Machined Combline filters consist of short circuit stub resonators inductively coupled, to offer a low loss (high Q), rugged compact design. The resonators are capacitvely loaded and are typically 45 degrees long at their resonant frequency giving a very broad upper stopband with high levels of attenuation.

SARAS combline filters use rectangular (or circular) rods machined, generally, from solid aluminium to achieve low weight and are silver plated to give the lowest possible passband loss.

• Frequency Range: 100MHz to 18GHz

• Bandwidth: 1% to 40%

• Stopband: up to 6 x Fc

Interdigital filters use rectangular quarter-wave resonators, machined from solid, to offer symmetrical responses, even for very wideband filters. The electrical and mechanical characteristics are similar to combline but the resonators are longer and are alternatively inverted. The longer resonators produce a lower upper stopband frequency.

• Frequency Range: 800MHz to 20GHz

• Bandwidth: 1% to 50%

• Stopband: up to 2.5 x Fc