Designing maximally flat quarter-wavelength-coupled filters using the Q distribution method

Four filter design examples are presented using the Q distribution (QD) method 1 to develop maximally flat quarter-wavelength-coupled transmission line filters accurately using arbitrary resonators. This article demonstrates the accuracy of the QD method using a variety of resonators and provides examples of the design procedure. Accordingly, each example employs a different type of resonator. The first example uses lumped-element bandpass resonators. The second and third examples use quarter- and half-wavelength tapped-stub resonators, respectively. The fourth example employs capacitively loaded half-wavelength tapped-stub resonators. The responses for these examples are approximately equal to the ideal maximally flat response, thereby further demonstrating the accuracy of the QD method.

Duke Scholars

Author William T. Joines Electrical and Computer Engineering