Dual-band filter for an IFF/ADS-B reception chain

A dual-band analogue filter configured to be passing for IFF signals received in a first frequency band (fQ01-fQ02) centered on the 1030 MHz frequency and ADS-B signals received in a second frequency band (fA01-fA02) centered on the 1090 MHz frequency, and to reject signals received outside the first frequency band and the second frequency band, in particular at least one frequency band (fQ2-fA1) between the first frequency band and the second frequency band, said dual-band analogue filter being implemented using multi-planar technology, and comprising a plurality of superimposed layers, including, in succession:

• a first layer comprising an input port and an output port,
• a second layer comprising a ground plane having openings facing the input port and the output port,
• a third layer comprising N band-pass resonators, with N being greater than or equal to 1, and
• a fourth layer comprising N band-stop resonators;
• wherein the elements of said layers are arranged such that:
• the N band-pass resonators are connected in pairs by electromagnetic coupling (K1,2, K2,3, K3,4, K4,5, K5,6),
• a first resonator of the N band-pass resonators is connected to the input port by electromagnetic coupling (Qe,s),
• a last resonator of the N band-pass resonators is connected to the output port by electromagnetic coupling (Qe,1), and
• each band-pass resonator is connected to one of said band-stop resonators by electromagnetic coupling (KS,1, KS,2, KS,3, KS,4, KS,5, KS,6).