A cavity type Band Pass Interdigital Filter has been designed and developed using electrically conducting liquid: Mercury. This filter has an Insertion loss of -5.0 dB at a Center frequency of 4.46 Ghz and a 1:2 VSWR Bandwidth of 63 Mhz respectively. Further, the property of thermal expansion of liquids, under certain specific & controlled conditions has been utilized, to vary the characteristics of this filter. This has been achieved by exercising suitable control over temperature (external-environmental) and pressurization (internal) of certain components/parts made of liquid: mercury while fabricating the Interdigital filter. The development of this Interdigital filter has demonstrated that: "it's possible to shift/move the frequency-band window of the filter by few tenths of megahertz's in the frequency domain".
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