To provide a microstrip antenna capable of surely scanning radio wave beams in a target direction even in a switching element having a plurality of output terminals such as FET and to provide a high frequency sensor with improved detection accuracy.
In the microstrip antenna provided with: a substrate; a ground electrode; a feeding element to which a high frequency signal is fed; a parasitic element disposed separately from the feeding element only by a prescribed inter-element space; a switch for switching whether to electrically short-circuit an input terminal and an output terminal or to open them; a first transmission line, the one end of which is connected to the parasitic element and the other end of which is connected to the input terminal; and a second transmission line provided on the substrate, the one end of which is connected to the output terminal, if the parasitic element is energized when the switch is short-circuited, the first transmission line has length by which the antenna gain of the parasitic element is zero or below when the switch is opened.
TSUBOI HIROYUKI
IWATA KENGO
NAGAISHI MASAYUKI
