Our Filters

Our Custom Filters

General
A filter allows desired signals to pass in the passband, while undesired frequencies are suppressed in the stopband
by a certain level of attenuation. There will always be some loss of signal in the passband due to dissipation within
the filter (insertion loss) and reflection caused by an impedance mismatch with the terminating load (return loss).
A perfect filter would allow all desired signals to pass and it would reject all undesired signals completely. However,
in the real world, there is a transition area between the two bands. The smaller the transition area, the steeper the
slope of the filter.

Most of these factors are interdependent and one can be improved at the cost of another. For example, the insertion
loss varies inversely to band width, but directly with steepness of slope. The dimensions of a filter are also largely
dependent on the above factors. A cavity filter's dimensions - for example - are determined by its frequency, which
influences the length of the resonators. Also, its bandwidth, stopband attenuation and steepness of slopes
determine the diameter and number of resonators and therefor its overall dimensions.

The filter designs we specialize in are:

LC-Filters: Filters constructed with inductors & capacitors. This type of design allows for great flexibility in filter
responses (such as Chebyshev or Cauer/Elliptic) and allows for smaller build-up sizes.

Cavity Filters: Filters constructed with resonators within conducting enclosures. This type of design achieves steeper
slopes and narrower stopbands (higher selectivity). However, the design is limited by spurious resonances and VSWR
considerations.
Helical Filters: Filters constructed with helical resonators. This type of design allows for lower frequency filters to be
built in smaller housings.