Although the interfering frequency differed considerably from the disturbed frequency, the strength of the received signal overwhelmed the receiving apparatus. Harmonic interference is the reception of a signal whose frequency is within the desired channel. None of the above cures is applicable to harmonic interference. Suppressing the offending harmonic with a notch filter or other type of filter, at the point of reception, is not possible without unacceptable degradation of the desired signal which is very near to or identical with the interfering harmonic frequency. Least cost suppression of harmonic interference consists of installing an appropriate filter at the transmitter causing the interference.
Harmonics are multiples of the transmitter frequency.
Therefore, the appropriate filter type is a lowpass filter capable of withstanding the transmit power level. Microwave Filter Company Inc. All rights reserved .