Equivalent Circuit Model Results Research Articles

Realization of high performance PZN-PT single crystal based piezoelectric flexural mode hydrophone for underwater sensor applications

In this article, attempts are made to grow large size PZN-PT single crystals using high temperature solution growth method by implementing novel bottom cooling technique. The grown crystals are oriented and poled along 〈001〉 direction and obtained larger piezoelectric strain coefficient (d33 > 2000 pm V−1) suitable for development of underwater acoustic sensor requirements. Flexural mode hydrophone is realized using the oriented PZN-PT single crystal discs. Finite element modeling is employed to examine the design of the flexural mode hydrophone and an equivalent circuit model is also applied to study its acoustic characteristic at two extreme boundary conditions like simply supported and clamped edge condition. The underwater acoustic response of the PZN-PT single crystal based flexural mode hydrophone is evaluated over the frequency range (100 Hz to 12 kHz) and its responses are compared with the FEM and equivalent circuit model results. The predicted results from FEM and equivalent circuit model are found to be in good agreement with the experimental results. The receiving sensitivity of the PZN-PT single crystal-based hydrophone is 12 dB higher than the PZT 5A based hydrophone in the frequency range of 2 kHz to 6 kHz. The fabricated PZN-PT single crystal-based hydrophone offers better performance than the conventional piezo ceramic based flexural hydrophone.

SELF-QUADPLEXING SLOT ANTENNA FOR S- AND C-BAND APPLICATIONS

This paper demonstrates a novel kind of cavity-backed self-quadplexing slot antenna for S- and C-band applications. The proposed antenna consists of four distinct U-shaped slots of different lengths and produces quad frequency bands for wireless communication systems. These slots are excited through separate and orthogonally placed 50 Ω micro-strip feed lines and generate four distinct operating bands at 3.2, 4.1, 5.8, and 7.2 GHz. Due to the perturbation of the different U-shaped slots over a substrate-integrated waveguide cavity with defined positions, the high intrinsic port isolation value is better than 30.5 dB. Thus, the proposed unique antenna structure combines the four independent operating bands with minimum mutual coupling and negligible interference among the input ports, showing the antenna's self-quadplexing feature. The proposed antenna also has frequency tunability with unidirectional radiation patterns and gains of 5.8, 5.4, 4.01, and 3.47 dBi at corresponding operated frequencies. The cross polarization is below 17.3 dB and the front-to-back ratio is higher than 21.5 dB at all operating quad bands. Good agreement was obtained between the simulated |S| parameter and equivalent circuit model results.

Self-quadplexing slot antenna for S and C-band applications

This paper demonstrates a novel kind of cavity-backed self-quadplexing slot antenna for the S and C-band applications. The proposed antenna consists of 4 distinct “U”-shaped slots of different lengths and produces the quad frequency band for wireless communication systems. These slots are excited through the separate and orthogonal placed microstrip feed lines of 50 Ω; generates four distinct operating bands at 3.2 GHz, 4.1 GHz, 5.8 GHz, and 7.2 GHz. Due to the perturbation of different U-shaped slots over the substrate integrated waveguide (SIW) cavity with defined positions, the high intrinsic port isolation value is better than 30.5 dB. Thus, the proposed unique antenna structure combines the four independent operating bands with minimum mutual coupling and negligible interference among input ports, which shows the self-quadplexing feature of the antenna. The proposed antenna also has the property of frequency tunability with uni-directional radiation pattern and gain of 5.8 dBi, 5.4 dBi, 4.01 dBi, and 3.47 dBi at corresponding operated frequency. The cross-polarization is 17.3 dB and the front-to-back ratio higher than 21.5 dB at all operating quad bands. There is a good agreement between simulated |S|-parameters results and equivalent circuit model results.

Self-quadplexing slot antenna for S and C-band applications

This paper demonstrates a novel kind of cavity-backed self-quadplexing slot antenna for the S and C-band applications. The proposed antenna consists of 4 distinct “U”-shaped slots of different lengths and produces the quad frequency band for wireless communication systems. These slots are excited through the separate and orthogonal placed microstrip feed lines of 50 Ω; generates four distinct operating bands at 3.2 GHz, 4.1 GHz, 5.8 GHz, and 7.2 GHz. Due to the perturbation of different U-shaped slots over the substrate integrated waveguide (SIW) cavity with defined positions, the high intrinsic port isolation value is better than 30.5 dB. Thus, the proposed unique antenna structure combines the four independent operating bands with minimum mutual coupling and negligible interference among input ports, which shows the self-quadplexing feature of the antenna. The proposed antenna also has the property of frequency tunability with uni-directional radiation pattern and gain of 5.8 dBi, 5.4 dBi, 4.01 dBi, and 3.47 dBi at corresponding operated frequency. The cross-polarization is 17.3 dB and the front-to-back ratio higher than 21.5 dB at all operating quad bands. There is a good agreement between simulated |S|-parameters results and equivalent circuit model results.

Modified double dumbbell-shaped split-ring resonator-based negative permittivity metamaterial for satellite communications with high effective medium ratio

Metamaterial with negative permittivity demonstrate excellent performance in cutting-edge technology. Thus, this study modified the double dumbbell-shaped split-ring resonator (MDD-SRR) based negative permittivity for satellite communications. The proposed MDD-SRR unit cell comprises a square-shaped split-ring resonator and two dumbbell-shaped rings. Some parts of the outer square ring were extended to enlarge the electrical length which altered the inductance of the metamaterial unit cell. The dimension of the proposed unit cell is 9 × 9 × 1.524 mm3, fabricated on a Rogers RT6002 (lossy) substrate material. Based on the results, five resonances for the transmission coefficient were achieved at frequencies of 2.896 GHz, 8.11 GHz, 9.76 GHz, 12.48 GHz and 13.49 GHz, including the S, X and Ku band satellite communication frequency bands through numerical simulation in a high-frequency electromagnetic simulator Computer Simulation Technology (CST) microwave studio. Negative permittivity at frequencies ranging from 2.896–3.76 GHz, 8.11–8.592 GHz, 9.76–10.784 GHz, 12.496–12.768 GHz, 13.504–14.4 GHz, were observed and extracted using the Robust and Nicolson–Ross–Weir (NRW) methods. Meanwhile, an effective medium ratio (EMR) measured at 11.51 to 2.896 GHz specified the goodness of the metamaterial unit cell for satellite communication with higher bandwidth and gain. The simulated, circuit model and measured results that were compared for validation purposes indicated that the simulation results, the equivalent circuit model results and measured results occupied each other. Moreover, the numerical simulation of the double dumbbell-shaped metamaterial unit cell was performed using a High-Frequency Structure Simulator (HFSS) to confirm the results. To evaluate the parametric study, the proposed unit cell was subjected to change different substrate types, change of split gap of rings, change of direction of electromagnetic field propagation, and structural optimization. In conclusion, the S, X and Ku-bands in the proposed metamaterial are competent for satellite communications as they are also investigated using an array of a unit cell.