Compact Stripline Rejecting Bandstop Filter

The paper is devoted to simulation and designing of a compact stripline 4th-order bandstop rejecting filter. The BSF contains metallic case with dielectric substrate suspended inside. On one of the substrates surfaces a stripline structure forming common line and resonators electromagnetically coupled to it is placed. The ends of common line serve input and output ports. The resonators have very small coupling with each other due to their constructive features. At some distance between them the coupling becomes zero. This fact allows form the filter's stopband by proper choose frequency of each resonator. The filter’s substrate had relative dielectric constant εr = 80 and thickness h = 0.5 mm. The overall dimensions of the filter topology are 48.8×18.0 mm2. In the frequency band 1490.7 MHz…1509.3 MHz rejection exceeds 50 dB. Transmission bands at a level –1 dB are 0…1435 MHz and 1578 MHz…2425 MHz lower and upper correspondingly. Return loss in the passbands does not exceed –16 dB (VSWR≤1.4).