This letter presents a multilayer approach for suppressing the higher order modes of substrate integrated waveguide (SIW) bandpass filters. Rectangular SIW resonators in multilayer substrates can be ...vertically coupled with magnetic and/or electric coupling by the proposed apertures etched on the middle metal layer. Harmonic passbands produced by the first higher-order mode TE 102 can be suppressed thanks to the proposed weak coupling or mixed coupling schemes in connection with the TE 102 mode. Compared with conventional horizontally coupled filter, the proposed filters also show a compact physical size. To demonstrate the proposed design method, two double-layered SIW bandpass filters Filter (I and II) are fabricated and measured. The experimental results show that the maximum rejection levels at the TE 102 mode frequencies are below -30 dB and -20 dB for Filter I and II, respectively. Furthermore, simulated and measured results also show a good agreement.
In this paper, a dual-band dual-sense circularly polarized (CP) magnetoelectric dipole antenna is proposed. The antenna consists of a cavity reflector, two pairs of vertical and horizontal copper ...plates, and a crossed Γ-shaped feeding structure. The shorted vertical plates work as quasi-magnetic dipoles (M-dipoles), while the connected horizontal plates work as electric dipoles (E-dipoles). Two M-dipoles and E-dipoles are designed to possess different heights and lengths, and thus they are able to achieve separate operation bands. To generate dualsense CP performance, the M-dipoles and E-dipoles are placed in parallel and the adjacent E-dipoles extend along the opposite directions. Benefiting from the intrinsic 90° phase difference between the M-dipole and E-dipole, the left-hand CP is achieved within the lower operation band (2.15-3.4 GHz) and the righthand CP is achieved within the upper band (4-6.3 GHz). The proposed antenna possesses a unidirectional radiation pattern with high front-to-back ratio (≥22 dB). Furthermore, high gain (≥8 dBi) and radiation efficiency (≥90%) are also achieved.
Quasi-cyclic low-density parity-check (QC-LDPC) codes, which have been adopted by the Consultative Committee for Space Data Systems (CCSDS), are widely used in Deep-Space (AR4JA) and Near-Earth (C2) ...communications. A large number of encoder architectures with CCSDS recommended standard have been proposed. But the existing architectures are not efficient enough in high-throughput implementations, many architectures have a lot of logical resources and registers. In this brief, we introduce a novel architecture with low resource utilization. A grouping algorithm is used to extract the common subexpressions (CS) of the encoding algorithm. Similar circuit structures are integrated through a two-layer architecture, which further reduces logical resources. For the special size of the generator's matrix, we introduce a preprocessing method. In addition, configuration registers are used to replace the control unit. Implemented and verified on FPGA, the proposed architecture achieves a throughput of 4.69 Gbps using only 1658 LUTs and 1038 FFs. Compared with the previous architectures, this architecture achieves lower resource utilization and multi-Gbps throughput.
Radio Frequency Identification (RFID) is a widely used wireless communication technology. In terms of mobile RFID tags, the relative position between the tags and the reader changes, and consumers ...can obtain product-related information in tags by using readers. Anti-collision is an important scheme for readers to identify RFID tags. Tag estimation is at the core of the efficient anti-collision process, especially when tags move. In this paper, we propose a Mobile tags Identification Procedure model (MTIP), and establish a feasible mobile tags estimation model based on MTIP. In the mobile tags estimation model, we use superposition principle of Poisson process to solve the tag estimation problem. Based on these models, a new anti-collision algorithm specifically for the mobile RFID tags is proposed. Performance evaluation shows that the proposed algorithm significantly outperforms classical Q algorithm of the Electronic Product Code Class-1 Generation-2 system (EPC-C1G2) and the recent Symbolic Single Resolution Blocking (SSRB) algorithm in terms of success-rate and achieves similar efficiency for static RFID system.
In this paper, two- and three-pole microstrip LC constant fractional bandwidth (CFBW) and constant absolute bandwidth (CABW) tunable bandpass filters are proposed. The equivalent-circuit models are ...presented to study the tunable mechanism. The filter can be reconfigured by changing the capacitance of the LC resonators. Based on electric coupling coefficient compensation, second- and third-order tunable equivalent-circuit models with CFBW/CABW are presented. For demonstration, a semiconductor varactor diode loaded microstrip LC resonator is adopted in our work to design the second- and third-order tunable filters. The S -parameters, group delays, and third-order intercept points for different center frequencies of the filters are presented. Each resonator requires only one varactor diode for both central frequency and resonator coupling coefficient control.
Third‐order intermodulation (IM3) is considered as a typical metric to evaluate passive intermodulation (PIM) in electrical connectors, which may be affected by the second‐order effect in the circuit ...with cascaded non‐linearities. In this study, the effects of second harmonics and second‐order intermodulation on the IM3 powers were theoretically modelled and experimentally verified. Combined with mathematical modelling, an equivalent circuit model of a passive non‐linear source was presented to investigate the effect of second‐order signals on the IM3 powers. A modified non‐linear transfer function was developed by considering multiple non‐linear superpositions in cascaded non‐linearities. Based on the designed two‐tone test, a mathematical expression was provided with the determination of correlation model coefficients. Numerical simulations were performed by using the proposed model, demonstrating the effect of signals induced by the second‐order non‐linearity on the IM3 powers in series passive components. The IM3 powers resulting from cascaded connectors associated with different signal frequencies were predicted. Coaxial connector samples were designed as cascaded PIM sources in circuits, which were experimentally measured in a GSM 900 MHz frequency band. Good agreement was obtained between the predictions and measurements with error of 0.76 dB in average.
This article introduces a novel Ultra Wide Band (UWB) Multiple Input Multiple Output (MIMO) antenna with Triple-band notched characteristics. The overall dimensions of the antenna are 18 × 34 mm2. ...The designed antenna has two similar flower-shaped radiators with L-shape strips, common ground with two flag-shaped decoupling stubs and T-shape strips for notched band characteristics. Two flag-shaped stubs are used to achieve 22 dB improved isolation. The S11 of the designed antenna is less than −10 dB between 3.07 GHz and 12.40 GHz, having various stopped bands of WiMAX, WLAN and X bands. The presented antenna is examined and investigated in terms of S-parameters, Mutual Coupling, Gain, Envelope Correlation Coefficient (ECC), Efficiency and Diversity Gain (DG).
A stable and efficient anti-collision protocol is very important for tags identification in many radio frequency identification (RFID) system such as flow productions and automatic controls. In this ...paper, we introduce an efficient anti-collision protocol named collision tree protocol (CT) and analyze the stability of it in detail. Both theoretical results and experimental results indicate that the performance of CT is only dependent on the number of tags to be identified and not influenced by the distribution of tag IDs and other factors, and the average performance of CT for one-tag identification converges to a constant. According to the definition of the stability of an anti-collision protocol, CT is a stable anti-collision protocol for RFID tag identification. The stability proposed in this paper provides a new performance metric for evaluating the performance of different anti-collision protocols for RFID tag identification. As a stable protocol, the time delay and the power consumption for one-tag identification of CT tend to be constant. Therefore, CT can be applied to various tags identification systems and especially suited to the RFID systems in which both the time delay and the power consumption for tags (or objects) identification are required to be limited and stable.
Synthesis of unequally spaced linear antenna arrays is considered in this paper. A recently developed new differential evolution algorithm is applied to solve the problem. Both position-only and ...position-phase synthesis have been studied. Effect of angle resolution has also been investigated. Synthesis results show that our algorithm is able to obtain better synthesis result reliably and efficiently.
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