Hy-Q International ’s range of quartz crystal filters are suitable for applications that require selective narrow-band filtering at HF and VHF frequencies.
Because of the extremely high Q of quartz resonators crystal filters with a fractional bandwidth of the order of 0.01% to 0.5% can be realised with low insertion loss and high selectivity. Hy-Q International employs modern computer aided design techniques covering conventional crystal filter realisations and polylithic realisations. The conventional approach, using discrete crystal resonators, is employed at low frequencies and where the selectivity or bandwidth requirements are such that complex realisations are necessary, as in HF SSB filters. The polylithic approach, using cascaded monolithic dual filter elements, is used at higher frequencies where the selectivity and bandwidth requirements allow.