An HTS lumped-element notch filter

This paper presents the measured results of an ultra-deep (90dB) HTS lumped-element notch filter matched over an octave-wide frequency range, which represents a previously unrealized portion of notch filter parameter space. The filter was realized using a seven-pole quasi-elliptic design and was fabricated in an HTS microstrip configuration. The fabricated notch filter has a stop bandwidth of 3 MHz, a 3 dB pass bandwidth of 8 MHz, and a center frequency of 1.03 GHz. The filter is well matched from 900 MHz to 1500 MHz with a 16 dB return loss. The passband noise figure was 0.3 dB. The measured data shows that the fabricated filter closely conforms to the simulation.