Abstract: According to one embodiment, a waveguide bend includes a metal block. The metal block includes a first waveguide, a second waveguide and a third waveguide. The first waveguide, the second waveguide and the third waveguide are integrally formed. The second waveguide includes a bend at which a propagation direction of a radio wave is changed. An opening size of the second waveguide is smaller than an opening size of the first waveguide. The third waveguide is provided between the first waveguide and the second waveguide. An opening size of the third waveguide is smaller than the opening size of the first waveguide and is larger than the opening size of the second waveguide.

Abstract: According to one embodiment, a waveguide bend includes a metal block. The metal block includes a first waveguide, a second waveguide and a third waveguide. The first waveguide, the second waveguide and the third waveguide are integrally formed. The second waveguide includes a bend at which a propagation direction of a radio wave is changed. An opening size of the second waveguide is smaller than an opening size of the first waveguide. The third waveguide is provided between the first waveguide and the second waveguide. An opening size of the third waveguide is smaller than the opening size of the first waveguide and is larger than the opening size of the second waveguide.

Abstract: A power amplification device configured to switching-amplify a high-frequency input signal and output a switching-amplified signal. The device includes a feedback circuit configured to output a feedback signal including a portion of the switching-amplified signal; a subtractor configured to output an error signal indicating a difference between the input signal and the feedback signal; a comparator configured to compare the error signal with a threshold voltage and generate an on/off pulse signal based on a result of the comparison; a one-shot circuit configured to be set in an on-state for a time period using a rising timing of the pulse signal as a trigger; and an amplifier configured to switching-amplify the input signal by a logical OR between the generated on/off pulse signal and an output signal from the one-shot circuit, and output the switching-amplified signal.

Abstract: According to one embodiment, a power amplification device configured to switching-amplify a high-frequency input signal into an output signal includes a feedback circuit, a subtractor, a comparator, an output tuning circuit, a constant voltage controlled power supply, and an amplifier. The feedback circuit is configured to output a portion of the output signal as a feedback signal. The subtractor is configured to output a difference between the input signal and the feedback signal as a error signal. The comparator is configured to generate an on/off pulse signal by comparing the error signal with a predetermined threshold voltage. The output tuning circuit is configured to resonate to a frequency of the input signal. The amplifier is configured to generate the output signal by switching-amplifying the input signal according to on/off of pulse signal, and output the output signal to the output tuning circuit.

Abstract: A Doherty microwave amplifier having a main amplifier and a peaking amplifier, distributing and inputting an input signal to the main amplifier and the peaking amplifier to obtain an output signal by combining an output from the main amplifier and an output from the peaking amplifier, comprises a first coupler which branches and outputs a part of the input signal, a second coupler which branches and outputs a part of the output signal, and a bias control unit which feedback-controls a bias signal to the peaking amplifier, based on a difference between a level of a signal branched and output from the first coupler and a level of a signal branched and output from the second coupler.

Abstract: A Doherty microwave amplifier having a main amplifier and a peaking amplifier, distributing and inputting an input signal to the main amplifier and the peaking amplifier to obtain an output signal by combining an output from the main amplifier and an output from the peaking amplifier, comprises a first coupler which branches and outputs a part of the input signal, a second coupler which branches and outputs a part of the output signal, and a bias control unit which feedback-controls a bias signal to the peaking amplifier, based on a difference between a level of a signal branched and output from the first coupler and a level of a signal branched and output from the second coupler.