A quasi-elliptic bandpass filter has been designated based on substrate integrated waveguide cavity and parallel-coupled microstrip line (PCML). Two PCMLs are utilised to provide cross-coupling at both sides of the investigated filter. Electrical coupling intensity in the filter can be controlled by the proposed PCMLs which generate transmission zeros at sides of pass-band. Sharp sideband and significant out-of-band rejection are achieved.
A planar U-shaped resonator for measuring relative permittivity of the liquid mediums is developed. To improve the sensitivity of the proposed sensor, gap sections, coupled lines and central ring resonators (RRs) are used to enhance electric fields interact with liquid under test (LUT). Further to increase the resonance sharpness, a tapered double-sided spiral split RR is presented. As the permittivity of the LUT is increased from 26 to 79, the measured resonance frequency of the described sensor is varied in the 166.4-287.5 MHz range. The developed sensor exhibits an improvement in sensitivity of about 45% compared with the other work.
Design and realisation of a substrate integrated waveguide (SIW) planar sensor for the non-invasive monitoring of blood glucose concentration (BGC) is described. The structure of the presented sensor is similar to a conventional band-stop filter. To produce a substantial and localised field enhancement in the sensing region by the SIW technology, the slots and interdigital arms on the upper conductor of the SIW cavity are utilised. Further, the fingertip is used as materials under test and its displacement and fingerprints effects are studied. The introduced sensor is then fabricated and measured. The evaluated results indicate that the developed sensor features improvement in both the fingertip positioning and fingerprints effects compared to the other work. Also, the frequency resonance shift of the proposed sensor observing the valuable enhancement of non-invasive BGC detection sensitivity is much more than the previous study.
In this article, a modified rectangular resonant cavity consisting of a rectangular waveguide (RWG) and two frequency selective coupled (FSC) end‐plates with embedded parallel metallic strips (PMS) is proposed. The proposed FSC end‐plate converts the semi‐constant coupling mechanism of the conventional iris‐coupled end‐plate to the tunable FSC characteristics. This is due to adding capacitive coupling properties to inductive coupling characteristics of the conventional iris‐coupled end‐plate by embedding PMS inside the iris‐hole. So, the proposed FSC end‐plate enhances output power of the resonant frequency of the cavity. Consequently, the proposed modified cavity can determine the permittivity properties of the high‐loss specimens. Also, the parametric study of the effect of variation of the physical dimensions and position of these strips to tune and trim the performance of the proposed FSC end‐plate is presented. Also, the present study proposes an approach for determining the maximum complex permittivity with the rectangular resonant cavity perturbation method. Based on WR‐229 RWG specifications, conventional and investigated cavities are fabricated and measured. The evaluated results of the proposed configuration and conventional model indicate about 184% determination enhancement in the imaginary part of the dielectric constant. Also, this design is validated by distilled water specimen and TiO2 films at a various partial pressure of oxygen that are deposited by utilizing radio frequency magnetron sputtering technologies and their complex permittivity are determined by manufactured cavities.
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