Filters
Microwave Filters
REMEC D&S builds microwave filters in many different physical configurations that have different performance characteristics and trade-offs. To design the best possible filter for your specific needs, specifications such as insertion loss, rejection roll-off, high power performance, phase linearity, group delay, size, and mechanical requirements must all be considered.
Lumped Element Filters
The resonator circuit elements in the filter are discrete (i.e., lumped). Inductors are realized using wire coils wound on cylindrical forms or flat straps. Capacitors are realized using parallel plate or multilayer chip devices.
Characteristics
- Small size
- Good Q factors: typically 100 to 300; capability from 300 to 700 depending on frequency
- Frequency ranges from DC to 26 GHz
- Bandwidth typically 2% to 60%; capability 1% to 160%
- Broad stopband
- Low to medium power handling: 1 W typical; capability to 100 W peak
Combline Cavity Filters
Combline cavity filters use coaxial transmission lines as distributed resonator elements (usually foreshortened or less than a quarter-wavelength). The filters are constructed as an array of individual coupled cavities fabricated in a single housing structure.
Characteristics
- Medium to large size
- High Q factors: typically 600 to 2000; capability to 6000
- Frequency ranges from 100 MHz to 26 GHz
- Bandwidths typically 0.5% to 60%; capability 0.01% to 100%
- High power handling: typically 1 kW peak; capability to 10 kW peak
Interdigital Filters
Interdigital filters use quarter-wavelength coaxial transmission lines as distributed resonator elements. The filters are constructed as an array of resonators in a single cavity housing. Interdigital filters, usually longer than combline filters for the same frequency and Q, offer a more symmetrical bandpass shape, flatter passband response, and wider bandwidth capability. These are excellent choices for flat group delay applications.
Characteristics
- High Q factors: typically 600 to 2000; capability to 6000
- Frequency ranges from 500 MHz to 26 GHz
- Bandwidths typically 50% to 100%; capability 20% to 160%
- High power handling: typically 1 kW peak; capability to 10 kW peak
