2021/2
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- ItemParametric Geometrical Study of OOO-Microstrip Circuit with Dual-Band Bandpass NGD Behavior(Společnost pro radioelektronické inženýrství, 2021-06) Yang, Rong; Wan, Fayu; Nebhen, Jamel; Lallechere, Sebastien; Ravelo, BlaiseThis paper introduces a bandpass (BP) NGD circuit design engineering. The developed circuit is de¬signed and implemented using distributed microstrip tech-nology and operates with outstanding dual-band bandpass NGD performance added with low attenuation. The BP NGD topology presents an innovative geometrical shape represented by an OOO (triple O) structure composed of multi-parameter parallel transmission lines (TLs) based elements. The OOO type NGD circuit is mainly composed of different physical length TLs and two identical coupled lines (CLs). Then extensive parameter NGD analyses are elaborated to investigate on the influences of each physical size of OOO circuit on the NGD performances. Through the difference of physical length of transmission line, the delay can be adjusted. Through the results of simulation and measurement, it can be seen that the center frequency points are about 0.75 GHz and 1.46 GHz respectively, and the time delay is about –1.83 ns and –2.6 ns respectively.
- ItemStudy on the Composite Electromagnetic Scattering from 3D Conductor Multi-Objects above the Rough Surface(Společnost pro radioelektronické inženýrství, 2021-06) Liu, Ting; Zhang, Lin; Zeng, Zhi-Guo; Wei, Sheng-JunThe traditional algorithm for the composite electromagnetic scattering from 3D conductor multi-objects above the rough surface has such weaknesses as slow computation speed and large memory consumption. On the basis of the fast algorithm integrated with the traditional coupling method of moment and physical optics method, this paper uses the multilevel fast multipole method (MLFMA) and fast far-field approximation (FAFFA) to accelerate the multiplication of matrix vector between the object and environment, which greatly improves the computation speed and reduces the memory consumption. This paper adopts the dual Debye sweater permittivity model simulate the real sea surface environment, establishes the coupling MoM-PO model of composite scattering from multi-objects on and above the sea surface, and obtains the composite electromagnetic scattering coefficient in virtue of the interaction between object area and rough surface area calculated by the MLFMA and FAFFA. At the same time, the changes of composite scattering coefficient along with the change of object spacing, size, incident angles, tilt angle, type and sea surface wind speed are analyzed in detail. The computation results show that the hybrid method consisting of the method of moment accelerated by MLFMA and FAFFA and physical optics method brings higher accuracy and computation efficiency (the computation time and memory consumption are 62% and 82% of the method of moment respectively).
- ItemAmplitude-modulated, Cosine PE and WP Pulses: Theory and Applicability(Společnost pro radioelektronické inženýrství, 2021-06) Lager, Ioan E.; Stumpf, MartinThe amplitude-modulated, cosine power-exponential (PE) and windowed-power (WP) pulses are discussed, by insisting on their time-domain normalization. Illustrative examples of signatures and their correspondent frequency-domain behavior are given. These examples compellingly demonstrate the possibility to replace non-causal pulses of prevalent use by causal, or even time-windowed, pulses with closely resembling signatures.
- ItemCPW Fed Koch Modified Fractal Antenna Backed with Partial Ground for Multiband Wireless Applications(Společnost pro radioelektronické inženýrství, 2021-06) Dash, Rajib Kumar; Saha, Puspendu Bikash; Ghoshal, Dibyendu; Palai, GopinathIn this article, modified Koch fractal geometry-based patch antenna up to second iteration is implemented with partial ground configuration to achieve multiband response with wideband behavior at each of the resonating bands. The antenna is designed to operate over C and X bands that can be useful for Satellite, Radar and DBS TV applications. FR-4 epoxy substrate of maximum dimension 35×30×1.6 〖mm〗^3 (0.70λ_0×0.6λ_0×0.03λ_0 ) is used to simulate the antenna in HFSS 15 (λ_0 is the free space wavelength corresponding to the lowest resonance frequency). The design is started with a truncated star shape patch and ended up with five circular slots embedded Koch fractal through several design steps. In addition, coplanar waveguide (CPW) feeding is applied to achieve multiband response and wideband behavior over each operating band. The proposed antenna exhibits multiband response at 6.06 GHz, 9.76 GHz, 10.92 GHz, 11.68 GHz and 14.4 GHz with operating bands (5.8 – 6.31 GHz), (9.2 – 10.08 GHz), (10.78 – 12.36 GHz) and (13.64 – 15 GHz) respectively. A fabricated prototype of the proposed antenna is tested using Vector Network Analyzer (VNA). It has shown adequate amount of matching between the simulation and measured results.
- ItemCompact Wideband SIW Based Bandpass Filter for X, Ku and K Band Applications(Společnost pro radioelektronické inženýrství, 2021-06) Duraisamy, Tharani; Kamakshy, Selvajyothi; Karthikeyan, Sholampettai Subramanian; Barik, Rusan Kumar; Cheng, Qingsha S.This paper presents a miniaturized bandpass filter (BPF) with characteristics of wider passband and stopband rejection using substrate integrated waveguide (SIW) technology. Slot loading mechanisms deployed on the upper layer of SIW and defective ground structure (DGS) on the ground plane are utilized to achieve wider passband and stopband respectively. The slots on the top layer along with DGS significantly enhances the selectivity of the filter by generating three transmission zeros (TZs) on the upper side of the passband. The proposed filter is simulated using full-wave simulators and the performance is validated through fabrication and testing of the prototype. The proposed SIW filter exhibits a low insertion loss of 1.52 dB over a wider passband from 9.17 GHz to 20.31 GHz with a 3 dB fractional bandwidth (FBW) of 76%. Further, a wider upper stopband is achieved with the rejection of more than 16 dB in the frequency range of 23 GHz to 40 GHz. The filter provides a flat group delay response of approximately 0.19 ns over the wider passband. The electrical size of the fabricated prototype is 1.05λg × 0.67λg, where λg denotes the guided wavelength in the dielectric substrate at the center frequency of 16 GHz.