Testing device for coil shaped ferrite antennae - has two air cored test coils connected to ends of antenna to pick up magnetic coupling field

摘要

The testing device for coil shaped ferrite antennae has two air -cored test coils connected to the ends of the antenna. The coils pick up magnetic coupling field emanating from the antenna. Voltage induced in the coils is, after amplification, applied to a frequency monitoring circuit consisting of a trigger (8) whose keying ratio is adjustable, followed by a filter (10), rectifier (11) and a comparator (12) with adjustable switching threshold. Comparator (12) output signal is applied to a first input of an AND circuit (14) followed by a display unit (18). Coil voltage is also applied to an amplitude monitoring circuit consisting of a rectifier (15) followed by an adjustable amplitude comparator (16), whose output signal is applied to the other input of the AND circuit 14).