Interdigital filters use coupled rods one quarter of a wavelength long, shorted at alternate ends. Therefore no end capacitance is required, which simplifies the structure compared with a combline filter at the expense of larger size. They are higher Q than the combline filter and can be designed for wider bandwidths. However stopband is interrupted by passbands at 3x, 5x etc the passband frequency.
The Interdigital Structure is normally used for bandpass filters and diplexers.
Frequecny Range 300MHz to 20GHz
Bandwidths 1% to 50%
Stopband up to 2.9 x CF depending and passbandwidth.
Most connectors can be fitted.