2023/1

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Design and Fabrication of Birdcage Resonators for Low-pressure Plasma Excitation
(Společnost pro radioelektronické inženýrství, 2023-04) Jurik, K.; Stary, J.; Drexler, P.
This paper presents a design, analysis and optimization of birdcage resonators employed in a novel radiofrequency plasma source. Three resonators were simulated and fabricated. The resonators differ in their design and in the different materials of used dielectric – polyimide and polytetrafluorethylene (PTFE). The resonance frequency of fabricated samples possesses a maximal error of 2.2 % compared to the simulated values. The performance in plasma excitation is related to the electrical parameters, while the best performing resonator (PTFE-based) exhibits the maximum real impedance of 644.3 Ω at the resonance frequency and the 799.5 V/m electric field strength. This resonator shows the best power efficiency in a plasma ignition experiment. The resonator ignited the discharge at ca. 1 Pa of ambient air atmosphere with only 0.34 W of input radiofrequency power.
Moving Target Simulation of Multi-Band Radar Based on Doppler Frequency Signal Generation Technology
(Společnost pro radioelektronické inženýrství, 2023-04) Hao, J.; Wang, X.; Sun, X.; Gao, H.; Zou, L.
This paper proposes a corner reflector and Luneburg ball reflector group. The omnidirectional radar cross-sectional (RCS) distribution characteristics of a fighter are simulated using the sharp and smooth RCS distribution features of the corner and the Luneburg ball reflectors, respectively. A new type of Doppler signal generation principle is proposed to design a Doppler frequency simulator to transmit frequency signals by connecting in parallel with the metal layer of the corner reflector and the Luneburg sphere ball, and then transmit through their other end. The existing radar target aircraft cannot simulate the RCS and speed of the targets that are less than 0.005 m2 by enhancing the echo intensity of the target location, which makes it impossible for the military to conduct practice drills and evaluate the effectiveness of the air defense systems. The experimental results show that the Doppler frequency simulator successfully simulates the target speed of 0-80 km/h and when the speed is greater than 20 km/h, the error of the simulation frequency is less than 1.5%. The proposed method can provide guidance and a theoretical basis for simulating the speed of various types of aircraft in future work.
A Compact Band-Notched UWB MIMO Antenna with Enhanced Isolation Using Comb Shaped Decoupling Element
(Společnost pro radioelektronické inženýrství, 2023-04) Chatterjee, S.; Rana, S.; Sanyal, R.
A compact 37mm × 26 mm two element multiple-input-multiple-output (MIMO) antenna is presented for ultra wide band (UWB) system application with band notched characteristics. The proposed antenna comprises two semi trapezoidal shaped monopole radiating elements. The band rejection feature around 3.5 GHz has been achieved by incorporating the open ended quarter wavelength spiral shaped slot resonator on the patched surface. In order to realize the enhanced isolation, comb shaped symmetrical stub arrangement are embedded at the U shaped etched periphery to the stepped ground plane between the monopole radiators. This novel design approach leads towards isolation enhancement better than 20 dB throughout the UWB spectral range (3.1 -10.6 GHz) with peak isolation near about 46 dB. The Envelope Correlation Coefficient is significantly lower than 0.005 in entire operating range except the WiMAX rejection band.
An Overview of Fully On-Chip Inductors
(Společnost pro radioelektronické inženýrství, 2023-04) Ondica, R.; Kovac, M.; Hudec, A.; Ravasz, R.; Maljar, D.; Stopjakova, V.; Arbet, D.
This paper focuses on full integration of passive devices, especially inductors with emphasis on multi-layer stacked (MLS) structures of fully integrated inductors using patterned ground shield (PGS) and fully integrated capacitor. Comparison of diﬀerent structures is focused on the main electrical parameters of integrated inductors (e.g. inductance L, inductance density LA, quality factor Q, frequency of maximum quality factor F Qmax, self-resonant frequency FSR, and series resistance R DC ) and other non-electrical parameters (e.g. required area, manufacturing process, purpose, etc.) that are equally important during comparison of the structures. Categorization of inductor structures with most signiﬁcant results that was reported in the last years is proposed according to manufacturing process. Final geometrical and electrical properties of the structure in great manner accounts to the fabrication process of integrated passive device. This work oﬀers an overview and state-of-the-art of the integrated inductors as well as manufacturing processes used for their fabrication. Second purpose of this paper is insertion of the proposed structure from our previous work among the other results reported in the last 7 years. With the proposed solution, one can obtain the highest inductance density L A = 23.59 nH/mm 2 and second highest quality factor Q = 10.09 amongst similar solutions reported in standard technologies that is also suitable competition for integrated inductors manufactured in advanced technology nodes.
Two-Dimensional Frequency Domain Second-Order Keystone Transform for Weak Target Integration Detection Based on Bistatic Radar Configuration
(Společnost pro radioelektronické inženýrství, 2023-04) Lei, Z.; Rao, X.; Jin, P.; Yi, H.; Hu, J.
In this paper, a novel coherent integration algorithm, i.e., two-dimensional frequency domain second-order keystone transform (FDSOKT), is proposed to detect a weak maneuvering target based on bistatic radar configuration. To eliminate range migration and Doppler frequency migration, the radar echoes are transformed into two-dimensional frequency domain firstly, and then a series of rescaling transforms, matched filter functions and compensation functions are performed respectively. With the elimination of the couplings between range frequency and azimuth frequency caused by radial velocity and acceleration, the energy of the echoes is focused in two-dimensional time domain, which improves the detection performance of weak target. In addition, to deal with Doppler ambiguity, different Doppler ambiguity cases are discussed and could be solved well. At last, some simulation experiments are provided and the effectiveness of FDSOKT is proved by the results.

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