Transmission line model for coupled rectangular double split‐ring resonators

Abstract

stage filter has a measured central frequency of 3.25 GHz and a À3 dB bandwidth of 50 MHz. Its minimum passband insertion loss is approximately 1.6 dB, which includes the extra loss caused by the subminiature A (SMA) connectors. Its return loss at center frequency is better than À19 dB. Figure 7 shows the simulated (dashed line) and measured (solid line) frequency responses of the filters. The one-pole filter has a measured center frequency of 2.23 and a À3 dB bandwidth of 15 MHz. Its minimum passband insertion loss is approximately 2.5 dB, which includes the extra loss caused by the SMA connectors. Its return loss at central frequency is better than À15 dB. CONCLUSIONSIn this work, CSRs are proposed and their characteristics are investigated. A novel SIW loaded by CSR filter is designed.Compared to conventional CSRR, the new structure has better performance on miniaturization. A lower frequency passband is obtained in SIW filter. Therefore, CSR is a better candidate than CSRR for miniaturized substrate SIW filter applications. The results from our analysis and experiments are in good agreement with each other.

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“…The measured insertion loss is about 4 dB. For both measurements, the difference between the measurements and EM numerical solver can be improved if the mesh density is increased [6].…”

“…where f m and f n are two natural resonance frequency from the estimated insertion loss of the coupled resonators [10]. The coupled asymmetric multiple transmission lines can be used to build the impedance network to accurately characterize the coupling effect between the neighboring cells [6]. To keep the elementary DSRRs unchanged, only the cell separation distance D ij…”

“…This work focuses on filter design by using coupled transmission line model as shown in Figure 1. The authors works [5,6] have shown the decent estimation accuracy of narrow band EM behavior of DSRR structures by using coupled transmission line formulation for microstrip realization. This model also allows to estimate resonant frequencies variation with respect to some critical dimension parameters and extract unloaded/loaded quality factors from single unit cell for filter design.…”

“…Based on the filter specifications, the required coupling coefficients between neighboring DSRRs can be calculated from low-pass prototype parameters [7]. Since coupled DSRRs can be accurately characterized by using asymmetric coupled multiple transmission lines [6], the calculated coupling coefficients are realized by optimizing the coupling distance between neighboring cells. To experimentally verify the filter design procedure, a band-stop filter and its complementary structure employing via holes are demonstrated.…”