Recent Submissions

Now showing 1 - 5 of 23
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    CipherCAD Testbed
    (Společnost pro radioelektronické inženýrství, 2021-06) Platenka, Vaclav; Mazalek, Antonin
    The CipherCAD testbed is a unique workplace for the development, design, testing, verification and teaching of the communications systems. CipherCAD is at the core of the workplace, which is an application primarily designed for solving cryptographic tasks. The application can also be used for communicating with hardware communications devices. The workplace is used in the Department of Communications Technologies at the University of Defense. The article will present selected exam-ples used in this workplace. The introduction introduces CipherCAD and the possibilities for creating simple models. The first model to be selected shows how to control SDR IZ225 and process the signals received. The next model shows how selected modulated signals are gener-ated in real time, and their transmission throughout the whole chain of communications. The models that follow show how they can be used in the field of communications protocols, VoIP transfer and changing any of the parameters of the transmitted information.
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    Harmonic Suppression by Using T-shaped Spur-Line in a Compact Hairpin-Line Bandpass Filter
    (Společnost pro radioelektronické inženýrství, 2021-06) Das, Tarun Kumar; Chatterjee, Sayan
    This article exhibits the design of a fourth-order compact hairpin-line filter centered at 2.5 GHz and 3 dB fractional bandwidth of 5% along with a sharp roll-off factor and wide stopband characteristics required for Wireless Local Area Network (WLAN). Miniaturization of the conventional hairpin-line filter has been achieved by folding the open end arms twice towards the inward direction and accordingly, a size reduction of 42% has been obtained. Subsequently, T-shaped spur-lines with optimum dimensions have been incorporated at both the inner and outer edges of the coupled arms of the folded hairpin-line cell. Accordingly, two fourth-order folded filters with outer T-shaped and double T-shaped spur-lines have been designed and verified experimentally. An extended stopband with a rejection level of 39 dB up to 3.2f_0 along with a size reduction of 46% has been achieved.
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    A Wideband Conductor Backed Coplanar Waveguide Fed Implantable Antenna Operable in Different Tissues for Biotelemetry Applications
    (Společnost pro radioelektronické inženýrství, 2021-06) Okan, Tayfun
    A wideband biocompatible implanted antenna is designed for wireless biotelemetry applications at industrial, scientific and medical (ISM) band (2.4-2.48 GHz). The antenna is fed by a conductor backed coplanar waveguide (CB-CPW) structure and two H-shaped slots are etched side by side on the patch of the antenna to create a resonance at the desired frequency. The experimental and simulation measurements are performed by using skin, fat and muscle tissue layers. The impedance bandwidth (S_11≤-10 dB) of the proposed antenna is measured as 0.406 GHz (2.272 - 2.678 GHz), when the fabricated antenna is implanted inside a three-layered human body mimicking gel. By using the advantage of having a wide bandwidth, the designed antenna is analyzed inside different tissue types and tissue thicknesses. For every obtained simulation and experimental result, it is observed that the antenna always covers the ISM band, which is the most significant contribution of this study. The size of the implantable antenna is 16×13×1.93 mm3, where both sides of the antenna is covered by a superstrate material to extend the life of the antenna inside the tissue.
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    Compact 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.
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    Study 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-Jun
    The 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).