PURPOSE: To reduce the size, weight, and cost of the equipment and to allow its enclosure to be designed freely without any thermal restriction by forming a heat pipe structure in an antenna, eliminating the need for a radiation fin, and cooling elements directly with external air.

CONSTITUTION: The antenna composed of the heat pipe structure having a fitting part for a power amplifying semiconductor element is provided, and its elements are connected to the electronic circuit in the envelope; and the elements are connected thermally to the antenna, which is arranged outside the envelope and put in operation. For example, a wick or groove is provided to the hollow internal wall and this equipment consists of the metallic antenna 10 made of the heat pipe structure charged with heat transport liquid, a heating element connected thermally to one terminal of the antenna 10, and a conduction part 3a which connects the circuit 2 to the element 3 electrically. The internal liquid is heated and vaporized because there is the heat pipe structure in the antenna 10 at the end of the element 3b, but the liquid is cooled through the antenna surface contacting the outside air to turn into liquid again and return to a heating part. Thus, the liquid is heated and cooled repeatedly to prevent the element 3b from overheating.