Absorptive Filter Prototype and Distributed-Element Absorptive Bandpass Filter

In this paper, we present a design methodology for absorptive bandpass filters. A filter prototype comprised of parallel resonators and admittance inverters has been developed. All design parameters in the filter prototype are given in terms of the center frequency, the bandwidth, the port impedance, and the normalized lumped-element lowpass filter prototype values. The presented filter prototype has been applied to the design of a third-order absorptive filter with distributed-type of filter centered at 3 GHz with the fractional bandwidth of 0.1. It is shown that the theory, the circuit simulation, the full-wave simulation, and the measurement are in a good agreement.