Patent ID: 8237614

Claim:
A planar antenna including an antenna section and a peripheral circuit section on an identical substrate, the planar antenna comprising: a radiating element that is arranged in the antenna section; a peripheral circuit that is arranged in the peripheral circuit section; a microstrip line that connects the peripheral circuit and the radiating element to feed electricity from the peripheral circuit to the radiating element; a first ground conductor that is intended for the peripheral circuit and is arranged on a back side of a first area where the peripheral circuit is arranged; a second ground conductor that is intended for the microstrip line, is arranged on a back side of a second area where the microstrip line is arranged, and has a width smaller than that of the first ground conductor, a connection between the radiating element and the microstrip line being located on the side of the second area where the microstrip line is arranged, away from the first area where the peripheral circuit is arranged; a third area that is arranged away from the first area with the second area therebetween; and a third ground conductor that is intended for the microstrip line and is arranged on a back side of the third area.