2020/2

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Miniaturization and Harmonic Suppression of Power Divider using Coupled Line Section for High Power Applications
(Společnost pro radioelektronické inženýrství, 2020-06) Kumar, Mukesh; Sen, Gobinda; Islam, S. K. Nurul; Parui, Susanta Kumar; Das, Santanu
This paper presents a compact transmission line based on the coupled line section to reduce the circuit size of Gysel power divider (GPD). The line composed of one direct line and one coupled line section. The coupled line section consists of two series lines and one coupled line. The proposed line not only reduces circuit size but also improve the out-off band performance. To validate the properties of the line, a GPD) is designed at 1 GHz. The physical size of the GPD occupies only 38% (0.32λg×0.16λg, λg¬ is the guided wavelength) circuit area compared to reference GPD. Furthermore, the proposed design includes 2nd order harmonic suppression with attenuation level better than -20 dB. The GPD is designed with a substrate of dielectric constant of 2.2, thickness of 0.787 mm, and loss tangent 0.0009.
A Multi-Reconfigurable CLL-Loaded Planar Monopole Antenna
(Společnost pro radioelektronické inženýrství, 2020-06) Fakharian, Mohammad M.; Rezaei, Pejman; Orouji, Ali A.
In this paper, multi-reconfiguration capabilities of a planar monopole antenna with two switchable capacitively loaded loops (CLLs), as near field resonant parasitic elements, are introduced. The idea is to apply the CLLs not only to minimize the dimensions of the antenna, but also to present multiple resonances, which can be satisfactorily chosen by applying switches placed across six gaps of the CLLs. By changing the switched states, it is feasible to obtain different reconfigurations such as frequency agility (from 1.5 to 2.9 GHz), polarization diversity (with circular polarization bandwidth from 1.59 to 1.72 GHz), and various shapes of the radiation patterns and beam directions (change in the ±30° y-direction) of the antenna. The transmutation of polarization designs from their linear counterparts to left hand and right hand circular polarizations by introducing an asymmetry in the configuration of the two-CLLs is also represented. The prototypes of the proposed antenna are fabricated and tested. The measured reflection coefficient, radiation pattern, gain and axial ratio results are presented and compared to the corresponding simulated values.
Efficient Relay Selection Algorithm for Non-Orthogonal Amplify-and-Forward Cooperative Systems over Block-Fading Channels
(Společnost pro radioelektronické inženýrství, 2020-06) Yunida, Yunida; Muharar, Rusdha; Away, Yuwaldi; Nasaruddin, Nasaruddin
In this paper, an efficient relay selection (RS) algorithm for non-orthogonal amplify-and-forward (NAF) cooperative systems over block-fading channels, also known as block-fading NAF (BFNAF) protocol, is developed. The best relay is selected from a subset of available relay nodes based on the maximum criterion of their capacity bounds in half-duplex (HD) mode, together with the power allocation, to obtain the energy efficiency (EE) for the proposed RS scheme. We derived an exact closed-form expression of the outage probability and throughput for evaluating the system performance. The energy consumption was also numerically evaluated to determine the optimized EE of the proposed RS scheme for each transmission protocol with two modulation schemes. The numerical results indicated that the proposed RS scheme with the BFNAF protocol outperforms the previous RS scheme with orthogonal AF (OAF) protocol in terms of both the outage probability and the throughput as the number of relays is increased and the average transmit power is optimally allocated for each transmission phase. Moreover, in the case of the optimized EE, it is found that by using quadrature amplitude modulation (QAM), the EE of the proposed RS scheme is 48.9% higher than that of binary phase-shift keying (BPSK) modulation.
Implementation of a New and Modified Scheme of Butler Matrix for C-Band Applications with Enhanced Characteristics
(Společnost pro radioelektronické inženýrství, 2020-06) Maleki, Mostafa; Nourinia, Javad; Ghobadi, Changiz; Naderali, Rahim
In this paper, the structure of a miniaturized broadband 4 × 4 Butler matrix is presented. All components of the proposed feeding network are designed in a way that they have the smallest electrical size and acceptable performance in the C band. Despite conventional Butler matrix consists of phase shifters, the proposed network benefits from dummy crossover, which leads to improving the phase difference bandwidth. Since in beam switching networks, 90° coupler has a vital role, the main focus is concentrated on the aforementioned component as mentioned above. The compactness of the proposed coupler is associated with embedding the S-shaped arms instead of ordinary elements. Due to overcoming the problem of a mismatch phase difference between phase shifter and crossover, the modified dummy crossover is used. In order to improve the overall performance of the depicted feeding network, S-shaped electromagnetic bandgap structures are used between elements. They reduce destructive mutual coupling effect hence leads to enhance total network efficiency. The extracted results determine that the bandwidth of the presented network is from 3.5 ~ 8.2 GHz that covers the C band totally.
Multiband Filter Design Using Generalized Mapping Functions and Synthesis with Lumped Resonators
(Společnost pro radioelektronické inženýrství, 2020-06) Yildiz, Serkan; Aksen, Ahmet; Kilinc, Sedat; Yaman, Siddik B.
In this paper, a new multiband frequency mapping function is proposed to design multiband filter. The presented mapping function is a generalized form of the sequential low pass to band pass (LPtoBP) transformation. The multiband filter design is based on the application of the frequency mapping function on a LP prototype. The synthesis of the resulting multiband filter is obtained by lumped element resonators. Several examples are presented to validate the proposed design approach. A triple band filter implementation and measurement results are presented.

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