transmits a control signal to the RF source causing the RF source to carry out a power control scheme. The power control scheme causes the RF source to reduce or maintain the RF power without turning off the RF power.