Figure 2

Schematic of a notch-port and butt-port coupled resonators. Top-down view. Metalized areas of the structure are shown in grey, non-metalized are shown in pink. The feedline is connected to transmission lines with impedances \(Z_{\mathrm{i}}\) and \(Z_{\mathrm{o}}\) (not to scale). The length of the coupler, open and shorted sections are \(l_{\mathrm{c}}\), \(l_{\mathrm{o}}\), \(l_{\mathrm{s}}\), respectively. (a) \(\lambda/4\) CPW resonator notch-port coupled to a transmission line, (b) \(\lambda/4\) CPW resonator inductively butt-port coupled to a transmission line, (c) \(\lambda/4\) CPW resonator capacitively butt-port coupled to a transmission line with input impedance \(Z_{\mathrm{i}}\). (d) TL schematic of the general case with arbitrary terminations of the resonator \(Z_{\mathrm{t1}}\) and \(Z_{\mathrm{t2}}\) and feedline \(Z_{\mathrm{o}}\) and \(Z_{\mathrm{i}}\).