Filtering device and filtering assembly having an electrically conducting strip structure

A filter device with an electrically conducting strip structure, comprising:

• a transmission line formed by an electrically conducting strip printed on a surface of an electrically insulating substrate, said conducting strip having two ends respectively forming the two sole input and output connection ports of the filter device,
• a plurality of resonators, each resonator comprising an electrically conducting strip printed on said surface of the substrate,
• wherein:
• the conducting strip of each resonator has a first end coupled to the transmission line between the two connection ports and at least one second end that is free or connected to a ground so as to create an effective fundamental resonant wavelength specific to each resonator on said surface of the substrate, and
• for each pair of neighbouring resonators of the plurality of resonators, a distance between the first ends of two neighbouring resonators of the pair is less than one tenth of a smallest effective fundamental resonant wavelength of the plurality of resonators on said surface of the substrate.