Active learning method for external Q computation

The external quality factor (Q_ext) of a resonator which represents the strength of the electromagnetic coupling between the resonant mode and the transmission mode of the feed line is an important parameter for designing microwave filters. Analytical computation of Q_ext needs exact determination of the field distribution around the coupling port. But the complexities of input/output ports in microwave/millimeter wave filters make this procedure completely complicated. In the case of some special resonators such as microstrip open loop resonators, lack of analytical solution for field distribution increases this complexity and results in time consuming full wave simulations. This paper proposes the use of active learning method (ALM) with ink drop spread (IDS) engine in computation of external quality factor of microstrip triangular open loop resonators (TOLR) in a vanishingly short time while keeping the accuracy. Using ALM based extracted Q_ext in the case of TOLR, a four pole chebychev bandpass filter was designed and fabricated. Very good agreement between the desired characteristics of the filter and the fabricated response shows the accuracy of the proposed approach.