ANTENNA DEVICE FOR DIRECTION FINDER

PURPOSE:To obtain a device having very simple mechanical construction and free of a failure by using an antenna where a conductor plate is arranged in parallel with a grounding base plate so as to obtain the directivity of a cardioid curve and turning its directivity by an electronic changeover switch. CONSTITUTION:The square conductor plate 2 is arranged via a suitable distance in parallel with the conductor base plate, two pairs of connecting sections 110, 111 and 120, 121 opposite with each other symmetrically to the center point are provided at four corners of the plate 2, and a coaxial cable 6 having a characteristic impedance equal to that between the conductor base plate and the conductor plate 2 is connected respectively to the connecting sections. The coaxial cable 6 is connected to a case of the electronic changeover switch, one of the connecting section of each pair is grounded via a resistor 25 having a characteristic impedance equal to said characteristic impedance in response to a positive or a negative control voltage applied to a terminal 15 or 20, and the other is connected to a receiver by a coaxial cable 9 of said characteristic impedance, and they are changed over sequentially at a prescribed period.