Bird Technologies - The RF Experts
Second Harmonic Filters
Second Harmonic Filters
The ferrite used to make circulators is a non-linear material that generates a significant amount of 2nd harmonic power which can contribute to the formation of 3rd order intermodulation products when mixed with other transmitter carriers. For this reason, either a bandpass cavity filter or a harmonic filter must always be installed between the isolator and the antenna. Bird manufactures single and dual-section filters for applications where bandpass cavities are not used.