The Aaronia MDF940 Broadband Magnetic Field Tracking Antenna 9 KHz - 400 MHz is suitable for signal tracking and field strength measurements. This antenna measures the frequency range 9 kHz - 400 MHz. The MDF 940 can be combined with any spectrum analyzer or power meter to perform as a highly accurate field strength meter. Thanks to the high directionality of the antenna, the MDF is ideally suited for signal direction finding. The MDF 940 can be used as a radio direction finder or to locate illegal or unwanted interference.