Bandreject filters (or notches) are used to pass a large operating band of frequencies, while rejecting a narrow band of frequencies. This band of frequencies may have a 3 dB bandwidth as small as 0.5% or as large as 30 or 40%. The band reject filter is designed for each customers specific frequency applications.

Lumped Component: Used for wider bandwidth notches - 10% to 30 or 40% - and for frequencies below 150 MHz.

Helical Resonator: Used for narrow bandwidth notches - 0.5% to 5% - and center frequencies of 30 to 400 MHz.

Coaxial Resonator: Used for narrow bandwidth applications - 0.5% to 5% - for center frequencies of 400 to 3,000 MHz.