Effect of a co-channel monotone interference on the response of a microwave band reject filter

This paper presents the theory and experiment on the effects of a co-channel interfering tone on the frequency response of a microwave band reject filter designed at a centre frequency of 10 GHz. The filter's flat band reduces from 300 MHz in absence of interference to 250 MHz in presence of interference. Experiment shows that the band reject filter fails to eliminate the unwanted frequency band due to the presence of the interfering tone at 9.845 GHz.