High-frequency power amplifier

A high-frequency power amplifier comprising:

• a transistor for amplifying a high frequency signal;
• a matching circuit of which an end is connected to an output terminal of the transistor, and of which another end is grounded;
• a first transmission line of which an end is connected to the output terminal of the transistor, the first transmission line having a length extending in a first direction from the output of the terminal of the transistor and a line width extending in a second direction perpendicular to the first direction;
• a second transmission line in which a line-width direction of an end line which is a line of an end portion thereof is aligned with a direction identical to the second direction in which theft line-width of the first transmission line extends, and in which an end thereof opposite to the end portion is connected to an output terminal;
• a first connecting member for connecting another end of the first transmission line and the end line of the second transmission line;
• plural island patterns of which ends are arranged in a vicinity of the first transmission line and of which other ends are arranged in a vicinity of the end line in the second transmission line;
• a second connecting member configured to connect an end of an island pattern and the first transmission line;
• and
• a third connecting member configured to connect another end of the island pattern and the end line of the second transmission line.