QuinStar Technology series QFL Low Pass filters provide high rejection level and steep skirt selectivity for frequencies above the band edge or corner frequency. Their pass band has low insertion loss over full standard waveguide bands. The lower band edge is establishes by the cut-off frequency of the waveguide for all standard models. These filters have a very wide rejection band that covers up to three times the highest pass band frequency. Series QFL filters are well suited as harmonic filters and as pre-selectors for receivers. They can be employed to remove undesirable sideband or spurious signals from converters for receivers and transmitters. These filters also find applications in test equipment such as network analyzers and signal generators to eliminate or minimize sub-harmonics, harmonics and spurious signals.
Standard products are offered in seven waveguide bands covering 18-110 GHz. Figure below shows the characteristics of these types of filters. Series QFL and QFH filters can be combined to create a very broad bandpass filter with distinct advantages.