Miniaturized Substrate Integrated Waveguide Diplexer Using Open Complementary Split Ring Resonators

In this paper, two miniaturized planar diplexers based on the substrate integrated waveguide (SIW) structure loaded by open complementary split-ring resonators (OCSRRs) are proposed. The working principle is based on the theory of evanescent mode propagation. The proposed SIW diplexers operate below the cutoff frequency of the waveguide. Both the complementary split-ring resonators (CSRRs) and the OCSRRs behave as electric dipoles however, the resonance frequency of the OCSRRs is approximately half of the resonance frequency of the CSRRs. Therefore, the electrical size of the OCSRRs is larger than the CSRRs. Accordingly, the OCSRRs are more appropriate for the SIW miniaturization. At first, the filtering response of the SIW structure loaded by OCSRR unit cells is investigated. Then, two miniaturized SIW diplexers which consist of two cascaded OCSRR unit cells with different orientations are designed. For the first diplexer (Type I), the fractional bandwidths of operation for the up and down channels are 9.52% and 2.59% at 4.2 GHz and 5.8 GHz, respectively. For the second diplexer (Type II), the fractional bandwidths of operation for the up and down channels are 5.95% and 2.51% at 4.7 GHz and 5.6 GHz, respectively. Finally, in order to validate the ability of the proposed OCSRR unit cells in the size reduction, two designed diplexers are fabricated and experimental verification are provided. A good agreement between the results of measurement and simulation is achieved. The proposed diplexers show significant advantages in terms of size reduction, low loss, high isolation, and integration with other planar circuits

The diagnosis of early fetal cardiac changes of the gestational diabetic mothers: Presenting the preload index

Objectives: To evaluate fetal cardiac changes in gestational diabetic mothers, compared to healthy ones by means of different indices and to determine which index can first represent the alterations. Methods: The study was conducted as an observational cross-sectional study, including 25 pregnant women with gestational diabetes as the cases and 50 healthy pregnant women as the controls. The preload index, left and right side myocardial performance index (MPI), Interventricular septal hypertrophy, the left and right side cardiac output were assessed in all the patients. Results: The gestational ages were 31.65 ± 8.02 and 31.64 ± 5.37 weeks in case and control group respectively, without any significant difference. Both of the left and right ventricular MPI did not differ statistically between the case and controls. The cases had a greater Interventricular septal hypertrophy but the cardiac output was similar. The preload index was higher in the fetuses of the gestational diabetic mothers. Conclusions: In our study, the MPI did not show any difference between the fetuses of the gestational diabetic mothers and non-diabetic ones; but, fetuses of gestational diabetic mothers had a greater value of PLI, representing early diastolic function changes in right heart even before the overt heart failure occurred. This could be a sign of vasculopathy in gestational diabetic mothers. Copyright © 2019, Author(s)

A Novel Compact Dual Notch Band Filter Based on Metamaterial Concept

Using composite right-left handed (CRLH) transmission line concept, a novel miniaturized dual notch band filter (DNBF) is proposed. The suggested DNBF consists of an interdigital transmission line (ITL), split ring resonators (SRRs) and complementary split ring resonators (CSRRs). Since the resonance frequency of the SRRs and CSRRs are quite independent of each other, the dual notch bands of the proposed filter can be separately controlled and shifted by changing the dimension of the SRRs and CSRRs. In this paper, the reject bands are designed for WLAN (2.4 GHz) and WiMAX (3.5 GHz) to reject these frequency bands from the ultra-wide band communication systems. The simulation results show that the transmission response has more than 32 dB rejections near each band. To validate the design concept, the proposed NBPF has been fabricated and tested. Experimental verification is provided and good agreement has been found between simulation and measurement. To the best of our knowledge, the proposed NBPF is more compact in comparison with other reported filters