PURPOSE: To eliminate the need for any special direction finder and to detect the incoming directions of radio waves easily by inserting a resistor which separates both end parts of a conductor forming a frame type antenna electrically.

CONSTITUTION: A resistor 2 is inserted in the central part of a frame type antenna 1, and the antenna 1 is connected to the primary side of a transformer 4. The primary side and secondary sides of the transformer 4 are grounded at one end. Therefore, the output of the antenna 1 is applied via the transformer 4 to a coaxial cable 5. Since the conductors 10 and 11 of the antenna 1 forming both end parts thereof are electrically separated by the resistor 2, the respective conductors act as independent vertical antennas. The output of the antenna 1 and the output of the vertical antenna formed of the conductor 11 on the nongrounding side are applied on the primary side of the transformer 4, and the combined output thereof is transmitted from the secondary side.