Tunable ultra-high frequency filter with variable capacitance tuning devices

A tunable ultra-high frequency filter comprising at least one variable capacitance tuning device incorporating first and second coaxial fingers fitted up in the filter, the first finger being a hollow cylindrical body having an external diameter with an end face at least partly flat, and the second finger comprising a cylindrical body having the same external diameter with an end face at least partly flat, extended with a plunger having a diameter much smaller than the external diameter of the cylindrical bodies which is displaceable relative to the first finger between a minimum and a maximum penetration positions where the plunger and the hollow body of the first finger have minimum and maximum facing surfaces for determining a first capacitance variation, said two cylindrical bodies being displaceable relative to one another, the variable distance between the corresponding flat faces determining a second capacitance variation.